Westlake Chemical Partners 424B5 Prospectus supplement for primary offering

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-216617

PROSPECTUS SUPPLEMENT

(To Prospectus dated March 24, 2017)

LOGO

Common Units

Representing Limited Partner Interests

Having an Aggregate Offering Amount of Up to $50,000,000

This prospectus supplement and the accompanying base prospectus relate to the issuance and sale from time to time of common units representing limited partner interests in Westlake Chemical Partners LP having an aggregate offering amount of up to $50,000,000 through one or more of our managers. These sales, if any, will be made pursuant to the terms of an equity distribution agreement between us and UBS Securities LLC, Barclays Capital Inc., Citigroup Global Markets Inc., Deutsche Bank Securities Inc., Merrill Lynch, Pierce, Fenner & Smith Incorporated, RBC Capital Markets, LLC and Wells Fargo Securities, LLC (collectively, the “managers” and each, a “manager”), which we previously filed as an exhibit to a Current Report on Form8-K with the Securities and Exchange Commission (the “SEC”), and will be made by means of ordinary brokers’ transactions through the facilities of the New York Stock Exchange (the “NYSE”), any other national securities exchange or facility thereof, a trading facility of a national securities association or an alternate trading system, at market prices prevailing at the time of sale or negotiated prices, to or through a market maker or directly on or through an electronic communication network, in block transactions or as otherwise agreed with the managers.

Under the terms of the equity distribution agreement, we may also sell common units to any manager as principal for its own account at a price agreed upon at the time of the sale. If we sell common units to any manager as principal, we will enter into a separate terms agreement with that manager and we will describe that agreement in a separate prospectus supplement or pricing supplement.

Our common units trade on the NYSE under the symbol “WLKP.” On October 3, 2018, the last reported trading price of our common units on the NYSE was $24.68 per common unit.

The compensation for each manager for sales of our common units sold through it shall be at a commission rate of up to 2.0% of the gross sales price. We will use the net proceeds from any sales under this prospectus supplement as described herein under “Use of Proceeds.”

Investing in our common units involves certain risks. See “Risk Factors” on pageS-3 of this prospectus supplement and on page 2 of the accompanying base prospectus.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement. Any representation to the contrary is a criminal offense.


UBS Investment Bank		Barclays		BofA Merrill Lynch


Citigroup		Deutsche Bank Securities

RBC Capital Markets		Wells Fargo Securities

The date of this prospectus supplement is October 4, 2018.

We have not, and the managers have not, authorized anyone to provide any information or to make any representations other than those contained or incorporated by reference in this prospectus supplement or in the accompanying base prospectus. Neither we nor the managers take responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. In making your investment decision, you should rely only on the information contained in this prospectus, any prospectus supplement and the documents we have incorporated by reference in this prospectus. You should not assume that the information contained in this prospectus supplement or in the accompanying base prospectus is accurate as of any date other than the date shown in such documents or that the information contained in any document incorporated by reference is accurate as of any date other than the date of such document. Our business, financial condition, results of operations and prospects may have changed since those dates. We are not, and the managers are not, making an offer to sell the securities described herein in any jurisdiction where the offer or sale is not permitted. We will disclose any material changes in our affairs in an amendment to this prospectus, a prospectus supplement or a future filing with the SEC incorporated by reference in this prospectus.

TABLE OF CONTENTS

Prospectus Supplement


	Page
About This Prospectus Supplement		S-ii
Summary		S-1
Risk Factors		S-3
Use of Proceeds		S-4
Material U.S. Federal Income Tax Consequences		S-5
Plan of Distribution		S-23
Legal Matters		S-27
Experts		S-27
Forward-Looking Statements		S-27
Where You Can Find More Information		S-29


Base Prospectus
	Page
About This Prospectus		ii
Where You Can Find More Information		iii
Cautionary Statement Regarding Forward- Looking Statements		iv
Who We Are		1
Risk Factors		2
Ratio of Earnings to Combined Fixed Charges		3
Use of Proceeds		4
Description of Common Units and Preferred Units		5
Description of Partnership Securities		6
Description of Debt Securities		7
Material U.S. Federal Income Tax Consequences		15
Material U.S. Tax Consequences of Ownership of Debt Securities		30
Certain ERISA Considerations		31
Plan of Distribution		34
Legal Matters		36
Experts		36

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About This Prospectus Supplement

This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering of common units and also adds to and updates information contained in the accompanying base prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying base prospectus. The second part is the accompanying base prospectus, which provides more general information about the securities we may offer from time to time, some of which may not apply to this offering of common units. Generally, when we use the term “prospectus,” we are referring to both parts combined. If the information about the common unit offering varies between this prospectus supplement and the accompanying base prospectus, you should rely on the information in this prospectus supplement.

In making an investment decision, prospective investors must rely on their own examination of us and the terms of the offering, including the merits and risks involved. None of Westlake Chemical Partners LP, the managers or any of their respective representatives is making any representation to you regarding the legality of an investment in our common units by you under applicable laws. You should consult with your own advisors as to legal, tax, business, financial and related aspects of an investment in our common units.

Any statement made in this prospectus or in a document incorporated or deemed to be incorporated by reference into this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or in any other subsequently filed document that is also incorporated by reference into this prospectus modifies or supersedes that statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus. Please read “Where You Can Find More Information” in this prospectus supplement.

The information in this prospectus supplement is not complete. You should review carefully all of the detailed information appearing in this prospectus supplement, the accompanying base prospectus and the documents we have incorporated by reference before making any investment decision.

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Summary

This summary highlights information contained in or incorporated by reference into this prospectus supplement and the accompanying base prospectus. It does not contain all of the information that you should consider before making an investment decision. You should carefully read the entire prospectus supplement, the accompanying base prospectus and the documents incorporated by reference herein to fully understand the terms of this offering and our common units, as well as the tax and other considerations that are important in making your investment decision. Please read “Risk Factors” on pageS-3 of this prospectus supplement and on page 2 of the accompanying base prospectus, including the documents incorporated by reference herein and therein, for more information regarding risks you should consider before investing in our common units.

Unless the context otherwise requires, references in this prospectus supplement to the “Partnership,” “we,” “our,” “us” or like terms refer to “Westlake Chemical Partners LP” and, unless otherwise specified, Westlake Chemical OpCo LP and Westlake Chemical OpCo GP LLC. References in this prospectus supplement to our “general partner” refer to Westlake Chemical Partners GP LLC. References to “OpCo” refer to Westlake Chemical OpCo LP. References to “Westlake” refer collectively to Westlake Chemical Corporation and its subsidiaries, other than us, our general partner, OpCo and Westlake Chemical OpCo GP LLC, OpCo’s general partner.

WESTLAKE CHEMICAL PARTNERS LP

We are a Delaware limited partnership formed by Westlake to operate, acquire and develop ethylene production facilities and related assets. Our sole revenue generating asset is our 18.3% limited partner interest in OpCo, a limited partnership formed by Westlake and us in anticipation of our initial public offering in August 2014 to own and operate an ethylene production business. We control OpCo through our ownership of its general partner. Westlake retains the remaining 81.7% limited partner interest in OpCo as well as a significant interest in us through its ownership of our general partner, 43.8% of our limited partner units (consisting of 14,122,230 common units) and our incentive distribution rights. OpCo’s assets include (1) two ethylene production facilities at Westlake’s Lake Charles, Louisiana site, (2) one ethylene production facility at Westlake’s Calvert City, Kentucky site (“Calvert City Olefins”), and (3) a200-mile common carrier ethylene pipeline that runs from Mont Belvieu, Texas to Westlake’s Longview, Texas facility.

PRINCIPAL EXECUTIVE OFFICES AND INTERNET ADDRESS

Our principal executive offices are located at 2801 Post Oak Boulevard, Suite 600, Houston, Texas 77056, and our telephone number is (713)585-2900. Our website ishttp://www.wlkpartners.com. Information on our website or any other website is not incorporated by reference into this prospectus and does not constitute a part of this prospectus.

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THE OFFERING

Common units offered by us

Common units having an aggregate offering amount of up to $50,000,000.

Use of proceeds

We intend to use the net proceeds of sales of common units offered hereby, after deducting managers’ commissions and our offering expenses, for general partnership purposes, including the funding of potential drop-downs and other acquisitions. Please read “Use of Proceeds” in this prospectus supplement.

Material U.S. federal income tax consequences

For a discussion of certain material U.S. federal income tax consequences that may be relevant to prospective unitholders who are individual citizens or residents of the United States, please read “Material U.S. Federal Income Tax Consequences” in this prospectus supplement, which amends and supersedes the discussion under “Material U.S. Federal Income Tax Consequences” in the accompanying base prospectus in its entirety.

Exchange listing

Our common units trade on the NYSE under the symbol “WLKP.”

Risk factors

You should read “Risk Factors” on pageS-3 of this prospectus supplement and on page 2 of the accompanying base prospectus and the risk factors described in the documents incorporated herein by reference and the other cautionary statements contained in this prospectus supplement, to ensure you understand the risks associated with an investment in our common units.

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Risk Factors

An investment in our common units involves risk. You should carefully read the risk factor set forth below, the risk factors included under the caption “Risk Factors” on page 2 of the accompanying base prospectus and the risk factors included in Item 1A. “Risk Factors” in our Annual Report on Form10-K for the fiscal year ended December 31, 2017 and, to the extent applicable, our Quarterly Reports onForm 10-Q and Current Reports onForm 8-K, together with all of the other information included or incorporated by reference in this prospectus. If any of these risks were to occur, our business, financial condition, results of operations or prospects could be materially adversely affected. In such case, the trading price of our common units could decline, and you could lose all or part of your investment.

RISKS RELATED TO OUR COMMON UNITS

The market price of our common units may be adversely affected by the future issuance and sale of additional common units, including pursuant to the equity distribution agreement, or by our announcement that such issuances and sales may occur.

We cannot predict the size of future issuances or sales of our common units, including those made pursuant to the equity distribution agreement or in connection with future acquisitions or capital raising activities, or the effect, if any, that such issuances or sales may have on the market price of our common units. In addition, the managers will not engage in any transactions that stabilize the price of our common units. The issuance and sale of substantial amounts of common units, including issuances and sales pursuant to the equity distribution agreement, or announcement that such issuances and sales may occur, could adversely affect the market price of our common units.

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Use of Proceeds

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Material U.S. Federal Income Tax Consequences

The tax consequences to you of an investment in our common units will depend in part on your own tax circumstances. This discussion amends and supersedes the discussion under “Material U.S. Federal Income Tax Consequences” in the accompanying base prospectus in its entirety. Please also read Part I, Item 1A. “Risk Factors—Tax Risks to Common Unitholders” in our Annual Report on Form10-K for the year ended December 31, 2017 for a discussion of the tax risks related to purchasing and owning our common units. You are urged to consult with your own tax advisor about the federal, state, local and foreign tax consequences peculiar to your circumstances.

This section summarizes the material U.S. federal income tax consequences that may be relevant to prospective unitholders and is based upon current provisions of the U.S. Internal Revenue Code of 1986, as amended (the “Code”), existing and proposed U.S. Treasury regulations thereunder (the “Treasury Regulations”), and current administrative rulings and court decisions, all of which are subject to change. Changes in these authorities may cause the federal income tax consequences to a prospective unitholder to vary substantially from those described below, possibly on a retroactive basis. Unless the context otherwise requires, references in this section to “we,” “us” or “the Partnership” are references to Westlake Chemical Partners LP and its subsidiaries.

Legal conclusions contained in this section, unless otherwise noted, are the opinion of Vinson & Elkins L.L.P. and are based on the accuracy of representations made by us to them for this purpose. However, this section does not address all federal income tax matters that may affect us or our unitholders, such as the application of the alternative minimum tax. This section also does not address local taxes, state taxes,non-U.S. taxes, or other taxes that may be applicable, except to the limited extent that such tax considerations are addressed below under “—State, Local and Other Tax Considerations.” Furthermore, this section focuses on unitholders who are individual citizens or residents of the United States (for federal income tax purposes), who have the U.S. dollar as their functional currency, who use the calendar year as their taxable year, who purchase common units in this offering, who do not materially participate in the conduct of our business activities and who hold such common units as capital assets (typically, property that is held for investment). This section has limited applicability to corporations (including other entities treated as corporations for federal income tax purposes), partnerships (including other entities treated as partnerships for federal income tax purposes), estates, trusts,non-resident aliens or other unitholders subject to specialized tax treatment, such astax-exempt entities,non-U.S. persons, individual retirement accounts (“IRAs”), employee benefit plans, real estate investment trusts or mutual funds.

Accordingly, we encourage each prospective unitholder to consult the unitholder’s own tax advisor in analyzing the federal, state, local andnon-U.S. tax consequences that are particular to that unitholder resulting from ownership or disposition of our common units and potential changes in applicable tax laws.

We have requested and obtained a favorable private letter ruling from the Internal Revenue Service (the “IRS”) to the effect that the production, transportation, storage and marketing of ethylene and itsco-products will constitute “qualifying income” within the meaning of Section 7704 of the Code. However, no ruling has been or will be requested from the IRS regarding our classification as a partnership for U.S. federal income tax purposes. Instead, we are relying on the opinions and advice of Vinson & Elkins L.L.P. with respect to the matters described herein. An opinion of counsel represents only that counsel’s best legal judgment and does not bind the IRS or a court. Accordingly, the opinions and statements made herein may not be sustained by a court if contested by the IRS. Any such contest of

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Material U.S. Federal Income Tax Consequences

the matters described herein may materially and adversely impact the market for our common units and the prices at which our common units trade. In addition, our costs of any contest with the IRS will be borne indirectly by our unitholders and our general partner because the costs will reduce our cash available for distribution. Furthermore, the tax consequences of an investment in us may be significantly modified by future legislative or administrative changes or court decisions, which may be retroactively applied.

For the reasons described below, Vinson & Elkins L.L.P. has not rendered an opinion with respect to the following federal income tax issues:

the treatment of a unitholder whose common units are the subject of a securities loan (e.g., a loan to a short seller to cover a short sale of common units) (please read “—Tax Consequences of Unit Ownership—Treatment of Securities Loans”);

whether our monthly convention for allocating taxable income and losses is permitted by existing Treasury Regulations (please read “—Disposition of Common Units—Allocations Between Transferors and Transferees”);

whether our method for taking into account Section 743 adjustments is sustainable in certain cases (please read “—Tax Consequences of Unit Ownership—Section 754 Election” and “—Uniformity of Common Units”) and

whether our use of simplifying conventions for making adjustments to “book” basis and relevant allocations is permitted by existing Treasury Regulations (please read “—Tax Consequences of Unit Ownership—Allocation of Income, Gain, Loss and Deduction” and “—Uniformity of Units”).

TAXATION OF THE PARTNERSHIP

Partnership status

We are treated as a partnership for U.S. federal income tax purposes and, therefore, subject to the discussion below under “—Administrative Matters—Information Returns and Audit Procedures,” generally will not be liable for entity-level federal income taxes. Instead, as described below, each of our unitholders will take into account its respective share of our items of income, gain, loss and deduction in computing its federal income tax liability as if the unitholder had earned such income directly, even if we make no cash distributions to the unitholder. Distributions we make to a unitholder will not give rise to income or gain taxable to such unitholder, unless the amount of cash distributed exceeds the unitholder’s adjusted tax basis in its common units. Please read “—Tax Consequences of Unit Ownership—Treatment of Distributions” and “—Disposition of Common Units”).

Section 7704 of the Code generally provides that publicly-traded partnerships will be treated as corporations for federal income tax purposes. However, if 90% or more of a partnership’s gross income for every taxable year it is publicly-traded consists of “qualifying income,” the partnership may continue to be treated as a partnership for federal income tax purposes (the “Qualifying Income Exception”). Qualifying income includes (i) interest, (ii) dividends, (iii) real property rents within the meaning of Section 856(d) of the Code, as modified by Section 7704(d)(3) of the Code, (iv) gains from the sale or other disposition of real property, (v) income and gains derived from the exploration, development, mining or production, processing, refining, transportation (including pipelines transporting gas, oil, or products thereof) or the marketing of any “mineral or natural resource,” and (vi) gains from the sale or other disposition of capital assets (or property described in Section 1231(b) of the Code) held for the production of income that otherwise constitutes qualifying income. We estimate that less than 3.0% of

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Material U.S. Federal Income Tax Consequences

our current gross income is not qualifying income; however, this estimate could change from time to time.

We have requested and obtained a favorable private letter ruling from the IRS, which has been confirmed by Treasury Regulations, to the effect that the production, transportation, storage and marketing of ethylene and itsco-products will constitute “qualifying income” within the meaning of Section 7704 of the Code. However, no ruling has been or will be requested from the IRS regarding our classification as a partnership for U.S. federal income tax purposes. Instead we have relied on the opinion of Vinson & Elkins L.L.P. that, based upon the Code, existing Treasury Regulations, published revenue rulings and court decisions and representations described below, Westlake Chemical Partners LP and each of our partnership and limited liability company operating subsidiaries will be classified as a partnership or will be disregarded as an entity separate from us for federal income tax purposes.

Vinson & Elkins L.L.P. is of the opinion that we will be treated as a partnership for federal income tax purposes and each of our partnership and limited liability company operating subsidiaries will be treated as a partnership or will be disregarded as an entity separate from us. In rendering its opinion, Vinson & Elkins L.L.P. has relied on factual representations made by us and our general partner, including, without limitation:

(a) Neither we nor any of our partnership or limited liability company operating subsidiaries has elected or will elect to be treated as a corporation for federal income tax purposes; and

(b) For each taxable year since and including the year of our initial public offering, more than 90% of our gross income has been and will be income of a character that Vinson & Elkins L.L.P. has opined is “qualifying income” within the meaning of Section 7704(d) of the Code, including income earned pursuant to processes described in our private letter ruling.

We believe that these representations are true and will be true in the future.

If we fail to meet the Qualifying Income Exception, other than a failure that is determined by the IRS to be inadvertent and that is cured within a reasonable time after discovery (in which case the IRS may also require us to make adjustments with respect to our unitholders or pay other amounts), we will be treated as transferring all of our assets, subject to all of our liabilities, to a newly formed corporation, on the first day of the year in which we fail to meet the Qualifying Income Exception in return for stock in that corporation and then as distributing that stock to our unitholders in liquidation of their interests in us. This deemed contribution and liquidation should not result in the recognition of taxable income by our unitholders or us so long as the aggregate amount of our liabilities does not exceed the adjusted tax basis of our assets. Thereafter, we would be treated as an association taxable as a corporation for federal income tax purposes.

The present U.S. federal income tax treatment of publicly traded partnerships, including us, or an investment in our common units may be modified by administrative or legislative action or judicial interpretation at any time. From time to time, members of the U.S. Congress have proposed and considered substantive changes to the existing federal income tax laws that would affect publicly-traded partnerships. One such legislative proposal would have eliminated the Qualifying Income Exception upon which we rely for our treatment as a partnership for federal income tax purposes.

Notwithstanding that Treasury Regulations and our private letter ruling treat our income from the production, transportation, storage and marketing of ethylene and itsco-products as “qualifying income,” there can be no assurance that there will not be further changes to the Treasury Department’s interpretation of the qualifying income rules in a manner that could impact our ability to qualify as a partnership in the future.

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Material U.S. Federal Income Tax Consequences

It is possible that a change in law could affect us and may be applied retroactively. Any such changes could negatively impact the value of an investment in our common units. If for any reason we are taxable as a corporation in any taxable year, our items of income, gain, loss and deduction would be taken into account by us in determining the amount of our liability for federal income tax, rather than being passed through to our unitholders. Our partnership agreement provides that if a law is enacted or existing law is modified or interpreted in a manner that subjects us to taxation as a corporation or otherwise subjects us to entity-level taxation for federal, state or local income tax purposes, the minimum quarterly distribution amount and the target distribution amounts may be adjusted to reflect the impact of that law on us.

At the state level, several states have been evaluating ways to subject partnerships to entity-level taxation through the imposition of state income, franchise, or other forms of taxation. Imposition of a similar tax on us in the jurisdictions in which we operate or in other jurisdictions to which we may expand could substantially reduce our cash available for distribution to our unitholders.

Our taxation as a corporation would materially reduce the cash available for distribution to unitholders and thus would likely substantially reduce the value of our common units. Any distribution made to a unitholder at a time when we are treated as a corporation would be (i) a taxable dividend to the extent of our current or accumulated earnings and profits, then (ii) a nontaxable return of capital to the extent of the unitholder’s adjusted tax basis in its common units (determined separately for each unit), and thereafter (iii) taxable capital gain.

The remainder of this discussion is based on the opinion of Vinson & Elkins L.L.P. that we will be treated as a partnership for federal income tax purposes.

TAX CONSEQUENCES OF UNIT OWNERSHIP

Limited partner status

Unitholders of the Partnership who are admitted as limited partners of the Partnership will be treated as partners of the Partnership for federal income tax purposes. In addition, unitholders whose common units are held in street name or by a nominee and who have the right to direct the nominee in the exercise of all substantive rights attendant to the ownership of their common units will be treated as partners of the Partnership for federal income tax purposes.

For a discussion related to the risks of losing partner status as a result of securities loans, please read “—Treatment of Securities Loans.” Unitholders who are not treated as partners of the Partnership as described above are urged to consult their own tax advisors with respect to the tax consequences applicable to them under their particular circumstances.

Flow-through of taxable income

Subject to the discussion below under “—Entity-Level Collections of Unitholder Taxes” and “—Administrative Matters—Information Returns and Audit Procedures,” and, with respect to payments we may be required to make on behalf of our unitholders, we will not pay any federal income tax. Rather, each unitholder will be required to report on its federal income tax return each year its share of our income, gains, losses and deductions for our taxable year or years ending with or within its taxable year. Consequently, we may allocate income to a unitholder even if that unitholder has not received a cash distribution.

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Material U.S. Federal Income Tax Consequences

Basis of common units

A unitholder’s tax basis in its common units initially will be the amount paid or treated as paid for those common units increased by the unitholder’s initial allocable share of our liabilities. That basis generally will be (i) increased by the unitholder’s share of our income and any increases in such unitholder’s share of our liabilities, and (ii) decreased, but not below zero, by the amount of all distributions to the unitholder, the unitholder’s share of our losses, any decreases in its share of our liabilities, and the amount of any excess business interest allocated to the unitholder. The IRS has ruled that a partner who acquires interests in a partnership in separate transactions must combine those interests and maintain a single adjusted tax basis for all of those interests.

Treatment of distributions

Distributions made by us to a unitholder generally will not be taxable to the unitholder, unless such distributions are of cash or marketable securities that are treated as cash and exceed the unitholder’s tax basis in its common units, in which case the unitholder generally will recognize gain taxable in the manner described below under “—Disposition of Common Units.”

Any reduction in a unitholder’s share of our “nonrecourse liabilities” (liabilities for which no partner bears the economic risk of loss) will be treated as a distribution by us of cash to that unitholder. A decrease in a unitholder’s percentage interest in us because of our issuance of additional common units may decrease such unitholder’s share of our nonrecourse liabilities. For purposes of the foregoing, a unitholder’s share of our nonrecourse liabilities generally will be based upon such unitholder’s share of the unrealized appreciation (or depreciation) in our assets, to the extent thereof, with any excess nonrecourse liabilities allocated based on the unitholder’s share of our profits. Please read “—Disposition of Common Units.”

Anon-pro rata distribution of money or property (including a deemed distribution as a result of the reallocation of our nonrecourse liabilities described above) may cause a unitholder to recognize ordinary income if the distribution reduces the unitholder’s share of our “unrealized receivables,” including depreciation recapture and substantially appreciated “inventory items,” both as defined in Section 751 of the Code (“Section 751 Assets”). To the extent of such reduction, the unitholder would be deemed to receive its proportionate share of the Section 751 Assets and exchange such assets with us in return for a portion of thenon-pro rata distribution. This deemed exchange will generally result in the unitholder’s recognition of ordinary income in an amount equal to the excess of (1) thenon-pro rata portion of that distribution over (2) the unitholder’s tax basis (typically zero) in the Section 751 Assets deemed to be relinquished in the exchange.

Limitations on deductibility of losses

A unitholder may not be entitled to deduct the full amount of loss we allocate to it because its share of our losses will be limited to the lesser of (i) the unitholder’s adjusted tax basis in its common units, and (ii) in the case of a unitholder that is an individual, estate, trust or certain types of closely-held corporations, the amount for which the unitholder is considered to be “at risk” with respect to our activities. A unitholder will be at risk to the extent of its adjusted tax basis in its common units, reduced by (1) any portion of that basis attributable to the unitholder’s share of our nonrecourse liabilities, (2) any portion of that basis representing amounts otherwise protected against loss because of a guarantee, stop loss agreement or similar arrangement, and (3) any amount of money the unitholder borrows to acquire or hold its common units, if the lender of those borrowed funds owns an interest in us, is related to another unitholder or can look only to the common units for repayment. A unitholder subject to the at risk limitation must recapture losses deducted in previous years to the extent that

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Material U.S. Federal Income Tax Consequences

distributions (including distributions deemed to result from a reduction in a unitholder’s share of nonrecourse liabilities) cause the unitholder’s at risk amount to be less than zero at the end of any taxable year.

Losses disallowed to a unitholder or recaptured as a result of the basis or at risk limitations will carry forward and will be allowable as a deduction in a later year to the extent that the unitholder’s adjusted tax basis or at risk amount, whichever is the limiting factor, is subsequently increased. Upon a taxable disposition of our common units, any gain recognized by a unitholder can be offset by losses that were previously suspended by the at risk limitation but not losses suspended by the basis limitation. Any loss previously suspended by the at risk limitation in excess of that gain can no longer be used, and will not be available to offset a unitholder’s salary or active business income.

In addition to the basis and at risk limitations, passive activity loss limitations limit the deductibility of losses incurred by individuals, estates, trusts, some closely-held corporations and personal service corporations from “passive activities” (generally, trade or business activities in which the taxpayer does not materially participate). The passive loss limitations are applied separately with respect to each publicly-traded partnership. Consequently, any passive losses we generate will be available to offset only passive income generated by us. Passive losses that exceed a unitholder’s share of the passive income we generate may be deducted in full when a unitholder disposes of all of its common units in a fully taxable transaction with an unrelated party. The passive activity loss rules are applied after other applicable limitations on deductions, including the at risk and basis limitations.

For taxpayers other than corporations in taxable years beginning after December 31, 2017, and before January 1, 2026, an “excess business loss” limitation further limits the deductibility of losses by such taxpayers. An excess business loss is the excess (if any) of a taxpayer’s aggregate deductions for the taxable year that are attributable to the trades or businesses of such taxpayer (determined without regard to the excess business loss limitation) over the aggregate gross income or gain of such taxpayer for the taxable year that is attributable to such trades or businesses plus a threshold amount. The threshold amount is equal to $250,000 or $500,000 for taxpayers filing a joint return. Disallowed excess business losses are treated as a net operating loss carryover to the following tax year. Any losses we generate that are allocated to a unitholder and not otherwise limited by the basis, at risk, or passive loss limitations will be included in the determination of such unitholder’s aggregate trade or business deductions. Consequently, any losses we generate that are not otherwise limited will only be available to offset a unitholder’s other trade or business income plus an amount ofnon-trade or business income equal to the applicable threshold amount. Thus, except to the extent of the threshold amount, our losses that are not otherwise limited may not offset a unitholder’snon-trade or business income (such as salaries, fees, interest, dividends and capital gains). This excess business loss limitation will be applied after the passive activity loss limitation.

Limitations on interest deductions

In general, we are entitled to a deduction for interest paid or accrued on indebtedness properly allocable to our trade or business during our taxable year. However, our deduction for this “business interest” is limited to the sum of our business interest income and 30% of our “adjusted taxable income.” For the purposes of this limitation, our adjusted taxable income is computed without regard to any business interest or business interest income, and in the case of taxable years beginning before January 1, 2022, any deduction allowable for depreciation, amortization, or depletion. This limitation is first applied at the partnership level and any deduction for business interest is taken into account in determining ournon-separately stated taxable income or loss. Then, in applying this business interest limitation at the partner level, the adjusted taxable income of each of our unitholders is determined without regard to

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Material U.S. Federal Income Tax Consequences

such unitholder’s distributive share of any of our items of income, gain, deduction, or loss and is increased by such unitholder’s distributive share of our excess taxable income, which is generally equal to the excess of 30% of our adjusted taxable income over the amount of our deduction for business interest for a taxable year.

To the extent our deduction for business interest is not limited, we will allocate the full amount of our deduction for business interest among our unitholders in accordance with their percentage interests in us. To the extent our deduction for business interest is limited, the amount of any disallowed deduction for business interest will also be allocated to each unitholder in accordance with their percentage interest in us, but such amount of “excess business interest” will not be currently deductible. Subject to certain limitations and adjustments to a unitholder’s basis in its common units, this excess business interest may be carried forward and deducted by a unitholder in a future taxable year.

In addition to this limitation on the deductibility of a partnership’s business interest, the deductibility of anon-corporate taxpayer’s “investment interest expense” is generally limited to the amount of that taxpayer’s “net investment income.” Investment interest expense includes:

interest on indebtedness allocable to property held for investment;

interest expense allocated against portfolio income; and

the portion of interest expense incurred to purchase or carry an interest in a passive activity to the extent allocable against portfolio income.

The computation of a unitholder’s investment interest expense will take into account interest on any margin account borrowing or other loan incurred to purchase or carry a unit. Net investment income includes gross income from property held for investment and amounts treated as portfolio income under the passive loss rules, less deductible expenses, other than interest, directly connected with the production of investment income. Net investment income does not include qualified dividend income (if applicable) or gains attributable to the disposition of property held for investment. A unitholder’s share of a publicly-traded partnership’s portfolio income and, according to the IRS, net passive income will be treated as investment income for purposes of the investment interest expense limitation.

Entity-level collections of unitholder taxes

If we are required or elect under applicable law to pay any federal, state, local ornon-U.S. tax on behalf of any current or former unitholder or our general partner, our partnership agreement authorizes us to treat the payment as a distribution of cash to the relevant unitholder or general partner. Where the tax is payable on behalf of all unitholders or we cannot determine the specific unitholder on whose behalf the tax is payable, our partnership agreement authorizes us to treat the payment as a distribution to all current unitholders. We are authorized to amend our partnership agreement in the manner necessary to maintain uniformity of intrinsic tax characteristics of common units and to adjust later distributions, so that after giving effect to these distributions, the priority and characterization of distributions otherwise applicable under our partnership agreement is maintained as nearly as is practicable. Payments by us as described above could give rise to an overpayment of tax on behalf of a unitholder, in which event the unitholder may be entitled to claim a refund of the overpayment amount. Please read “—Administrative Matters—Information Returns and Audit Procedures.” Each unitholder is urged to consult its tax advisor to determine the consequences to them of any tax payment we make on its behalf.

Allocation of income, gain, loss and deduction

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distributions are made in respect of the incentive distribution rights, gross income will be allocated to the recipients to the extent of such distributions. In addition, for any taxable year ending on or before December 31, 2020, holders of common units may be allocated additional gross operating income; provided that no such special allocation shall be made to the extent a purchaser of common units in this offering would be allocated an amount of U.S. federal taxable income on the common units purchased in this offering with respect to such taxable year that would exceed 20% of the cash distributed on the common units purchased in this offering with respect to such year.

Specified items of our income, gain, loss and deduction will be allocated under Section 704(c) of the Code (or the principles of Section 704(c) of the Code) to account for any difference between the adjusted tax basis and fair market value of our assets at the time such assets are contributed to us and at the time of any subsequent offering of our common units (a“Book-Tax Disparity”). As a result, the federal income tax burden associated with anyBook-Tax Disparity immediately prior to an offering will be borne by our partners holding interests in us prior to such offering. In addition, items of recapture income will be specially allocated to the extent possible (subject to the limitations described above) to the unitholder who was allocated the deduction giving rise to that recapture income in order to minimize the recognition of ordinary income by other unitholders.

It may not be administratively feasible to make the relevant adjustments to “book” basis and the relevant Section 704(c) allocations separately each time we issue units, particularly in the case of small or frequent unit issuances. If that is the case, we may use simplifying conventions to make those adjustments and allocations, which may include the aggregation of certain issuances of units. Our counsel, Vinson & Elkins, L.L.P., is unable to opine as to the validity of such conventions.

An allocation of items of our income, gain, loss or deduction, other than an allocation required by the Code to eliminate aBook-Tax Disparity, will be given effect for federal income tax purposes in determining a unitholder’s share of an item of income, gain, loss or deduction only if the allocation has “substantial economic effect.” In any other case, a unitholder’s share of an item will be determined on the basis of the unitholder’s interest in us, which will be determined by taking into account all the facts and circumstances, including (i) the unitholder’s relative contributions to us, (ii) the interests of all the partners in profits and losses, (iii) the interest of all the partners in cash flow and (iv) the rights of all the partners to distributions of capital upon liquidation. Vinson & Elkins L.L.P. is of the opinion that, with the exception of the issues described in “—Section 754 Election” and “—Disposition of Common Units—Allocations Between Transferors and Transferees,” allocations of income, gain, loss or deduction under our partnership agreement will be given effect for federal income tax purposes.

Treatment of securities loans

A unitholder whose common units are the subject of a securities loan (for example, a loan to a “short seller” to cover a short sale of common units) may be treated as having disposed of those common units. If so, such unitholder would no longer be treated for tax purposes as a partner with respect to those common units during the period of the loan and may recognize gain or loss as a result of such deemed disposition. As a result, during this period (i) any of our income, gain, loss or deduction allocated to those common units would not be reportable by the lending unitholder, and (ii) any cash distributions received by the lending unitholder as to those common units may be treated as ordinary taxable income.

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brokers from borrowing and lending its common units. The IRS has announced that it is studying issues relating to the tax treatment of short sales of partnership interests. Please read “—Disposition of Common Units—Recognition of Gain or Loss.”

Tax rates

Under current law, the highest marginal federal income tax rates for individuals applicable to ordinary income and long-term capital gains (generally, gains from the sale or exchange of certain investment assets held for more than one year) are 37% and 20%, respectively. These rates are subject to change by new legislation at any time.

In addition, a 3.8% net investment income tax applies to certain net investment income earned by individuals, estates, and trusts. For these purposes, net investment income generally includes a unitholder’s allocable share of our income and gain realized by a unitholder from a sale of common units. In the case of an individual, the tax will be imposed on the lesser of (i) the unitholder’s net investment income from all investments, or (ii) the amount by which the unitholder’s modified adjusted gross income exceeds $250,000 (if the unitholder is married and filing jointly or a surviving spouse), $125,000 (if the unitholder is married and filing separately) or $200,000 (if the unitholder is unmarried or in any other case). In the case of an estate or trust, the tax will be imposed on the lesser of (i) undistributed net investment income, or (ii) the excess adjusted gross income over the dollar amount at which the highest income tax bracket applicable to an estate or trust begins.

For taxable years beginning after December 31, 2017 and ending on or before December 31, 2025, an individual unitholder is entitled to a deduction equal to 20% of his or her allocable share of our “qualified business income.” For purposes of this deduction, our “qualified business income” is equal to the sum of:

the net amount of our U.S. items of income, gain, deduction, and loss to the extent such items are included or allowed in the determination of taxable income for the year, excluding, however, certain specified types of passive investment income (such as capital gains and dividends) and certain payments made to the unitholder for services rendered to the Partnership; and

any gain recognized upon a disposition of our common units to the extent such gain is attributable to Section 751 Assets, such as depreciation recapture and our “inventory items,” and is thus treated as ordinary income under Section 751 of the Code.

Section 754 election

We have made the election permitted by Section 754 of the Code that permits us to adjust the tax basis in each of our assets as to specific purchasers of our common units under Section 743(b) of the Code to reflect the unit purchase price upon subsequent purchases of common units. That election is irrevocable without the consent of the IRS. The Section 743(b) adjustment separately applies to a unitholder who purchases common units from another unitholder based upon the values and adjusted tax basis of each of our assets at the time of the relevant unit purchase, and the adjustment will reflect the purchase price paid. The Section 743(b) adjustment does not apply to a person who purchases common units directly from us. For purposes of this discussion, a unitholder’s basis in our assets will be considered to have two components: (1) its share of the tax basis in our assets as to all unitholders and (2) its Section 743(b) adjustment to that tax basis (which may be positive or negative).

Under our partnership agreement, we are authorized to take a position to preserve the uniformity of common units even if that position is not consistent with applicable Treasury Regulations. A literal

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application of Treasury Regulations governing a Section 743(b) adjustment attributable to properties depreciable under Section 167 of the Code may give rise to differences in the taxation of unitholders purchasing common units from us and unitholders purchasing from other unitholders. If we have any such properties, we intend to adopt methods employed by other publicly traded partnerships to preserve the uniformity of common units, even if inconsistent with existing Treasury Regulations, and Vinson & Elkins L.L.P. has not opined on the validity of this approach. Please read “—Uniformity of Common Units.”

The IRS may challenge the positions we adopt with respect to depreciating or amortizing the Section 743(b) adjustment to preserve the uniformity of common units due to the lack of controlling authority. Because a unitholder’s adjusted tax basis for its common units is reduced by its share of our items of deduction or loss, any position we take that understates deductions will overstate a unitholder’s tax basis in its common units, and may cause the unitholder to understate gain or overstate loss on any sale of such common units. Please read “—Disposition of Common Units—Recognition of Gain or Loss.” If a challenge to such treatment were sustained, the gain from the sale of common units may be increased without the benefit of additional deductions.

The calculations involved in the Section 754 election are complex and are made on the basis of assumptions as to the value of our assets and other matters. The IRS could seek to reallocate some or all of any Section 743(b) adjustment we allocated to our assets subject to depreciation to goodwill or nondepreciable assets. Goodwill, as an intangible asset, is generally amortizable over a longer period of time or under a less accelerated method than our tangible assets. We cannot assure any unitholder that the determinations we make will not be successfully challenged by the IRS or that the resulting deductions will not be reduced or disallowed altogether. Should the IRS require a different tax basis adjustment to be made, and should, in our opinion, the expense of compliance exceed the benefit of the election, we may seek permission from the IRS to revoke our Section 754 election. If permission is granted, a subsequent purchaser of common units may be allocated more income than it would have been allocated had the election not been revoked.

TAX TREATMENT OF OPERATIONS

Accounting method and taxable year

We use the year ending December 31 as our taxable year and the accrual method of accounting for federal income tax purposes. Each unitholder will be required to include in its tax return its share of our income, gain, loss and deduction for each taxable year ending within or with its taxable year. In addition, a unitholder who has a taxable year ending on a date other than December 31 and who disposes of all of its common units following the close of our taxable year but before the close of its taxable year must include its share of our income, gain, loss and deduction in income for its taxable year, with the result that it will be required to include in income for its taxable year its share of more than twelve months of our income, gain, loss and deduction. Please read “—Disposition of Common Units—Allocations Between Transferors and Transferees.”

Tax basis, depreciation and amortization

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ordinary income rather than capital gain. Similarly, a unitholder who has taken cost recovery or depreciation deductions with respect to property we own will likely be required to recapture some or all of those deductions as ordinary income upon a sale of its interest in us. Please read “—Tax Consequences of Unit Ownership—Allocation of Income, Gain, Loss and Deduction” and “—Disposition of Common Units—Recognition of Gain or Loss.”

For tax purposes, the costs we incur in offering and selling our common units (called “syndication expenses”) must be capitalized and cannot be deducted currently, ratably or upon our termination. While there are uncertainties regarding the classification of certain costs as organization expenses, which may be amortized by us, and as syndication expenses, which may not be amortized by us, the underwriting discounts and commissions we incur will be treated as syndication expenses. Please read “Disposition of Common Units—Recognition of Gain or Loss.”

We are allowed a first-year bonus depreciation deduction equal to 100% of the adjusted basis of certain depreciable property acquired and placed in service after September 27, 2017 and before January 1, 2023. For property placed in service during subsequent years, the deduction is phased down by 20% per year until December 31, 2026. This depreciation deduction applies to both new and used property. However, use of the deduction with respect to used property is subject to certain anti-abuse restrictions, including the requirement that the property be acquired from an unrelated party. We can elect to forgo the depreciation bonus and use the alternative depreciation system for any class of property for a taxable year. Under a transition rule, we can also elect to apply a 50% bonus depreciation deduction instead of the 100% deduction for our first taxable year ending after September 27, 2017.

Valuation and tax basis of each of our properties

The federal income tax consequences of the ownership and disposition of common units will depend in part on our estimates of the relative fair market values and the tax basis of each of our assets. Although we may from time to time consult with professional appraisers regarding valuation matters, we will make many of the relative fair market value estimates ourselves. These estimates and determinations of tax basis are subject to challenge and will not be binding on the IRS or the courts. If the estimates of fair market value or tax basis are later found to be incorrect, the character and amount of items of income, gain, loss or deduction previously reported by a unitholder could change, and such unitholder could be required to adjust its tax liability for prior years and incur interest and penalties with respect to those adjustments.

DISPOSITION OF COMMON UNITS

Recognition of gain or loss

A unitholder will be required to recognize gain or loss on a sale or exchange of a unit equal to the difference, if any, between the unitholder’s amount realized and the adjusted tax basis in the unit sold. A unitholder’s amount realized generally will equal the sum of the cash and the fair market value of other property it receives plus its share of our nonrecourse liabilities with respect to the unit sold or exchanged. Because the amount realized includes a unitholder’s share of our nonrecourse liabilities, the gain recognized on the sale or exchange of a unit could result in a tax liability in excess of any cash received from such sale or exchange.

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recognized on the disposition of common units will be separately computed and taxed as ordinary income or loss under Section 751 of the Code to the extent attributable to Section 751 Assets, such as depreciation recapture and our “inventory items,” regardless of whether such inventory item has substantially appreciated in value. Ordinary income attributable to Section 751 Assets may exceed net taxable gain realized on the sale or exchange of a unit and may be recognized even if there is a net taxable loss realized on the sale or exchange of a unit. Thus, a unitholder may recognize both ordinary income and capital gain or loss upon a sale or exchange of a unit. Net capital loss may offset capital gains and, in the case of individuals, up to $3,000 of ordinary income per year.

For purposes of calculating gain or loss on the sale or exchange of a unit, the unitholder’s adjusted tax basis will be adjusted by its allocable share of our income or loss in respect of its unit for the year of the sale. Furthermore, as described above, the IRS has ruled that a partner who acquires interests in a partnership in separate transactions must combine those interests and maintain a single adjusted tax basis for all those interests. Upon a sale or other disposition of less than all of those interests, a portion of that tax basis must be allocated to the interests sold using an “equitable apportionment” method, which generally means that the tax basis allocated to the interest sold equals an amount that bears the same relation to the partner’s tax basis in its entire interest in the partnership as the value of the interest sold bears to the value of the partner’s entire interest in the partnership.

Treasury Regulations under Section 1223 of the Code allow a selling unitholder who can identify common units transferred with an ascertainable holding period to elect to use the actual holding period of the common units transferred. Thus, according to the ruling discussed in the paragraph above, a unitholder will be unable to select high or low basis common units to sell or exchange as would be the case with corporate stock, but, according to the Treasury Regulations, such unitholder may designate specific common units sold for purposes of determining the holding period of the common units transferred. A unitholder electing to use the actual holding period of any unit transferred must consistently use that identification method for all subsequent sales or exchanges of our common units. A unitholder considering the purchase of additional common units or a sale or exchange of common units purchased in separate transactions is urged to consult its tax advisor as to the possible consequences of this ruling and application of the Treasury Regulations.

Specific provisions of the Code affect the taxation of some financial products and securities, including partnership interests, by treating a taxpayer as having sold an “appreciated” financial position, including a partnership interest with respect to which gain would be recognized if it were sold, assigned or terminated at its fair market value, in the event the taxpayer or a related person enters into:

a short sale;

an offsetting notional principal contract; or

a futures or forward contract with respect to the partnership interest or substantially identical property.

Moreover, if a taxpayer has previously entered into a short sale, an offsetting notional principal contract or a futures or forward contract with respect to the partnership interest, the taxpayer will be treated as having sold that position if the taxpayer or a related person then acquires the partnership interest or substantially identical property. The Secretary of the Treasury is authorized to issue Treasury Regulations that treat a taxpayer that enters into transactions or positions that have substantially the same effect as the preceding transactions as having constructively sold the financial position. Please read “—Tax Consequences of Unit Ownership—Treatment of Securities Loans.”

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Allocations between transferors and transferees

In general, our taxable income or loss will be determined annually, will be prorated on a monthly basis and will be subsequently apportioned among the unitholders in proportion to the number of common units owned by each of them as of the opening of the applicable exchange on the first business day of the month (the “Allocation Date”). Nevertheless, we allocate certain deductions for depreciation of capital additions based upon the date the underlying property is placed in service, and gain or loss realized on a sale or other disposition of our assets or, in the discretion of the general partner, any other extraordinary item of income, gain, loss or deduction will be allocated among the unitholders on the Allocation Date in the month in which such income, gain, loss or deduction is recognized. As a result, a unitholder transferring common units may be allocated income, gain, loss and deduction realized after the date of transfer.

Although simplifying conventions are contemplated by the Code and most publicly traded partnerships use similar simplifying conventions, existing Treasury Regulations do not specifically authorize the use of the proration method we have adopted. Accordingly, Vinson & Elkins L.L.P. is unable to opine on the validity of this method of allocating income and deductions between transferee and transferor unitholders. If the IRS determines that this method is not allowed under the Treasury Regulations our taxable income or losses could be reallocated among our unitholders. Under our partnership agreement, we are authorized to revise our method of allocation between transferee and transferor unitholders, as well as among unitholders whose interests vary during a taxable year, to conform to a method permitted under the Treasury Regulations.

A unitholder who disposes of common units prior to the record date set for a cash distribution for that quarter will be allocated items of our income, gain, loss and deduction attributable to the month of disposition (and any other month during the quarter to which such cash distribution relates and the holder held common units on the first day of such month) but will not be entitled to receive a cash distribution for that period.

Notification requirements

A unitholder who sells or exchanges any of its common units is generally required to notify us in writing of that transaction within 30 days after the transaction (or, if earlier, January 15 of the year following the transaction in the case of a seller). Upon receiving such notifications, we are required to notify the IRS of the transaction and to furnish specified information to the transferor and transferee. Failure to notify us of a transfer of common units may, in some cases, lead to the imposition of penalties. However, these reporting requirements do not apply to a sale by an individual who is a citizen of the United States and who effects the sale or exchange through a broker who will satisfy such requirements.

UNIFORMITY OF COMMON UNITS

Because we cannot match transferors and transferees of common units and for other reasons, we must maintain uniformity of the economic and tax characteristics of the common units to a purchaser of these common units. As a result of the need to preserve uniformity, we may be unable to completely comply with a number of federal income tax requirements. Anynon-uniformity could have a negative impact on the value of our common units. Please read “—Tax Consequences of Unit Ownership—Section 754 Election.”

Our partnership agreement permits our general partner to take positions in filing our tax returns that preserve the uniformity of our common units. These positions may include reducing the depreciation,

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amortization or loss deductions to which a unitholder would otherwise be entitled or reporting a slower amortization of Section 743(b) adjustments for some unitholders than that to which they would otherwise be entitled. Vinson & Elkins L.L.P. is unable to opine as to the validity of such filing positions.

A unitholder’s adjusted tax basis in common units is reduced by its share of our deductions (whether or not such deductions were claimed on an individual income tax return) so that any position that we take that understates deductions will overstate the unitholder’s basis in its common units, and may cause the unitholder to understate gain or overstate loss on any sale of such common units. Please read “—Disposition of Common Units—Recognition of Gain or Loss” and “—Tax Consequences of Unit Ownership—Section 754 Election” above. The IRS may challenge one or more of any positions we take to preserve the uniformity of our common units. If such a challenge were sustained, the uniformity of common units might be affected, and, under some circumstances, the gain from the sale of our common units might be increased without the benefit of additional deductions.

In addition, as described above at “—Tax Consequences of Unit Ownership—Allocation of Income, Gain, Loss and Deduction,” if we aggregate multiple issuances of units for purposes of making adjustments to “book” basis and related tax allocations, we will treat each of our units as having the same capital account balance, regardless of the price actually paid by each purchaser of units in the aggregated offerings. Our counsel, Vinson & Elkins L.L.P., is unable to opine as to the validity of such an approach. We do not expect the number of affected units, or the differences between the purchase price of a unit and the initial capital account balance assigned to the unit, to be material, and we do not expect this convention to have a material effect upon the trading of our units.

TAX-EXEMPT ORGANIZATIONS AND OTHER INVESTORS

Ownership of our common units by employee benefit plans and othertax-exempt organizations, as well as bynon-resident alien individuals,non-U.S. corporations and othernon-U.S. persons (collectively,“Non-U.S. Unitholders”) raises issues unique to those investors and, as described below, may have substantial adverse tax consequences to them. Each prospective unitholder that is atax-exempt entity or aNon-U.S. Unitholder should consult its tax advisors before investing in our common units.

Employee benefit plans and most othertax-exempt organizations, including IRAs and other retirement plans, are subject to federal income tax on unrelated business taxable income. Virtually all of our income will be unrelated business taxable income and will be taxable to atax-exempt unitholder.Tax-exempt unitholders with more than one unrelated trade or business (including by attribution from the Partnership to the extent it is engaged in one or more unrelated trade or business) are required to separately compute their unrelated business taxable income with respect to each unrelated trade or business (including for purposes of determining any net operating loss deduction). As a result, it may not be possible fortax-exempt unitholders to utilize losses from an investment in the Partnership to offset unrelated business taxable income from another unrelated trade or business and vice versa.

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Moreover, under rules applicable to publicly-traded partnerships, distributions toNon-U.S. Unitholders are subject to withholding at the highest applicable effective tax rate. EachNon-U.S. Unitholder must obtain a taxpayer identification number from the IRS and submit that number to our transfer agent on a FormW-8BEN orW-8BEN-E (or other applicable or successor form) in order to obtain credit for these withholding taxes.

In addition, if aNon-U.S. Unitholder is classified as anon-U.S. corporation, it will be treated as engaged in a United States trade or business and may be subject to the U.S. branch profits tax at a rate of 30%, in addition to regular U.S. federal income tax, on its share of our income and gain as adjusted for changes in the foreign corporation’s “U.S. net equity” to the extent reflected in the corporation’s earnings and profits. That tax may be reduced or eliminated by an income tax treaty between the United States and the country in which the foreign corporate unitholder is a “qualified resident.” In addition, this type of unitholder is subject to special information reporting requirements under Section 6038C of the Code.

ANon-U.S. Unitholder who sells or otherwise disposes of a unit will be subject to U.S. federal income tax on gain realized from the sale or disposition of that unit to the extent the gain is effectively connected with a U.S. trade or business of theNon-U.S. Unitholder. Gain realized by aNon-U.S. Unitholder from the sale of its interest in a partnership that is engaged in a trade or business in the United States will be considered to be “effectively connected” with a U.S. trade or business to the extent that gain that would be recognized upon a sale by the partnership of all of its assets would be “effectively connected” with a U.S. trade or business. Thus, all of aNon-U.S. Unitholder’s gain from the sale or other disposition of our common units would be treated as effectively connected with a unitholder’s indirect U.S. trade or business constituted by its investment in us and would be subject to U.S. federal income tax. As a result of the effectively connected income rules described above, the exclusion from U.S. taxation under the Foreign Investment in Real Property Tax Act for gain from the sale of partnership common units regularly traded on an established securities market will not prevent aNon-U.S. Unitholder from being subject to U.S. federal income tax on gain from the sale or disposition of its common units to the extent such gain is effectively connected with a U.S. trade or business. We expect all of the gain from the sale or disposition of our common units to be treated as effectively connected with a U.S. trade or business.

Moreover, the transferee of an interest in a partnership that is engaged in a U.S. trade or business is generally required to withhold 10% of the amount realized by the transferor unless the transferor certifies that it is not a foreign person, and we are required to deduct and withhold from the transferee amounts that should have been withheld by the transferees but were not withheld. Because the “amount realized” includes a partner’s share of the partnership’s liabilities, 10% of the amount realized could exceed the total cash purchase price for the common units. For this and other reasons, the IRS has suspended the application of this withholding rule to open market transfers of interest in publicly traded partnerships, pending promulgation of regulations that address the amount to be withheld, the reporting necessary to determine such amount and the appropriate party to withhold such amounts, but it is not clear if or when such regulations will be issued.

ADMINISTRATIVE MATTERS

Information returns and audit procedures

We intend to furnish to each unitholder, within 90 days after the close of each taxable year, specific tax information, including a ScheduleK-1, which describes its share of our income, gain, loss and deduction for our preceding taxable year. In preparing this information, which will not be reviewed by counsel, we will take various accounting and reporting positions, some of which have been mentioned earlier, to

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determine each unitholder’s share of income, gain, loss and deduction. We cannot assure our unitholders that those positions will yield a result that conforms to all of the requirements of the Code, Treasury Regulations or administrative interpretations of the IRS.

The IRS may audit our federal income tax information returns. Neither we nor Vinson & Elkins L.L.P. can assure prospective unitholders that the IRS will not successfully challenge the positions we adopt, and such a challenge could adversely affect the value of our common units. Adjustments resulting from an IRS audit may require each unitholder to adjust a prior year’s tax liability, and may result in an audit of the unitholder’s own return. Any audit of a unitholder’s return could result in adjustments unrelated to our returns.

Publicly-traded partnerships are treated as entities separate from their owners for purposes of federal income tax audits, judicial review of administrative adjustments by the IRS and tax settlement proceedings. The tax treatment of partnership items of income, gain, loss and deduction are determined in a partnership proceeding rather than in separate proceedings for each of the partners. Pursuant to the Bipartisan Budget Act of 2015, for taxable years beginning after December 31, 2017, if the IRS makes audit adjustments to our income tax returns, it may assess and collect any taxes (including any applicable penalties and interest) resulting from such audit adjustment directly from us, unless we elect to have our general partner, unitholders and former unitholders take any audit adjustment into account in accordance with their interests in us during the taxable year under audit. Similarly, for such taxable years, if the IRS makes audit adjustments to income tax returns filed by an entity in which we are a member or partner, it may assess and collect any taxes (including penalties and interest) resulting from such audit adjustment directly from such entity.

Generally, we expect to elect to have our general partner, unitholders and former unitholders take any such audit adjustment into account in accordance with their interests in us during the taxable year under audit, but there can be no assurance that such election will be effective in all circumstances. If we are unable or if it is not economical to have our general partner, unitholders and former unitholders take such audit adjustment into account in accordance with their interests in us during the taxable year under audit, our then current unitholders may bear some or all of the tax liability resulting from such audit adjustment, even if such unitholders did not own our common units during the taxable year under audit. If, as a result of any such audit adjustment, we are required to make payments of taxes, penalties or interest, our cash available for distribution to our unitholders might be substantially reduced. These rules are not applicable for taxable years beginning on or prior to December 31, 2017. Congress has proposed changes to the Bipartisan Budget Act, and we anticipate that amendments may be made. Accordingly, the manner in which these rules may apply to us in the future is uncertain.

Additionally, pursuant to the Bipartisan Budget Act of 2015, the Code will no longer require that we designate a Tax Matters Partner. Instead, for taxable years beginning after December 31, 2017, we will be required to designate a partner, or other person, with a substantial presence in the United States as the partnership representative (“Partnership Representative”). The Partnership Representative will have the sole authority to act on our behalf for purposes of, among other things, federal income tax audits and judicial review of administrative adjustments by the IRS. If we do not make such a designation, the IRS can select any person as the Partnership Representative. We currently anticipate that we will designate our general partner as the Partnership Representative. Further, any actions taken by us or by the Partnership Representative on our behalf with respect to, among other things, federal income tax audits and judicial review of administrative adjustments by the IRS, will be binding on us and all of our unitholders.

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Material U.S. Federal Income Tax Consequences

Additional withholding requirements

Withholding taxes may apply to certain types of payments made to “foreign financial institutions” (as specially defined in the Code) and certain othernon-U.S. entities. Specifically, a 30% withholding tax may be imposed on interest, dividends and other fixed or determinable annual or periodic gains, profits and income from sources within the United States (“FDAP Income”), or gross proceeds from the sale or other disposition of any property of a type which can produce interest or dividends from sources within the United States (“Gross Proceeds”) paid to a foreign financial institution or to a“non-financial foreign entity” (as specially defined in the Code), unless (i) the foreign financial institution undertakes certain diligence and reporting, (ii) thenon-financial foreign entity either certifies it does not have any substantial U.S. owners or furnishes identifying information regarding each substantial U.S. owner or (iii) the foreign financial institution ornon-financial foreign entity otherwise qualifies for an exemption from these rules. If the payee is a foreign financial institution and is subject to the diligence and reporting requirements in clause (i) above, it must enter into an agreement with the U.S. Department of the Treasury requiring, among other things, that it undertake to identify accounts held by certain U.S. persons or U.S.-owned foreign entities, annually report certain information about such accounts, and withhold 30% on payments to noncompliant foreign financial institutions and certain other account holders. Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing these requirements may be subject to different rules.

Generally these rules apply to current payments of FDAP Income and will apply to payments of relevant Gross Proceeds made on or after January 1, 2019. Thus, to the extent we have FDAP Income or we have Gross Proceeds on or after January 1, 2019 that are not treated as effectively connected with a U.S. trade or business (please read“—Tax-Exempt Organizations and Other Investors”), a unitholder that is a foreign financial institution or certain othernon-U.S. entity, or a person that holds its common units through such foreign entities, may be subject to withholding on distributions they receive from us, or its distributive share of our income, pursuant to the rules described above.

Each prospective unitholder should consult its own tax advisors regarding the potential application of these withholding provisions to its investment in our common units.

Nominee reporting

Persons who hold an interest in us as a nominee for another person are required to furnish to us:

the name, address and taxpayer identification number of the beneficial owner and the nominee;

a statement regarding whether the beneficial owner is:

○

anon-U.S. person;

○

anon-U.S. government, an international organization or any wholly-owned agency or instrumentality of either of the foregoing; or

○

atax-exempt entity;

the amount and description of common units held, acquired or transferred for the beneficial owner; and

specific information including the dates of acquisitions and transfers, means of acquisitions and transfers, and acquisition cost for purchases, as well as the amount of net proceeds from sales.

S-21

Material U.S. Federal Income Tax Consequences

broker or financial institution acquires, holds or transfers for its own account. A penalty per failure, with a significant maximum penalty per calendar year, is imposed by the Code for failure to report that information to us. The nominee is required to supply the beneficial owner of our common units with the information furnished to us.

Accuracy-related penalties

Certain penalties may be imposed as a result of an underpayment of tax that is attributable to one or more specified causes, including negligence or disregard of rules or regulations, substantial understatements of income tax and substantial valuation misstatements. No penalty will be imposed, however, for any portion of an underpayment if it is shown that there was a reasonable cause for the underpayment of that portion and that the taxpayer acted in good faith regarding the underpayment of that portion. We do not anticipate that any accuracy-related penalties will be assessed against us.

STATE, LOCAL AND OTHER TAX CONSIDERATIONS

In addition to federal income taxes, unitholders may be subject to other taxes, including state and local income taxes, unincorporated business taxes and estate, inheritance or intangibles taxes that may be imposed by the various jurisdictions in which we conduct business or own property now or in the future or in which the unitholder is a resident. We conduct business or own property in Kentucky, Louisiana, and Texas; Kentucky and Louisiana currently impose an income tax on individuals, corporations and other entities. As we make acquisitions or expand our business, we may own property or conduct business in additional states that impose a personal income tax. Although an analysis of those various taxes is not presented here, each prospective unitholder should consider the potential impact of such taxes on its investment in us.

A unitholder may be required to file income tax returns and pay income taxes in some or all of the jurisdictions in which we do business or own property, though such unitholder may not be required to file a return and pay taxes in certain jurisdictions because its income from such jurisdictions falls below the jurisdiction’s filing and payment requirement. Further, a unitholder may be subject to penalties for a failure to comply with any filing or payment requirement applicable to such unitholder. Some of the jurisdictions may require us, or we may elect, to withhold a percentage of income from amounts to be distributed to a unitholder who is not a resident of the jurisdiction. Withholding, the amount of which may be greater or less than a particular unitholder’s income tax liability to the jurisdiction, generally does not relieve a nonresident unitholder from the obligation to file an income tax return.

IT IS THE RESPONSIBILITY OF EACH UNITHOLDER TO INVESTIGATE THE LEGAL AND TAX CONSEQUENCES, UNDER THE LAWS OF PERTINENT JURISDICTIONS, OF HIS INVESTMENT IN US. WE STRONGLY RECOMMEND THAT EACH PROSPECTIVE UNITHOLDER CONSULT, AND DEPEND UPON, ITS OWN TAX COUNSEL OR OTHER ADVISOR WITH REGARD TO THOSE MATTERS. FURTHER, IT IS THE RESPONSIBILITY OF EACH UNITHOLDER TO FILE ALL STATE, LOCAL ANDNON-U.S., AS WELL AS U.S. FEDERAL TAX RETURNS THAT MAY BE REQUIRED OF IT. VINSON & ELKINS L.L.P. HAS NOT RENDERED AN OPINION ON THE STATE, LOCAL, ALTERNATIVE MINIMUM TAX ORNON-U.S. TAX CONSEQUENCES OF AN INVESTMENT IN US.

S-22

Plan of Distribution

We have entered into an equity distribution agreement with UBS Securities LLC, Barclays Capital Inc., Citigroup Global Markets Inc., Deutsche Bank Securities Inc., Merrill Lynch, Pierce, Fenner & Smith Incorporated, RBC Capital Markets, LLC and Wells Fargo Securities, LLC, as managers, under which we may offer and sell common units having an aggregate offering amount of up to $50,000,000 from time to time through one or more of such managers. We previously filed the equity distribution agreement as an exhibit to a Current Report on Form8-K, which is incorporated by reference in this prospectus supplement. Sales of the common units, if any, made under the equity distribution agreement will be made by means of ordinary brokers’ transactions through the facilities of the NYSE, any other national securities exchange or facility thereof, a trading facility of a national securities association or an alternate trading system, at market prices prevailing at the time of sale or negotiated prices, to or through a market maker or directly on or through an electronic communication network, in block transactions or as otherwise agreed with the managers. The managers will not engage in any transactions that stabilize the price of our common units.

Under the terms of the equity distribution agreement, we also may sell common units to any manager as principal for its own account at a price agreed upon at the time of sale. If we sell common units to any manager as principal, we will enter into a separate terms agreement with that manager and we will describe that agreement in a separate prospectus supplement or pricing supplement.

The managers are not required to sell any specific number or dollar amount of common units but will use their commercially reasonable efforts to sell the common units offered pursuant to this prospectus supplement on a daily basis or as otherwise agreed upon by us and a manager. We will designate the maximum amount of common units to be sold through a manager, on a daily basis or otherwise as we and a manager agree. We will submit orders to only one manager relating to the sale of our common units on any given day. We may instruct such manager not to sell common units if the sales cannot be effected at or above the price designated by us in any such instruction. Either we or any manager may suspend the offering of common units by such manager pursuant to the equity distribution agreement by notifying the other party.

The commission to be paid to any manager for common units sold through it pursuant to the equity distribution agreement shall be at a commission rate of up to 2.0% of the gross sales price. The remaining sales proceeds, after deducting the applicable commission and any expenses payable by us and any transaction fees imposed by any governmental or self-regulatory organization in connection with the sales, will equal our net proceeds from the sale of the common units (the “Net Proceeds”).

Settlement for sales of common units will occur on the second business day following the date on which any sales were made in return for payment of the net proceeds to us. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

Each manager will provide to us written confirmation following the close of trading on the NYSE each day in which common units are sold by it as our agent under the equity distribution agreement. Each confirmation will include the aggregate number of common units sold on that day, the Net Proceeds to us and the aggregate compensation payable by us to such manager. We will report at least quarterly the number of common units sold through the managers under the equity distribution agreement, the Net Proceeds to us and the compensation paid by us to the managers in connection with the sales of the common units during the relevant quarter.

S-23

Plan of Distribution

In connection with the sale of the common units on our behalf, the managers may be deemed to be “underwriters” within the meaning of the Securities Act of 1933, as amended (the “Securities Act”), and the compensation paid to the managers may be deemed to be underwriting commissions or discounts. We and our general partner have agreed to provide indemnification and contribution to the managers against certain liabilities, including civil liabilities under the Securities Act. We have also agreed to reimburse the managers for certain of their expenses.

The managers and their respective affiliates are full service financial institutions engaged in various activities, which may include sales and trading, commercial and investment banking, advisory, investment management, principal investment, hedging, marketing making, brokerage and other financial andnon-financial activities and services. Certain of the managers and their respective affiliates have in the past, and may in the future, perform investment banking, commercial banking, advisory and other services for us and our respective affiliates from time to time for which they have received, and may in the future receive, customary fees and expenses. For example, affiliates of certain of the managers are lenders or agents for the lenders under certain revolving or term loan credit agreements of Westlake.

In the ordinary course of their various business activities, the managers and their respective affiliates, officers, directors and employees may make or hold a broad array of investments, including serving as counterparties to certain derivative and hedging arrangements, and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investment and securities activities may involve assets, securities and instruments of ours or our affiliates. The managers and their affiliates may also communicate independent investment recommendations, market color or trading ideas or publish or express independent research views in respect of such assets, securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such assets, securities and instruments.

Because the Financial Industry Regulatory Authority, Inc. (“FINRA”) views the common units offered hereby as interests in a direct participation program, this offering is being made in compliance with Rule 2310 of the FINRA Rules.

If we or any of the managers has reason to believe the exemptive provisions set forth in Rule 101(c)(1) of Regulation M under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), are not satisfied with respect to our common units, that party will promptly notify the other.

The offering of common units pursuant to the equity distribution agreement will terminate upon the earlier of (1) the sale of all common units subject to the equity distribution agreement or (2) the termination of the equity distribution agreement by us or by all of the managers.

SELLING RESTRICTIONS

Notice to prospective investors in Australia

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission, in relation to the offering. This prospectus supplement does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the “Corporations Act”), and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

S-24

Plan of Distribution

Any offer in Australia of the common units may only be made to persons (the “Exempt Investors”) who are:

(a)

“sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act; and

(b)

“wholesale clients” (within the meaning of section 761G of the Corporations Act),

so that it is lawful to offer the common units without disclosure to investors under Chapters 6D and 7 of the Corporations Act.

The common units applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapters 6D and 7 of the Corporations Act would not be required pursuant to an exemption under both section 708 and Subdivision B of Division 2 of Part 7.9 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapters 6D and 7 of the Corporations Act. Any person acquiring common units must observe such Australianon-sale restrictions.

This prospectus supplement contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

Notice to prospective investors in Hong Kong

The common units have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made under that Ordinance; or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the common units has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to common units which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the Securities and Futures Ordinance and any rules made under that Ordinance.

Notice to prospective investors in Singapore

This prospectus supplement has not been and will not be registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the common units may not be circulated or distributed, nor may the common units be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the “SFA”), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

S-25

Plan of Distribution

Where the common units are subscribed or purchased under Section 275 of the SFA by a relevant person which is: (1) a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or (2) a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor, securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the common units pursuant to an offer made under Section 275 of the SFA except: (a) to an institutional investor or to a relevant person defined in Section 275(2) of the SFA, or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA; (b) where no consideration is or will be given for the transfer; (c) where the transfer is by operation of law; (d) as specified in Section 276(7) of the SFA; or (e) as specified in Regulation 32 of the Securities and Futures (Offers of Investments) (Shares and Debentures) Regulations 2005 of Singapore.

Singapore Securities and Futures Act Product Classification—Solely for the purposes of its obligations pursuant to Sections 309B(1)(a) and 309B(1)(c) of the SFA, we have determined, and hereby notify all relevant persons (as defined in Section 309A of the SFA) that the common units are “prescribed capital markets products” (as defined in the Securities and Futures (Capital Markets Products) Regulations 2018) and Excluded Investment Products (as defined in MAS Notice SFA04- N12: Notice on the Sale of Investment Products and MAS NoticeFAA-N16: Notice on Recommendations on Investment Products).

S-26

Legal Matters

The validity of the common units offered hereby will be passed upon for us by Vinson & Elkins L.L.P., Houston, Texas. Certain legal matters in connection with the common units offered hereby will be passed upon for the managers by Baker Botts L.L.P., Houston, Texas.

Experts

The financial statements and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) incorporated in this prospectus by reference to the Annual Report on Form10-K for the year ended December 31, 2017 have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

Forward-Looking Statements

Certain of the statements included in or incorporated by reference into this prospectus are forward-looking statements. All such statements, other than statements of historical facts, that address activities, events or developments that we expect, project, believe or anticipate will or may occur in the future are forward-looking statements, including, without limitation, statements regarding our plans, strategies, prospects and expectations concerning our business, results of operations and financial conditions. Forward-looking statements can be identified by the use of words such as “believes,” “intends,” “may,” “should,” “could,” “anticipates,” “expects,” “will” or comparable terminology, or by discussions of strategies or trends. These forward-looking statements are based on our current expectations and beliefs concerning future developments and their potential effect on us. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give any assurances that these expectations will prove to be correct. All comments concerning our expectations for future revenues and operating results are based on our forecasts for our existing operations and do not include the potential impact of any future acquisitions. Our forward-looking statements involve significant risks and uncertainties (some of which are beyond our control) and assumptions that could cause actual results to differ materially from our historical experience and our present expectations or projections. Known material factors that could cause our actual results to differ materially from those in these forward-looking statements are described below and in “Risk Factors” in this prospectus supplement, or the accompanying base prospectus or the documents we incorporate by reference herein or therein, as applicable. Forward-looking statements relate to matters such as:

the amount of ethane that we are able to process, which could be adversely affected by, among other things, operating difficulties;

the volume of ethylene that we are able to sell;

the price at which we are able to sell ethylene;

industry market outlook, including prices and margins in third-party ethylene andco-products sales;

the parties to whom we will sell ethylene and on what basis;

volumes of ethylene that Westlake may purchase, in addition to the minimum commitment under the ethylene sales agreement between OpCo and Westlake;

S-27

Forward-Looking Statements

timing, funding and results of capital projects;

our intended minimum quarterly distributions and the manner of making such distributions;

our ability to meet our liquidity needs;

timing of and amount of capital expenditures;

potential loans from Westlake to OpCo to fund OpCo’s expansion capital expenditures in the future;

expected mitigation of exposure to commodity price fluctuations;

turnaround activities and the variability of OpCo’s cash flow;

compliance with present and future environmental regulations and costs associated with environmentally related penalties, capital expenditures, remedial actions and proceedings, including any new laws, regulations or treaties that may come into force to limit or control carbon dioxide and other greenhouse gas emissions or to address other issues of climate change; and

effects of pending legal proceedings.

We have based these statements on assumptions and analysis in light of our experience and perception of historical trends, current conditions, expected future developments and other factors we believe were appropriate in the circumstances when the statements were made. Forward-looking statements by their nature involve substantial risks and uncertainties that could significantly impact expected results, and actual future results could differ materially from those described in such statements. These statements are subject to a number of assumptions, risks and uncertainties, including those described under the “Risk Factors” heading in this prospectus supplement and the accompanying base prospectus, as well as of our most recent Annual Report on Form10-K and, to the extent applicable, our Quarterly Reports on Form10-Q and Current Reports on Form8-K.

Many of these factors are beyond our ability to control or predict. Any of the factors, or a combination of these factors, could materially affect our future results of operations and the ultimate accuracy of the forward-looking statements. These forward-looking statements are not guarantees of our future performance, and our actual results and future developments may differ materially from those projected in the forward-looking statements. Management cautions against putting undue reliance on forward-looking statements or projecting any future results based on such statements or present or prior earnings levels. Forward-looking statements speak only as of the date of this prospectus supplement or, in the case of forward-looking statements contained in any document incorporated by reference, the date of such document, and we expressly disclaim any obligation or undertaking to update these statements after the date they are made to reflect any change in our expectations or beliefs, any change in events, conditions or circumstances on which any forward-looking statement is based, or otherwise. All forward-looking statements included this prospectus supplement, the accompanying base prospectus and the documents we incorporate by reference herein and therein are expressly qualified in their entirety by these cautionary statements.

S-28

Where You Can Find More Information

We file annual, quarterly and current reports and other information with the SEC. You may read and copy any materials we file at the SEC’s public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at1-800-732-0330 for further information on the public reference room. Our filings with the SEC are also available at the SEC’s website athttp://www.sec.gov, which contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. You can also obtain information about us at the offices of the NYSE, 20 Broad Street, New York, New York 10005, or on our website at http://www.wlkpartners.com. Information on our website or any other website is not incorporated by reference into this prospectus and does not constitute a part of this prospectus unless specifically so designated and filed with the SEC.

We “incorporate by reference” information into this prospectus, which means that we can disclose important information to you by referring you to other documents filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, except for any information superseded by information contained expressly in this prospectus, and the information that we file later with the SEC will automatically supersede this information. You should not assume that the information in this prospectus is current as of any date other than the date on the front page of this prospectus.

We incorporate by reference in this prospectus supplement the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (excluding information deemed to be furnished and not filed with the SEC), until all the common units offered hereby are sold:

our Annual Report on Form10-K for the fiscal year ended December 31, 2017;

our Quarterly Reports on Form10-Q for the quarterly periods ended March 31, 2018 and June 30, 2018;

our Current Reports on Form8-K filed on July 30, 2018 and October 4, 2018; and

the description of our common units in our Registration Statement on Form8-A (RegistrationNo. 001-36567) filed on July 24, 2014.

You may obtain any of the documents incorporated by reference into this prospectus from the SEC through the SEC’s website at the address provided above. You may request a copy of any document incorporated by reference in this prospectus and any exhibit specifically incorporated by reference in those documents, at no cost, by writing or telephoning us at the following address or phone number:

Westlake Chemical Partners LP

2801 Post Oak Boulevard, Suite 600

Houston, Texas 77056

(713)585-2900

S-29

PROSPECTUS

LOGO

Westlake Chemical Partners LP

Common Units Representing Limited Partner Interests

Other Classes of Units Representing Limited Partner Interests

WLKP Finance Corp.

Debt Securities

We may from time to time, in one or more offerings, offer and sell (i) common units representing limited partner interests in Westlake Chemical Partners LP (“common units”)., (ii) other classes of units representing limited partner interests in Westlake Chemical Partners LP (“other units”) and (iii) debt securities as described in this prospectus (“debt securities”). The debt securities will be issued by Westlake Chemical Partners LP. WLKP Finance Corp. may act asco-issuer of the debt securities. We refer to the common units, the debt securities and the other units collectively as the “securities.” The aggregate initial offering price of the securities sold by us under this prospectus will not exceed $500,000,000.

We may offer and sell the securities to or through one or more underwriters, dealers or agents, or directly to investors, in amounts, at prices and on terms to be determined by market conditions and other factors at the time of the offering. This prospectus describes only the general terms of the securities and the general manner in which we will offer the securities. The specific terms of any securities we offer will, if not included in this prospectus or information incorporated by reference herein, be included in a supplement to this prospectus. The prospectus supplement may describe the specific manner in which we will offer the securities and also may add, update or change information contained in this prospectus.

You should read this prospectus and any applicable prospectus supplement and the documents incorporated by reference herein or therein carefully before you invest in any of our securities. You should also read the documents we have referred you to in the “Where You Can Find More Information” section of this prospectus for information about us, including our financial statements. This prospectus may not be used to consummate sales of our securities unless it is accompanied by a prospectus supplement.

Our common units are listed on the New York Stock Exchange (the “NYSE”) under the symbol “WLKP.” The last reported sales price of our common units on the NYSE on March 9, 2017 was $25.25 per unit. We will provide information in the related prospectus supplement for the trading market, if any, for any other securities that may be offered.

Investing in our securities involves a high degree of risk. You should carefully consider the risks relating to investing in our securities and each of the other risk factors described under “Risk Factors” on page 2 of this prospectus before you make an investment in our securities.

Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of the securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is March 24, 2017.

TABLE OF CONTENTS


About This Prospectus			ii
Where You Can Find More Information			iii
Cautionary Statement Regarding Forward-Looking Statements			iv
Who We Are			1
Risk Factors			2
Ratio of Earnings to Combined Fixed Charges			3
Use of Proceeds			4
Description of Common Units and Preferred Units			5
Description of Partnership Securities			6
Description of Debt Securities			7
Material U.S. Federal Income Tax Consequences			15
Material U.S. Tax Consequences of Ownership of Debt Securities			30
Certain Erisa Considerations			31
Plan of Distribution			34
Legal Matters			36
Experts			36

In making your investment decision, you should rely only on the information contained in this prospectus, any prospectus supplement and the documents we have incorporated by reference in this prospectus. We have not authorized anyone else to give you different information. We are not offering the securities in any state where the offer is not permitted. You should not assume that the information in this prospectus or any prospectus supplement is accurate as of any date other than the date on the front of such documents. We will disclose any material changes in our affairs in an amendment to this prospectus, a prospectus supplement or a future filing with the SEC incorporated by reference in this prospectus.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we have filed with the SEC using a “shelf” registration process. Under this shelf registration process, we may over time, in one or more offerings, offer and sell up to $500,000,000 in total aggregate offering price of any combination of the securities described in this prospectus. This prospectus provides you with a general description of Westlake Chemical Partners LP and the securities that are registered hereunder and may be offered under this prospectus Each time we sell any securities offered by this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering and the securities being offered. A prospectus supplement may also add to, update or change information in this prospectus. Before you invest in our securities, you should carefully read this prospectus, any prospectus supplement, the additional information described under “Where You Can Find More Information,” and any additional information that you may need to make your investment decision.

To the extent information in this prospectus is inconsistent with the information contained in a prospectus supplement, you should rely on the information in the prospectus supplement. The information in this prospectus is accurate as of its date. Additional information, including our financial statements and the notes thereto, is incorporated in this prospectus by reference to our reports filed with the SEC and is accurate as of the date stated in such report.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and other reports and other information with the SEC. You may read and copy any materials we file at the SEC’s public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at1-800-732-0330 for further information on the public reference room. Our filings with the SEC are also available at the SEC’s website athttp://www.sec.gov, which contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. You can also obtain information about us at the offices of the New York Stock Exchange, 20 Broad Street, New York, New York 10005, or on our website athttp://www.wlkpartners.com. Information on our website or any other website is not incorporated by reference into this prospectus and does not constitute a part of this prospectus unless specifically so designated and filed with the SEC.

We “incorporate by reference” information into this prospectus, which means that we disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, except for any information superseded by information contained expressly in this prospectus, and the information that we file later with the SEC will automatically supersede this information. You should not assume that the information in this prospectus is current as of any date other than the date on the front page of this prospectus.

We incorporate by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) (excluding any information furnished and not filed with the SEC), including all such documents that we may file with the SEC after the date on which the registration statement that includes this prospectus was initially filed with the SEC and prior to the effectiveness of this registration statement, are incorporated by reference in this prospectus until the termination of all offerings under this registration statement:

•

Annual Report on Form10-K for the year ended December 31, 2016 filed on March 7, 2017; and

•

the description of our common units in our Registration Statement on Form8-A (RegistrationNo. 001-36567) filed on July 24, 2014.

You may request a copy of any document incorporated by reference to this prospectus, at no cost, by writing or calling us at the following:

Westlake Chemical Partners LP

2801 Post Oak Boulevard, Suite 600

Houston, Texas 77056

(713) 585-2900

You should rely only on the information contained in, or incorporated by reference into, this prospectus or any prospectus supplement. We have not authorized anyone else to provide you with any information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information incorporated by reference or provided in this prospectus or any prospectus supplement is accurate as of any date other than its respective date.

iii

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

Certain of the statements included in or incorporated by reference into this prospectus or any accompanying prospectus supplement are forward-looking statements. All such statements, other than statements of historical facts, that address activities, events or developments that we expect, project, believe or anticipate will or may occur in the future are forward-looking statements, including, without limitation, statements regarding our plans, strategies, prospects and expectations concerning our business, results of operations and financial conditions. Forward-looking statements can be identified by the use of words such as “believes,” “intends,” “may,” “should,” “could,” “anticipates,” “expects,” “will” or comparable terminology, or by discussions of strategies or trends. These forward-looking statements are based on our current expectations and beliefs concerning future developments and their potential effect on us. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give any assurances that these expectations will prove to be correct. All comments concerning our expectations for future revenues and operating results are based on our forecasts for our existing operations and do not include the potential impact of any future acquisitions. Our forward-looking statements involve significant risks and uncertainties (some of which are beyond our control) and assumptions that could cause actual results to differ materially from our historical experience and our present expectations or projections. Known material factors that could cause our actual results to differ from those in these forward-looking statements are described below and in “Risk Factors” in this prospectus or any prospectus supplement. Forward-looking statements relate to matters such as:

•

the amount of ethane that we are able to process, which could be adversely affected by, among other things, operating difficulties;

•

the volume of ethylene that we are able to sell;

•

the price at which we are able to sell ethylene;

•

industry market outlook, including prices and margins in third-party ethylene andco-products sales;

•

the parties to whom we will sell ethylene and on what basis;

•

volumes of ethylene that Westlake (as defined below) may purchase, in addition to the minimum commitment under our Ethylene Sales Agreement with Westlake;

•

timing, funding and results of capital projects, such as OpCo’s (as defined below) plan to increase the ethylene capacity of the ethylene processing facility at Calvert City Olefins (as defined below);

•

our intended minimum quarterly distributions and the manner of making such distributions;

•

our ability to meet our liquidity needs;

•

timing and amount of capital expenditures;

•

potential loans from Westlake to OpCo to fund OpCo’s expansion capital expenditures in the future;

•

expected mitigation of exposure to commodity price fluctuations;

•

turnaround activities and the variability of OpCo’s cash flow;

•

effects of pending legal proceedings; and

•

other factors discussed below, in “Risk Factors” and in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” included in our most recent annual report onForm 10-K and our quarterly reports on Form10-Q that are incorporated by reference herein, in our current reports on Form8-K that are incorporated by reference herein, and elsewhere in our other public filings and press releases.

Many of these factors are beyond our ability to control or predict. Any of the factors, or a combination of these factors, could materially affect our future results of operations and the ultimate accuracy of the forward-looking statements. These forward-looking statements are not guarantees of our future performance, and our actual results and future developments may differ materially from those projected in the forward-looking statements. Management cautions against putting undue reliance on forward-looking statements or projecting any future results based on such statements or present or prior earnings levels. Forward-looking statements speak only as of the date of this prospectus or, in the case of forward-looking statements contained in any document incorporated by reference, the date of such document, and we expressly disclaim any obligation or undertaking to update these statements after the date they are made to reflect any change in our expectations or beliefs, any change in events, conditions or circumstances on which any forward-looking statement is based or otherwise. All forward-looking statements included in this prospectus, any prospectus supplement and the documents we incorporate by reference herein and therein are expressly qualified in their entirety by these cautionary statements.

WHO WE ARE

Unlessthecontextotherwiserequires,referencesinthisprospectustothe“Partnership,”“we”“our,”“us”orliketermsreferto“WestlakeChemicalPartnersLP”and,unlessotherwisespecified,WestlakeChemicalOpCoLPandWestlakeChemicalOpCoGPLLC.Referencesinthisprospectustoour“generalpartner”refertoWestlakeChemicalPartnersGPLLC.Referencesto“OpCo”refertoWestlakeChemicalOpCoLPanditssubsidiaries.Referencesto“Westlake”refercollectivelytoWestlakeChemicalCorporationanditssubsidiaries,otherthanus,ourgeneralpartner,OpCoanditssubsidiaries,andWestlakeChemicalOpCoGPLLC,OpCo’sgeneralpartner.

Overview

We are a Delaware limited partnership formed by Westlake to operate, acquire and develop ethylene production facilities and related assets. Currently, our sole revenue generating asset is our 13.3% limited partner interest in OpCo, a limited partnership formed by Westlake and us in anticipation of our initial public offering in August 2014 to own and operate a natural gas liquids processing business. We control OpCo through our ownership of its general partner. Westlake owns the remaining 86.7% limited partner interest in OpCo as well as significant interests in us through its ownership of our general partner, 52.2% of our limited partner units (consisting of 1,436,115 common units and all of the subordinated units) and our incentive distribution rights. OpCo’s assets include (1) two natural gas liquids processing facilities at Westlake’s Lake Charles, Louisiana site, (2) one natural gas liquids processing facility at Westlake’s Calvert City, Kentucky site (“Calvert City Olefins”); and (3) a200-mile common carrier ethylene pipeline that runs from Mont Belvieu, Texas to Westlake’s Longview, Texas facility.

Our principal executive offices are located at 2801 Post Oak Boulevard, Suite 600, Houston, Texas 77056, and our telephone number is (713) 585-2900.

RISK FACTORS

An investment in our securities involves a significant degree of risk. Before you invest in our common units you should carefully consider the risk factors and all of the other information included in this prospectus and any prospectus supplement, and the documents we have incorporated by reference, including those in our most recent Annual Report on Form10-K as updated by our quarterly and other reports and documents we file with the SEC after the date of this prospectus, in evaluating an investment in the securities. If any of these risks were actually to occur, our business, financial condition or results of operations could be materially adversely affected. In that case, our ability to make distributions to our unitholders or pay interest on, or the principal of, any debt securities, may be reduced. When we offer and sell any securities pursuant to a prospectus supplement, we may include additional risk factors relevant to such securities in the prospectus supplement. Also, please read “Cautionary Statement Regarding Forward-Looking Statements.”

RATIO OF EARNINGS TO COMBINED FIXED CHARGES

The table below sets forth our ratio of earnings to fixed charges and preference dividends for the periods presented. During the periods presented, we had no preference equity securities outstanding. Therefore, for each period, the ratio of earnings to fixed charges and the ratio of earnings to combined fixed charges and preference dividends is the same.

Year Ended December 31,

2016

2015

2014(1)

2013(1)

2012(1)

Ratio of earnings to fixed charges

19.0x

32.4x

50.4x

91.7x

62.1x

(1)

During the years ended December 31, 2012 and 2013 and the period from January 1, 2014 through August 4, 2014 (the closing date of our initial public offering), our ratio of earnings to fixed charges was calculated based on our predecessor for accounting purposes, which reflects Westlake’s entire ethylene business.

For purposes of calculating the ratio of consolidated earnings to fixed charges:

“earnings” is the aggregate of the following items:pre-tax income from continuing operations before adjustment for income or loss from equity investees;plus fixed charges;plus amortization of capitalized interest;plus distributed income of equity method investees; andless capitalized interest; and

“fixed charges” means the sum of the following: interest expensed and capitalized; amortized premiums, discounts and capitalized expenses related to indebtedness; and an estimate of the interest within rental expense. Fixed charges are not reduced by any allowance for funds used during construction.

USE OF PROCEEDS

Unless otherwise indicated in the applicable prospectus supplement, we intend to use the net proceeds we receive from the sale of the securities offered by this prospectus and any prospectus supplement for general partnership purposes, which may include repayment of indebtedness, the financing of capital expenditures, future acquisitions and additions to our working capital.

Any specific allocation of the net proceeds of an offering of securities to a specific purpose will be determined at the time of the offering and will be described in the applicable prospectus supplement.

DESCRIPTION OF COMMON UNITS AND PREFERRED UNITS

Common Units

Please see our registration statement on Form8-A (FileNo. 001-36567) filed on July 24, 2014 (together with any amendments thereto and the other documents incorporated by reference therein), which is incorporated by reference herein, for a description of our common units, our cash distribution policy and our partnership agreement.

Preferred Units

Our partnership agreement authorizes us to issue an unlimited number of additional limited partner interests and other equity securities for the consideration and with the designations, preferences, rights, powers and duties established by our general partner without the approval of any of our limited partners. In accordance with Delaware law and the provisions of our partnership agreement, we may issue additional partnership interests that have special voting rights to which our common units or subordinated units are not entitled. As of the date of this prospectus, we have no preferred units outstanding.

Should we offer preferred units under this prospectus, a prospectus supplement relating to the particular series of preferred units offered will include the specific terms of those preferred units, including, among other things, the following:

•

the designation, stated value and liquidation preference of the preferred units and the number of preferred units offered;

•

the price at which the preferred units will be issued;

•

the conversion or exchange provisions of the preferred units;

•

any redemption or sinking fund provisions of the preferred units;

•

the distribution rights of the preferred units, if any;

•

a discussion of any additional material federal income tax considerations regarding the preferred units; and

•

any additional rights, preferences, privileges, limitations and restrictions of the preferred units.

DESCRIPTION OF PARTNERSHIP SECURITIES

Our partnership agreement authorizes us to issue an unlimited number of additional limited partner interests and other equity securities for the consideration and on the terms and conditions established by our general partner without the approval of any limited partners.

In accordance with Delaware law and the provisions of our partnership agreement, we also may issue additional partnership interests that, if approved by our general partner, have special voting rights to which the common units are not entitled.

The following is a description of the general terms and provisions of our partnership securities. The particular terms of any series of partnership securities will be described in the applicable prospectus supplement and the amendment to our partnership agreement, if necessary, relating to that series of partnership securities, which will be filed as an exhibit to or incorporated by reference into this prospectus at or before the time of issuance of any such series of partnership securities. If so indicated in a prospectus supplement, the terms of any such series may differ from the terms set forth below.

Our general partner is authorized to approve the issuance of one or more series of partnership securities without further authorization of the limited partners and to fix the number of securities, the designations, rights, privileges, restrictions and conditions of any such series.

The applicable prospectus supplement will set forth the number of securities, particular designation, relative rights and preferences and the limitations of any series of partnership securities in respect of which this prospectus is delivered. The particular terms of any such series may include the following:

•

the maximum number, if any, of securities to constitute the series and the designation and ranking thereof;

•

the distribution rate, if any, on securities of the series, whether such rate is fixed or variable or both, the dates from which distributions will begin to accrue or accumulate, whether distributions will be cumulative and whether such distributions will be paid in cash, securities or otherwise;

•

whether the securities of the series will be redeemable and, if so, the price and the terms and conditions on which the securities of the series may be redeemed, including the time during which securities of the series may be redeemed and any accumulated distributions thereof that the holders of the securities of the series will be entitled to receive upon the redemption thereof;

•

the liquidation preference, if any, applicable to securities of the series;

•

the terms and conditions, if any, on which the securities of the series will be convertible into, or exchangeable for, securities of any other class or classes of partnership securities, including the price or prices or the rate or rates of conversion or exchange and the method, is any, of adjusting the same; and

•

the voting rights, if any, of the securities of the series.

Partnership securities will be fully paid and, except as provided under Delaware Law,non-assessable when issued upon full payment of the purchase price therefor. The prospectus supplement will contain, if applicable, a description of the material United States federal income tax consequences relating to the purchase and ownership of the series of partnership securities offered thereby. The transfer agent, registrar and distributions disbursement agent for the partnership securities will be designated in the applicable prospectus supplement.

DESCRIPTION OF DEBT SECURITIES

General

Westlake Chemical Partners LP may issue senior and unsubordinated debt securities in one or more series, and WLKP Finance Corp. may be aco-issuer of one or more series of debt securities. WLKP Finance Corp. is 100% owned by Westlake Chemical Partners LP, and has no assets or current operations and has been formed for the sole purpose of acting asco-issuer of debt securities, and therefore falls within the meaning of a “minor” subsidiary under Rule3-10(h) of RegulationS-X. Its activities are limited toco-issuing debt securities and engaging in other activities incidental thereto. Any debt securitiesco-issued by Westlake Chemical Partners LP and WLKP Finance Corp. will be issued jointly and severally. When used in this section “Description of Debt Securities,” the terms “we,” “us,” “our” and “issuers” refer jointly to Westlake Chemical Partners LP and WLKP Finance Corp. if the latter is aco-issuer of the series of debt securities and otherwise only to the former, and the terms “WLKP” and “WLKP Finance” refer strictly to Westlake Chemical Partners LP and WLKP Finance Corp., respectively.

If we offer debt securities, we will issue them in one or more series under an indenture among each issuer, any guarantors and a trustee (the “Trustee”). A form of the indenture is filed as an exhibit to the registration statement of which this prospectus is a part. We have not restated the indenture in its entirety in this description. You should read the relevant indenture because it, and not this description, controls your rights as holders of the debt securities. Capitalized terms used in the summary have the meanings specified in the indenture.

Specific Terms of Each Series of Debt Securities in the Prospectus Supplement

A prospectus supplement and a supplemental indenture or authorizing resolutions relating to any series of debt securities being offered will include specific terms relating to the offering. These terms will include some or all of the following:

•

whether WLKP Finance will be aco-issuer;

•

the guarantors of the debt securities, if any;

•

the title of the debt securities;

•

the total principal amount of the debt securities;

•

the assets, if any, that are pledged as security for the payment of the debt securities;

•

whether we will issue the debt securities in individual certificates to each holder in registered form, or in the form of temporary or permanent global securities held by a depository on behalf of holders;

•

the prices at which we will issue the debt securities;

•

the portion of the principal amount that will be payable if the maturity of the debt securities is accelerated;

•

the currency or currency unit in which the debt securities will be payable, if not U.S. dollars;

•

the dates on which the principal of the debt securities will be payable;

•

the interest rate that the debt securities will bear and the interest payment dates for the debt securities;

•

any conversion or exchange provisions;

•

any optional redemption provisions;

•

any sinking fund or other provisions that would obligate us to repurchase or redeem the debt securities;

•

any changes to or additional events of default or covenants; and

•

any other terms of the debt securities.

We may offer and sell debt securities, including original issue discount debt securities, at a substantial discount below their principal amount. The prospectus supplement will describe special U.S. federal income tax and any other considerations applicable to those securities. In addition, the prospectus supplement may describe certain special U.S. federal income tax or other considerations applicable to any debt securities that are denominated in a currency other than U.S. dollars.

Possible Future Guarantors

We contemplate that none of the subsidiaries of WLKP will guarantee the debt securities of any series. If at any time after the issuance of the debt securities of any series, however, a subsidiary of WLKP guarantees any of our debt, we will cause such subsidiary to guarantee that series in accordance with the indenture by simultaneously executing and delivering a supplemental indenture.

Any guarantors of a series of debt securities would unconditionally guarantee to each holder and the Trustee, on a joint and several basis, the full and prompt payment of the principal of, premium, if any, and interest on the debt securities of that series when and as the same became due and payable, whether at stated maturity, upon redemption or repurchase, by declaration of acceleration or otherwise. If a series of debt securities is guaranteed, the related prospectus supplement will identify all of the guarantor subsidiaries. Also, such prospectus supplement will describe any limitation on the maximum amount of any particular guarantee and the conditions under which guarantees may be released.

Any guarantees would be general, senior and unsubordinated obligations of the guarantors.

Consolidation, Merger or Asset Sale

The indenture will, in general, allow us to consolidate or merge with or into another domestic entity. It will also allow each issuer to sell, lease, transfer or otherwise dispose of all or substantially all of its assets to another domestic entity. If this happens, the remaining or acquiring entity must assume all of the issuer’s responsibilities and liabilities under the indenture including the payment of all amounts due on the debt securities and performance of the issuer’s covenants in the indenture.

However, the indenture will impose certain requirements with respect to any consolidation or merger with or into an entity, or any sale, lease, transfer or other disposition of all or substantially all of an issuer’s assets, including:

•

the remaining or acquiring entity must be organized under the laws of the United States, any state or the District of Columbia;

•

the remaining or acquiring entity must assume the issuer’s obligations under the indenture; and

•

immediately after giving effect to the transaction, no Default or Event of Default (as defined under “—Events of Default and Remedies”) may exist.

The remaining or acquiring entity will be substituted for the issuer in the indenture with the same effect as if it had been an original party to the indenture, and the issuer will be relieved from any further obligations under the indenture, except in the case of a lease of all or substantially all of its assets.

No Protection in the Event of a Change of Control

Unless otherwise set forth in the prospectus supplement, the debt securities will not contain any provisions that protect the holders of the debt securities in the event of a change of control of us or in the event of a highly leveraged transaction, whether or not such transaction results in a change of control of us.

Modification of Indenture

We may supplement or amend the indenture if the holders of a majority in aggregate principal amount of the outstanding debt securities of each series affected by the supplement or amendment consent to it. Further, the holders of a majority in aggregate principal amount of the outstanding debt securities of any series may waive past defaults under the indenture and compliance by us with our covenants with respect to the debt securities of that series only. However, without the consent of each outstanding debt security affected, no modification of the indenture or waiver may:

•

reduce the principal of or extend the fixed maturity of any debt security;

•

reduce any premium payable upon redemption or change any redemption date with respect to the redemption of the debt securities;

•

reduce the rate of or extend the time for payment of interest on any debt security;

•

waive a past Default or an Event of Default in the payment of principal of or premium, if any, or interest on the debt securities or in respect of an indenture provision that cannot be modified without the consent of each affected holder;

•

except as otherwise permitted under the indenture, release any security that may have been granted with respect to the debt securities;

•

make any debt security payable in currency other than that stated in the debt securities;

•

impair the right of any holder to receive any payment on its debt securities on or after the due date therefor or to institute suit for the enforcement of any such payment;

•

waive any redemption payment with respect to any debt security (except as may be permitted in the case of a particular series of debt securities);

•

except as otherwise permitted in the indenture, release any guarantor from its obligations under its guarantee or the indenture or change any guarantee in any manner adverse to the holders; or

•

make any change in the preceding amendment, supplement and waiver provisions (except to increase any percentage set forth therein).

We may supplement or amend the indenture without the consent of any holders of the debt securities in certain circumstances, including:

•

to establish the form of terms of any series of debt securities;

•

to cure any ambiguity, defect or inconsistency;

•

to provide for uncertificated notes in addition to or in place of certificated notes;

•

to provide for the assumption of an issuer’s obligations to holders of debt securities in the case of a merger or consolidation or disposition of all or substantially all of such issuer’s assets;

•

to add or release guarantors pursuant to the terms of the indenture;

•

to make any change that does not adversely affect the rights under the indenture of any holder of debt securities;

•

to comply with requirements of the SEC in order to effect or maintain the qualification of the indenture under the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”);

•

to evidence or provide for the acceptance of appointment under the indenture of a successor Trustee;

•

to add any additional Events of Default (as defined below) with respect to any series of debt securities; or

•

to secure the debt securities or any guarantees.

Events of Default, Remedies and Notice

“EventofDefault,” when used in the indenture, will mean any of the following with respect to the debt securities of any series:

•

failure to pay when due the principal of or any premium on any debt security of that series;

•

failure to pay, within 60 days of the due date, interest on any debt security of that series;

•

failure to pay when due any sinking fund payment with respect to any debt securities of that series;

•

failure on the part of an issuer to comply with the covenant described under “—Consolidation, Merger or Asset Sale”;

•

failure to perform any other covenant in the indenture that continues for 30 days after written notice is given to the issuers;

•

certain events of bankruptcy, insolvency or reorganization of an issuer or any guarantor of that series;

•

if the debt securities of that series are entitled to a guarantee, the guarantee ceases to be in full force and effect; or

•

any other Event of Default provided under the terms of the debt securities of that series.

An Event of Default for a particular series of debt securities will not necessarily constitute an Event of Default for any other series of debt securities issued under the indenture. The Trustee may withhold notice to the holders of debt securities of any default (except in the payment of principal, premium, if any, or interest) if it considers such withholding of notice to be in the best interests of the holders.

If an Event of Default for any series of debt securities occurs and continues, the Trustee or the holders of at least 25% in aggregate principal amount of the debt securities of the series may declare the entire principal of, and accrued interest on, all the debt securities of that series to be due and payable immediately. If this happens, subject to certain conditions, the holders of a majority in the aggregate principal amount of the debt securities of that series can rescind the declaration.

Other than its duties in case of a default, a Trustee is not obligated to exercise any of its rights or powers under either indenture at the request, order or direction of any holders, unless the holders offer the Trustee reasonable security or indemnity. If they provide this reasonable security or indemnification, the holders of a majority in aggregate principal amount of any series of debt securities may direct the time, method and place of conducting any proceeding or any remedy available to the Trustee, or exercising any power conferred upon the Trustee, for that series of debt securities.

No Limit on Amount of Debt Securities

The indenture will not limit the amount of debt securities that we may issue, unless we indicate otherwise in a prospectus supplement. The indenture will allow us to issue debt securities of any series up to the aggregate principal amount that we authorize.

Registration of Notes

We will issue debt securities of a series only in registered form, without coupons.

Minimum Denominations

Unless the prospectus supplement states otherwise, the debt securities will be issued only in principal amounts of $1,000 each or integral multiples of $1,000.

No Personal Liability

None of the past, present or future partners, incorporators, managers, members, directors, officers, employees, unitholders or stockholders of either issuer, the general partner of WLKP or any guarantor, as such, will have any liability for the obligations of the issuers or any guarantor under the indenture or the debt securities or for any claim based on such obligations or their creation. Each holder of debt securities by accepting a debt security waives and releases all such liability. The waiver and release are part of the consideration for the issuance of the debt securities. The waiver may not be effective under federal securities laws, however, and it is the view of the SEC that such a waiver is against public policy.

Payment and Transfer

The Trustee will initially act as paying agent and registrar under the indenture. The issuers may change the paying agent or registrar without prior notice to the holders of debt securities, and the issuers or any of their subsidiaries may act as paying agent or registrar.

If a holder of debt securities has given wire transfer instructions to the issuers, the issuers will make all payments on the debt securities in accordance with those instructions. All other payments on any debt securities not in a global form will be made at the corporate trust office of the Trustee, unless the issuers elect to make interest payments by check mailed to the holders at their addresses set forth in the debt security register.

The Trustee and any paying agent will repay to us upon request any funds held by them for payments on the debt securities that remain unclaimed for two years after the date upon which that payment has become due. After payment to us, holders entitled to the money must look to us for payment as general creditors.

Exchange, Registration and Transfer

Debt securities of any series will be exchangeable for other debt securities of the same series, the same total principal amount and the same terms but in different authorized denominations in accordance with the indenture. Holders may present debt securities for exchange or registration of transfer at the office of the registrar. The registrar will effect the transfer or exchange when it is satisfied with the documents of title and identity of the person making the request. We will not charge a service charge for any registration of transfer or exchange of the debt securities. We may, however, require the payment of any tax or other governmental charge payable for that registration.

We will not be required:

•

to issue, register the transfer of, or exchange debt securities of a series either during a period of 15 days prior to the mailing of a notice of redemption of debt securities of that series; or

•

to register the transfer of or exchange any debt security called for redemption, except the unredeemed portion of any debt security we are redeeming in part.

Ranking

The debt securities will rank equally in right of payment with all of our other senior and unsubordinated debt. The debt securities will be effectively subordinated, however, to all of our secured debt to the extent of the value of the collateral for that debt. We will disclose the amount of our secured debt in the prospectus supplement.

Book Entry, Delivery and Form

The debt securities of a particular series may be issued in whole or in part in the form of one or more global certificates that will be deposited with the Trustee as custodian for The Depository Trust Company, New York,

New York (“DTC”) and registered in the name of DTC’s nominee, Cede & Co. This means that we will not issue certificates to each holder. Instead, one or more global debt securities will be issued to DTC, who will keep a computerized record of its participants (for example, your broker) whose clients have purchased the debt securities. The participant will then keep a record of its clients who purchased the debt securities. Unless it is exchanged in whole or in part for a certificated debt security, a global debt security may not be transferred, except that DTC, its nominees and their successors may transfer a global debt security as a whole to one another.

Beneficial interests in global debt securities will be shown on, and transfers of beneficial interests in global debt securities will be made only through, records maintained by DTC and its participants.

DTC has provided us the following information: DTC is a limited-purpose trust company organized under the New York Banking Law, a “banking organization” within the meaning of the New York Banking Law, a member of the United States Federal Reserve System, a “clearing corporation” within the meaning of the New York Uniform Commercial Code and a “clearing agency” registered under the provisions of Section 17A of the Securities Exchange Act of 1934, as amended. DTC holds securities that its participants (“Direct Participants”) deposit with DTC. DTC also records the settlement among Direct Participants of securities transactions, such as transfers and pledges, in deposited securities through computerized records for Direct Participants’ accounts. This eliminates the need to exchange certificates. Direct Participants include securities brokers and dealers, banks, trust companies, clearing corporations and certain other organizations.

DTC’s book-entry system is also used by other organizations such as securities brokers and dealers, banks and trust companies that work through a Direct Participant. The rules that apply to DTC and its Direct Participants are on file with the SEC.

DTC is a wholly-owned subsidiary of The Depository Trust & Clearing Corporation (“DTCC”). DTCC, in turn, is owned by a number of its participants and by, among other institutions, the Financial Industry Regulatory Authority, Inc. The rules that apply to DTC and its participants are on file with the SEC.

We will wire all payments on the global debt securities to DTC’s nominee. We and the Trustee will treat DTC’s nominee as the owner of the global debt securities for all purposes. Accordingly, we, the Trustee and any paying agent will have no direct responsibility or liability to pay amounts due on the global debt securities to owners of beneficial interests in the global debt securities

It is DTC’s current practice, upon receipt of any payment on the global debt securities, to credit Direct Participants’ accounts on the payment date according to their respective holdings of beneficial interests in the global debt securities as shown on DTC’s records. In addition, it is DTC’s current practice to assign any consenting or voting rights to Direct Participants whose accounts are credited with debt securities on a record date, by using an omnibus proxy. Payments by Direct Participants to owners of beneficial interests in the global debt securities, and voting by Direct Participants, will be governed by the customary practices between the Direct Participants and owners of beneficial interests, as is the case with debt securities held for the account of customers registered in “street name.” However, payments will be the responsibility of the Direct Participants and not of DTC, the Trustee or us.

Debt securities represented by a global debt security will be exchangeable for certificated debt securities with the same terms in authorized denominations only if:

•

DTC notifies us that it is unwilling or unable to continue as depositary or if DTC ceases to be a clearing agency registered under applicable law and in either event a successor depositary is not appointed by us within 90 days; or

•

following an Event of Default, DTC notifies the Trustee of its decision to require that the debt securities of a series shall no longer be represented by a global debt security.

Satisfaction and Discharge; Defeasance

The indenture will be discharged and will cease to be of further effect as to all outstanding debt securities of any series issued thereunder, when:

(a)

either:

(1)

all outstanding debt securities of that series that have been authenticated (except lost, stolen or destroyed debt securities that have been replaced or paid and debt securities for whose payment money has theretofore been deposited in trust and thereafter repaid to us) have been delivered to the Trustee for cancellation; or

(2)

all outstanding debt securities of that series that have not been delivered to the Trustee for cancellation have become due and payable by reason of the giving of a notice of redemption or otherwise or will become due and payable at their stated maturity within one year or are to be called for redemption within one year under arrangements satisfactory to the Trustee and in any case we have irrevocably deposited with the Trustee as trust funds in trust cash sufficient, without consideration of any reinvestment of interest, to pay and discharge the entire indebtedness of such debt securities not delivered to the Trustee for cancellation, for principal, premium, if any, and accrued interest to the date of such deposit (in the case of debt securities that have been due and payable) or the stated maturity or redemption date; and

(b)

we have paid or caused to be paid all other sums payable by us under the indenture.

The debt securities of a particular series will be subject to legal or covenant defeasance to the extent, and upon the terms and conditions, set forth in the prospectus supplement.

Governing Law

The indenture and all of the debt securities will be governed by the laws of the State of New York.

The Trustee

We will enter into the indenture with a Trustee that is qualified to act under the Trust Indenture Act, and with any other Trustees chosen by us and appointed in a supplemental indenture for a particular series of debt securities. We will identify in the applicable prospectus supplement, the Trustee for each series of debt securities and will file an application with the SEC under the Trust Indenture Act to qualify the Trustee.

Resignation or Removal of Trustee

If the Trustee has or acquires a conflicting interest within the meaning of the Trust Indenture Act, the Trustee must either eliminate its conflicting interest or resign, to the extent and in the manner provided by, and subject to the provisions of, the Trust Indenture Act and the indenture. Any resignation will require the appointment of a successor Trustee in accordance with the terms and conditions of the indenture.

The Trustee may resign or be removed by us with respect to one or more series of debt securities and a successor Trustee may be appointed to act with respect to any such series. The holders of a majority in aggregate principal amount of the debt securities of any series may remove the Trustee with respect to the debt securities of such series.

Limitations on Trustee if it is Our Creditor

The indenture will contain certain limitations on the right of the Trustee, in the event that it becomes a creditor of an issuer, to obtain payment of claims in certain cases, or to realize on certain property received in respect of any such claim as security or otherwise.

Annual Trustee Report to Holders of Debt Securities

The Trustee will submit an annual report to the holders of the debt securities regarding, among other things, the Trustee’s eligibility to serve as such, the priority of the Trustee’s claims regarding certain advances made by it, and any action taken by the Trustee materially affecting the debt securities.

Certificates and Opinions to be Furnished to Trustee

The indenture will provide that, in addition to other certificates or opinions that may be specifically required by other provisions of the indenture, every application by us for action by the Trustee shall be accompanied by a certificate of certain of our officers and an opinion of counsel (who may be our counsel) stating that, in the opinion of the signers, all conditions precedent to such action have been complied with by us.

MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES

This section summarizes the material U.S. federal income tax consequences that may be relevant to prospective unitholders and is based upon current provisions of the Internal Revenue Code of 1986, as amended (the “Code”), existing and proposed Treasury regulations thereunder (the “Treasury Regulations”), and current administrative rulings and court decisions, all of which are subject to change. Changes in these authorities may cause the federal income tax consequences to a prospective unitholder to vary substantially from those described below, possibly on a retroactive basis. Unless the context otherwise requires, references in this section to “we” or “us” are references to Westlake Chemical Partners LP and its subsidiaries.

Legal conclusions contained in this section, unless otherwise noted, are the opinion of Vinson & Elkins L.L.P. and are based on the accuracy of representations made by us to them for this purpose. However, this section does not address local taxes, state taxes,non-U.S. taxes, other taxes or all federal income tax matters that affect us or our unitholders such as the application of the alternative minimum tax that may be applicable to certain unitholders. Furthermore, this section focuses on unitholders who are individual citizens or residents of the United States (for federal income tax purposes), who have the U.S. dollar as their functional currency, who use the calendar year as their taxable year, who purchase units in this offering, who do not materially participate in the conduct of our business activities and who hold such units as capital assets (typically, property that is held for investment). This section has limited applicability to corporations (including other entities treated as corporations for federal income tax purposes), partnerships (including other entities treated as partnerships for federal income tax purposes), estates, trusts,non-resident aliens or other unitholders subject to specialized tax treatment, such astax-exempt entities,non-U.S. persons, individual retirement accounts (“IRAs”), employee benefit plans, real estate investment trusts or mutual funds.Accordingly,weencourageeachprospectiveunitholdertoconsulttheunitholder’sowntaxadvisorinanalyzingthefederal,state,localandnon-U.S.taxconsequencesparticulartothatunitholderresultingfromownershipordispositionofunitsandpotentialchangesinapplicabletaxlaws.

We have requested and obtained a favorable private letter ruling from the IRS to the effect that the production, transportation, storage and marketing of ethylene and itsco-products will constitute “qualifying income” within the meaning of Section 7704 of the Code. However, no ruling has been or will be requested from the IRS regarding our treatment as a partnership for U.S. federal income tax purposes. Instead, we will rely on the opinions and advice of Vinson & Elkins L.L.P. with respect to the matters described herein. An opinion of counsel represents only that counsel’s best legal judgment and does not bind the Internal Revenue Service (the “IRS”) or a court. Accordingly, the opinions and statements made herein may not be sustained by a court if contested by the IRS. Any such contest of the matters described herein may materially and adversely impact the market for our units and the prices at which our units trade. In addition, our costs of any contest with the IRS will be borne indirectly by our unitholders and our general partner because the costs will reduce our cash available for distribution. Furthermore, the tax consequences of an investment in us may be significantly modified by future legislative or administrative changes or court decisions, which may be retroactively applied.

For the reasons described below, Vinson & Elkins L.L.P. has not rendered an opinion with respect to the following federal income tax issues:

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the treatment of a unitholder whose units are the subject of a securities loan (e.g., a loan to a short seller to cover a short sale of units) (please read “—Tax Consequences of Unit Ownership—Treatment of Securities Loans”);

•

whether our monthly convention for allocating taxable income and losses is permitted by existing Treasury Regulations (please read “—Disposition of Units—Allocations Between Transferors and Transferees”); and

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Taxation of the Partnership

Partnership Status

We expect to be treated as a partnership for U.S. federal income tax purposes and, therefore, subject to the discussion below under “—Administrative Matters—Information Returns and Audit Procedures”, generally will not be liable for entity-level federal income taxes. Instead, as described below, each of our unitholders will take into account its respective share of our items of income, gain, loss and deduction in computing its federal income tax liability as if the unitholder had earned such income directly, even if we make no cash distributions to the unitholder. Distributions we make to a unitholder will not give rise to income or gain taxable to such unitholder, unless the amount of cash distributed exceeds the unitholder’s adjusted tax basis in its units. Please read “—Tax Consequences of Unit Ownership—Treatment of Distributions” and “—Disposition of Units”).

Section 7704 of the Code provides that a publicly-traded partnership will be treated as a corporation for federal income tax purposes. However, if 90% or more of a partnership’s gross income for every taxable year it is publicly-traded consists of “qualifying income,” the partnership may continue to be treated as a partnership for federal income tax purposes (the “Qualifying Income Exception”). Qualifying income includes, (i) income and gains derived from the processing, transportation, storage and marketing of any mineral or natural resource (such as crude oil, refined products and NGLs), (ii) interest (other than from a financial business), (iii) dividends, (iv) gains from the sale of real property and (v) gains from the sale or other disposition of capital assets (or property described in Section 1231(b) of the Code) held for the production of income that otherwise constitutes qualifying income. We estimate that less than 5.0% of our current gross income is not qualifying income; however, this estimate could change from time to time.

Vinson & Elkins L.L.P. is of the opinion that we and our partnership and limited liability company subsidiaries will be disregarded as separate from us or treated as partnerships for federal income tax purposes. In rendering its opinion, Vinson & Elkins L.L.P. has relied on the factual representations made by us and our general partner, including, without limitation:

(a)

Neither we nor any of our partnership or limited liability company subsidiaries has elected or will elect to be treated as a corporation for federal income tax purposes;

(b)

For each taxable year since and including the year of our initial public offering, more than 90% of our gross income has been and will be income of a character that Vinson & Elkins L.L.P. has opined is “qualifying income” within the meaning of Section 7704(d) of the Code, including income earned pursuant to processes described in our private letter ruling; and

(c)

Each hedging transaction that we treat as resulting in qualifying income has been and will be appropriately identified as a hedging transaction pursuant to applicable Treasury Regulations, and has been and will be associated with oil, natural gas or products thereof that are held or to be held by us in activities that Vinson & Elkins L.L.P. has opined or will opine result in qualifying income.

We believe that these representations are true and will be true in the future.

to make adjustments with respect to our unitholders or pay other amounts), we will be treated as transferring all of our assets, subject to all of our liabilities, to a newly formed corporation, on the first day of the year in which we fail to meet the Qualifying Income Exception, in return for stock in that corporation and then as distributing that stock to our unitholders in liquidation. This deemed contribution and liquidation should not result in the recognition of taxable income by our unitholders or us so long as the aggregate amount of our liabilities does not exceed the adjusted tax basis of our assets. Thereafter, we would be treated as an association taxable as a corporation for federal income tax purposes.

The present federal income tax treatment of publicly traded partnerships, including us, or an investment in our units may be modified by administrative or legislative action or judicial interpretation at any time. For example, from time to time, members of the U.S. Congress propose and consider substantive changes to the existing federal income tax laws that affect publicly-traded partnerships. One such legislative proposal would have eliminated the Qualifying Income Exception upon which we rely for our treatment as a partnership for federal income tax purposes.

In addition, on January 24, 2017, final regulations regarding which activities give rise to qualifying income within the meaning of Section 7704 of the Code (the “Final Regulations”) were published in the Federal Register. The Final Regulations, consistent with our private letter ruling, treat our income from the production, transportation, storage and marketing of ethylene and itsco-products constitutes as “qualifying income”. However, there can be no assurance that there would not be further changes to the Treasury Department’s interpretation of the qualifying income rules in a manner that could impact our ability to qualify as a partnership in the future.

It is possible that a change in law could affect us and may be applied retroactively. Any such changes could negatively impact the value of an investment in our units. If for any reason we are taxable as a corporation in any taxable year, our items of income, gain, loss and deduction would be taken into account by us in determining the amount of our liability for federal income tax, rather than being passed through to our unitholders. Our partnership agreement provides that if a law is enacted or existing law is modified or interpreted in a manner that subjects us to taxation as a corporation or otherwise subjects us to entity-level taxation for federal, state or local income tax purposes, the minimum quarterly distribution amount and the target distribution amounts may be adjusted to reflect the impact of that law on us.Our taxation as a corporation would materially reduce the cash available for distribution to unitholders and thus would likely substantially reduce the value of our units. Any distribution made to a unitholder at a time we are treated as a corporation would be (i) a taxable dividend to the extent of our current or accumulated earnings and profits, then (ii) a nontaxable return of capital to the extent of the unitholder’s adjusted tax basis in its units (determined separately for each unit), and thereafter (iii) taxable capital gain.

The remainder of this discussion is based on the opinion of Vinson & Elkins L.L.P. that we will be treated as a partnership for federal income tax purposes.

Tax Consequences of Unit Ownership

Limited Partner Status

Unitholders of Westlake Chemical Partners LP who are admitted as limited partners of the partnership, as well as unitholders whose units are held in street name or by a nominee and who have the right to direct the nominee in the exercise of all substantive rights attendant to the ownership of their units will be treated as partners of Westlake Chemical Partners LP for federal income tax purposes.

In addition, a beneficial owner of units whose units have been transferred to a short seller to complete a short sale would appear to lose status as a partner with respect to such units for federal income tax purposes. Please read “—Tax Consequences of Unit Ownership—Treatment of Securities Loans.”

Income, gain, deductions or losses would not appear to be reportable by a unitholder who is not a partner for federal income tax purposes, and any cash distributions received by a unitholder who is not a partner for federal income tax purposes would therefore appear to be fully taxable as ordinary income. A unitholder who is not treated as a partner in us as described above are urged to consult its own tax advisors with respect to the tax consequences applicable to such unitholder under its particular circumstances.

Flow-Through of Taxable Income

Subject to the discussion below under “—Entity-Level Collections of Unitholder Taxes” and “—Administrative Matters—Information Returns and Audit Procedures”, with respect to payments we may be required to make on behalf of our unitholders, we will not pay any federal income tax. Rather, each unitholder will be required to report on its federal income tax return each year its share of our income, gains, losses and deductions for our taxable year or years ending with or within its taxable year. Consequently, we may allocate income to a unitholder even if that unitholder has not received a cash distribution.

Basis of Units

A unitholder’s tax basis in its units initially will be the amount paid for those units increased by the unitholder’s initial allocable share of our liabilities. That basis generally will be (i) increased by the unitholder’s share of our income and any increases in such unitholder’s share of our liabilities, and (ii) decreased, but not below zero, by the amount of all distributions to the unitholder, the unitholder’s share of our losses, and any decreases in its share of our liabilities. The IRS has ruled that a partner who acquires interests in a partnership in separate transactions must combine those interests and maintain a single adjusted tax basis for all of those interests.

Treatment of Distributions

Distributions made by us to a unitholder generally will not be taxable to the unitholder, unless such distributions are of cash or marketable securities that are treated as cash and exceed the unitholder’s tax basis in its units, in which case the unitholder generally will recognize gain taxable in the manner described below under “—Disposition of Units.”

Any reduction in a unitholder’s share of our “nonrecourse liabilities” (liabilities for which no partner bears the economic risk of loss) will be treated as a distribution by us of cash to that unitholder. A decrease in a unitholder’s percentage interest in us because of our issuance of additional units may decrease the unitholder’s share of our nonrecourse liabilities. For purposes of the foregoing, a unitholder’s share of our nonrecourse liabilities generally will be based upon that unitholder’s share of the unrealized appreciation (or depreciation) in our assets, to the extent thereof, with any excess nonrecourse liabilities allocated based on the unitholder’s share of our profits. Please read “—Disposition of Units.”

Anon-pro rata distribution of money or property (including a deemed distribution as a result of the reallocation of our nonrecourse liabilities described above) may cause a unitholder to recognize ordinary income if the distribution reduces the unitholder’s share of our “unrealized receivables,” including depreciation recapture and substantially appreciated “inventory items,” both as defined in Section 751 of the Code (“Section 751 Assets”). To the extent of such reduction, the unitholder would be deemed to receive its proportionate share of the Section 751 Assets and exchange such assets with us in return for a portion of thenon-pro rata distribution. This deemed exchange will result in the unitholder’s recognition of ordinary income in an amount equal to the excess of (1) thenon-pro rata portion of that distribution over (2) the unitholder’s tax basis (typically zero) in the Section 751 Assets deemed to be relinquished in the exchange.

Limitations on Deductibility of Losses

A unitholder may not be entitled to deduct the full amount of loss we allocate to it because its share of our losses will be limited to the lesser of (i) the unitholder’s adjusted tax basis in its units, and (ii) in the case of a unitholder that is an individual, estate, trust or certain types of closely-held corporations, the amount for which the unitholder is considered to be “at risk” with respect to our activities. A unitholder will be at risk to the extent of its adjusted tax basis in its units, reduced by (1) any portion of that basis attributable to the unitholder’s share of our nonrecourse liabilities, (2) any portion of that basis representing amounts otherwise protected against loss because of a guarantee, stop loss agreement or similar arrangement, and (3) any amount of money the unitholder borrows to acquire or hold its units, if the lender of those borrowed funds owns an interest in us, is related to another unitholder or can look only to the units for repayment. A unitholder subject to the at risk limitation must recapture losses deducted in previous years to the extent that distributions (including distributions deemed to result from a reduction in a unitholder’s share of nonrecourse liabilities) cause the unitholder’s at risk amount to be less than zero at the end of any taxable year.

Losses disallowed to a unitholder or recaptured as a result of the basis or at risk limitations will carry forward and will be allowable as a deduction in a later year to the extent that the unitholder’s adjusted tax basis or at risk amount, whichever is the limiting factor, is subsequently increased. Upon a taxable disposition of units, any gain recognized by a unitholder can be offset by losses that were previously suspended by the at risk limitation but not losses suspended by the basis limitation. Any loss previously suspended by the at risk limitation in excess of that gain can no longer be used, and will not be available to offset a unitholder’s salary or active business income.

In addition to the basis and at risk limitations, a passive activity loss limitation limits the deductibility of losses incurred by individuals, estates, trusts, some closely-held corporations and personal service corporations from “passive activities” (such as, trade or business activities in which the taxpayer does not materially participate). The passive loss limitations are applied separately with respect to each publicly-traded partnership. Consequently, any passive losses we generate will be available to offset only passive income generated by us. Passive losses that exceed a unitholder’s share of passive income we generate may be deducted in full when the unitholder disposes of all of its units in a fully taxable transaction with an unrelated party. The passive loss rules are applied after other applicable limitations on deductions, including the at risk and basis limitations.

Limitations on Interest Deductions

The deductibility of anon-corporate taxpayer’s “investment interest expense” is limited to the amount of that taxpayer’s “net investment income.” Investment interest expense includes:

•

interest on indebtedness allocable to property held for investment;

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interest expense allocated against portfolio income; and

•

the portion of interest expense incurred to purchase or carry an interest in a passive activity to the extent allocable against portfolio income.

Entity-Level Collections of Unitholder Taxes

If we are required or elect under applicable law to pay any federal, state, local ornon-U.S. tax on behalf of any current or former unitholder or our general partner, our partnership agreement authorizes us to treat the payment as a distribution of cash to the relevant unitholder or general partner. Where the tax is payable on behalf of all unitholders or we cannot determine the specific unitholder on whose behalf the tax is payable, our partnership agreement authorizes us to treat the payment as a distribution to all current unitholders. Payments by us as described above could give rise to an overpayment of tax on behalf of a unitholder, in which event the unitholder may be entitled to claim a refund of the overpayment amount. Please read “—Administrative Matters—Information Returns and Audit Procedures”. Each unitholder is urged to consult its tax advisor to determine the consequences to them of any tax payment we make on its behalf.

Allocation of Income, Gain, Loss and Deduction

In general, if we have a net profit, our items of income, gain, loss and deduction will be allocated amongst our unitholders and our general partner in accordance with their percentage interests in us. If distributions are made in respect of the incentive distribution rights, gross income will be allocated to the recipients to the extent of such distributions. In addition, for any taxable year ending on or before December 31, 2020, holders of common units (excluding converted subordinated units held by Westlake or its affiliates) may be allocated additional gross operating income; provided that no such special allocation shall be made to the extent a purchaser of common units in this offering would be allocated an amount of U.S. federal taxable income on the common units purchased in this offering with respect to such taxable year that would exceed 20% of the cash distributed on the common units purchased in this offering with respect to such year.

Specified items of our income, gain, loss and deduction will be allocated under Section 704(c) of the Code (or the principles of Section 704(c) of the Code) to account for any difference between the adjusted tax basis and fair market value of our assets at the time such assets are contributed to us and at the time of any subsequent offering of our units (a“Book-Tax Disparity”). As a result, the federal income tax burden associated with anyBook-Tax Disparity immediately prior to an offering will be borne by our partners holding interests in us prior to such offering. In addition, items of recapture income will be specially allocated to the extent possible (subject to the limitations described above) to the unitholder who was allocated the deduction giving rise to that recapture income in order to minimize the recognition of ordinary income by other unitholders.

An allocation of items of our income, gain, loss or deduction, other than an allocation required by the Code to eliminate aBook-Tax Disparity, will be given effect for federal income tax purposes in determining a unitholder’s share of an item of income, gain, loss or deduction only if the allocation has “substantial economic effect.” In any other case, a unitholder’s share of an item will be determined on the basis of the unitholder’s interest in us, which will be determined by taking into account all the facts and circumstances, including (i) the unitholder’s relative contributions to us, (ii) the interests of all the partners in profits and losses, (iii) the interest of all the partners in cash flow and (iv) the rights of all the partners to distributions of capital upon liquidation. Vinson & Elkins L.L.P. is of the opinion that, with the exception of the issues described in “— Section 754 Election” and “— Disposition of Units — Allocations Between Transferors and Transferees,” allocations of income, gain, loss or deduction under our partnership agreement will be given effect for federal income tax purposes.

Treatment of Securities Loans

A unitholder whose units are loaned (for example, a loan to a “short seller” to cover a short sale of units) may be treated as having disposed of those units. If so, such unitholder would no longer be treated for tax purposes as a partner with respect to those units during the period of the loan and may recognize gain or loss as a result of such deemed disposition. As a result, during this period (i) any of our income, gain, loss or deduction allocated to those units would not be reportable by the lending unitholder, and (ii) any cash distributions received by the lending unitholder as to those units may be treated as ordinary taxable income.

Due to a lack of controlling authority, Vinson & Elkins L.L.P. has not rendered an opinion regarding the tax treatment of a unitholder that enters into a securities loan with respect to its units. A unitholder desiring to assure its status as partners and avoid the risk of income recognition from a loan of its units is urged to modify any applicable brokerage account agreements to prohibit its brokers from borrowing and lending its units. The IRS has announced that it is studying issues relating to the tax treatment of short sales of partnership interests. Please read “—Disposition of Units—Recognition of Gain or Loss.”

Tax Rates

Under current law, the highest marginal federal income tax rates for individuals applicable to ordinary income and long-term capital gains (generally, gains from the sale or exchange of certain investment assets held for more than one year) are 39.6% and 20%, respectively. These rates are subject to change by new legislation at any time.

In addition, a 3.8% net investment income tax (“NIIT”) applies to certain net investment income earned by individuals, estates, and trusts. For these purposes, net investment income generally includes a unitholder’s allocable share of our income and gain realized by a unitholder from a sale of units. In the case of an individual, the tax will be imposed on the lesser of (i) the unitholder’s net investment income from all investments, or (ii) the amount by which the unitholder’s modified adjusted gross income exceeds $250,000 (if the unitholder is married and filing jointly or a surviving spouse), $125,000 (if married filing separately) or $200,000 (if the unitholder is unmarried or in any other case). In the case of an estate or trust, the tax will be imposed on the lesser of (i) undistributed net investment income, or (ii) the excess adjusted gross income over the dollar amount at which the highest income tax bracket applicable to an estate or trust begins.

Section 754 Election We have made the election permitted by Section 754 of the Code that permits us to adjust the tax bases in our assets as to specific purchasers of our units under Section 743(b) of the Code to reflect the unit purchase price. That election is irrevocable without the consent of the IRS. The Section 743(b) adjustment separately applies to each purchaser of units based upon the values and adjusted tax basis of each of our assets at the time of the relevant purchase, and the adjustment will reflect the purchase price paid. The Section 743(b) adjustment does not apply to a person who purchases units directly from us. For purposes of this discussion, a unitholder’s basis in our assets will be considered to have two components: (1) its share of the tax basis in our assets as to all unitholders and (2) its Section 743(b) adjustment to that tax basis (which may be positive or negative). The Section 743(b) adjustment does not apply to a person who purchases units directly from us.

Under Treasury Regulations, a Section 743(b) adjustment attributable to property depreciable under Section 168 of the Code, may be amortizable over the remaining cost recovery period for such property, while a Section 743(b) adjustment attributable to properties subject to depreciation under Section 167 of the Code, must be amortized straight-line or using the 150% declining balance method. As a result, if we owned any assets subject to depreciation under Section 167 of the Code, the amortization rates could give rise to differences in the taxation of unitholders purchasing units from us and unitholders purchasing from other unitholders.

Under our partnership agreement, we are authorized to take a position to preserve the uniformity of units even if that position is not consistent with applicable Treasury Regulations. Please read “—Disposition of Units—Uniformity of Units.” Consistent with our partnership agreement, we intend to treat properties depreciable under Section 167 of the Code, if any, in the same manner as properties depreciable under Section 168 of the Code for this purpose. These positions are consistent with the methods employed by other publicly traded partnerships but are inconsistent with the existing Treasury Regulations, and Vinson & Elkins L.L.P. has not opined on the validity of this approach.

The IRS may challenge the positions we adopt with respect to depreciating or amortizing the Section 743(b) adjustment to preserve the uniformity of units due to lack of controlling authority. Because a unitholder’s

adjusted tax basis for its units is reduced by its share of our items of deduction or loss, any position we take that understates deductions will overstate a unitholder’s basis in its units, and may cause the unitholder to understate gain or overstate loss on any sale of such units. Please read “— Disposition of Units — Recognition of Gain or Loss.” If a challenge to such treatment were sustained, the gain from the sale of units may be increased without the benefit of additional deductions.

The calculations involved in the Section 754 election are complex and are made on the basis of assumptions as to the value of our assets and other matters. The IRS could seek to reallocate some or all of any Section 743(b) adjustment we allocated to our assets subject to depreciation to goodwill or nondepreciable assets. Goodwill, as an intangible asset, is amortizable over a longer period of time or under a less accelerated method than certain of our tangible assets. We cannot assure any unitholder that the determinations we make will not be successfully challenged by the IRS or that the resulting deductions will not be reduced or disallowed altogether. Should the IRS require a different tax basis adjustment to be made, and should, in our opinion, the expense of compliance exceed the benefit of the election, we may seek permission from the IRS to revoke our Section 754 election. If permission is granted, a subsequent purchaser of units may be allocated more income than it would have been allocated had the election not been revoked.

Tax Treatment of Operations

Accounting Method and Taxable Year

We will use the year ending December 31 as our taxable year and the accrual method of accounting for federal income tax purposes. Each unitholder will be required to include in its tax return its share of our income, gain, loss and deduction for each taxable year ending within or with its taxable year. In addition, a unitholder who has a taxable year ending on a date other than December 31 and who disposes of all of its units following the close of our taxable year but before the close of its taxable year must include its share of our income, gain, loss and deduction in income for its taxable year, with the result that it will be required to include in income for its taxable year its share of more than twelve months of our income, gain, loss and deduction. Please read “—Disposition of Units—Allocations Between Transferors and Transferees.”

Tax Basis, Depreciation and Amortization

The tax basis of each of our assets will be used for purposes of computing depreciation and cost recovery deductions and, ultimately, gain or loss on the disposition of these assets. If we dispose of depreciable property by sale, foreclosure or otherwise, all or a portion of any gain, determined by reference to the amount of depreciation and deductions previously taken, may be subject to the recapture rules and taxed as ordinary income rather than capital gain. Similarly, a unitholder who has taken cost recovery or depreciation deductions with respect to property we own will likely be required to recapture some or all of those deductions as ordinary income upon a sale of its interest in us. Please read “—Tax Consequences of Unit Ownership—Allocation of Income, Gain, Loss and Deduction” and “—Disposition of Units – Recognition of Gain or Loss.”

The costs we incur in offering and selling our units (called “syndication expenses”) must be capitalized and cannot be deducted currently, ratably or upon our termination. While there are uncertainties regarding the classification of certain costs as organization expenses, which may be amortized by us, and as syndication expenses, which may not be amortized by us, the underwriting discounts and commissions we incur will be treated as syndication expenses. Please read “Disposition of Units – Recognition of Gain or Loss.”

Valuation and Tax Basis of Each of Our Properties

The federal income tax consequences of the ownership and disposition of units will depend in part on our estimates of the relative fair market values and the tax basis of each of our assets. Although we may from time to time consult with professional appraisers regarding valuation matters, we will make many of the relative fair

market value estimates ourselves. These estimates and determinations of tax basis are subject to challenge and will not be binding on the IRS or the courts. If the estimates of fair market value or basis are later found to be incorrect, the character and amount of items of income, gain, loss or deduction previously reported by a unitholder could change, and such unitholder could be required to adjust its tax liability for prior years and incur interest and penalties with respect to those adjustments.

Disposition of Units

Recognition of Gain or Loss

Except as noted below, gain or loss recognized by a unitholder on the sale or exchange of a unit held for more than one year generally will be taxable as long-term capital gain or loss. However, gain or loss recognized on the disposition of units will be separately computed and taxed as ordinary income or loss under Section 751 of the Code to the extent attributable to Section 751 Assets, such as depreciation recapture and our “inventory items,” regardless of whether such inventory item is substantially appreciated in value. Ordinary income attributable to Section 751 Assets may exceed net taxable gain realized on the sale or exchange of a unit and may be recognized even if there is a net taxable loss realized on the sale or exchange of a unit. Thus, a unitholder may recognize both ordinary income and capital gain or loss upon a sale or exchange of a unit. Net capital loss may offset capital gains and, in the case of individuals, up to $3,000 of ordinary income per year.

Treasury Regulations under Section 1223 of the Code allow a selling unitholder who can identify units transferred with an ascertainable holding period to elect to use the actual holding period of the units transferred. Thus, according to the ruling discussed in the paragraph above, a unitholder will be unable to select high or low basis units to sell or exchange as would be the case with corporate stock, but, according to the Treasury Regulations, it may designate specific units sold for purposes of determining the holding period of the units transferred. A unitholder electing to use the actual holding period of any unit transferred must consistently use that identification method for all subsequent sales or exchanges of our units. A unitholder considering the purchase of additional units or a sale or exchange of units purchased in separate transactions is urged to consult its tax advisor as to the possible consequences of this ruling and application of the Treasury Regulations.

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a short sale;

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an offsetting notional principal contract; or

•

a futures or forward contract with respect to the partnership interest or substantially identical property.

Allocations Between Transferors and Transferees

In general, our taxable income or loss will be determined annually, will be prorated on a monthly basis and will be subsequently apportioned among the unitholders in proportion to the number of units owned by each of them as of the opening of the applicable exchange on the first business day of the month (the “Allocation Date”). Nevertheless, we allocate certain deductions for depreciation of capital additions based upon the date the underlying property is placed in service, and gain or loss realized on a sale or other disposition of our assets or, in the discretion of the general partner, any other extraordinary item of income, gain, loss or deduction will be allocated among the unitholders on the Allocation Date in the month in which such income, gain, loss or deduction is recognized. As a result, a unitholder transferring units may be allocated income, gain, loss and deduction realized after the date of transfer.

Although simplifying conventions are contemplated by the Code and most publicly traded partnerships use similar simplifying conventions, the use of this method may not be permitted under existing Treasury Regulations. The Department of the Treasury and the IRS issued final Treasury Regulations pursuant to which a publicly traded partnership may use a similar monthly simplifying convention to allocate tax items among transferor and transferee unitholders. Nonetheless, the regulations do not specifically authorize the use of the proration method we have adopted. Accordingly, Vinson & Elkins L.L.P. is unable to opine on the validity of this method of allocating income and deductions between transferee and transferor unitholders. If the IRS determines that this method is not allowed under the final Treasury Regulations our taxable income or losses could be reallocated among our unitholders. Under our partnership agreement, we are authorized to revise our method of allocation between transferee and transferor unitholders, as well as among unitholders whose interests vary during a taxable year, to conform to a method permitted under the Treasury Regulations.

A unitholder who disposes of units prior to the record date set for a cash distribution for that quarter will be allocated items of our income, gain, loss and deduction attributable to the month of disposition but will not be entitled to receive a cash distribution for that period.

Notification Requirements

A unitholder who sells or purchases any of its units is generally required to notify us in writing of that transaction within 30 days after the transaction (or, if earlier, January 15 of the year following the transaction in the case of a seller). Upon receiving such notifications, we are required to notify the IRS of that transaction and to furnish specified information to the transferor and transferee. Failure to notify us of a transfer of units may, in some cases, lead to the imposition of penalties. However, these reporting requirements do not apply to a sale by an individual who is a citizen of the United States and who effects the sale through a broker who will satisfy such requirements.

Technical Termination

We will be considered to have technically terminated our partnership for federal income tax purposes upon the sale or exchange of 50% or more of the total interests in our capital and profits within a twelve-month period.

For purposes of measuring whether the 50% threshold is reached, multiple sales of the same unit are counted only once. A technical termination results in the closing of our taxable year for all unitholders. In the case of a unitholder reporting on a taxable year other than the calendar year, the closing of our taxable year may result in more than twelve months of our taxable income or loss being includable in such unitholder’s taxable income for the year of termination.

A technical termination occurring on a date other than December 31 would require that we file two tax returns for one fiscal year, thereby increasing our administration and tax preparation costs. However, pursuant to an IRS relief procedure the IRS may allow a technically terminated partnership to provide a single ScheduleK-1 for the calendar year in which a termination occurs. Following a technical termination, we would be required to make new tax elections, including a new election under Section 754 of the Code, and the termination would result in a deferral of our deductions for depreciation and thus may increase the taxable income allocable to our unitholders. A technical termination could also result in penalties if we were unable to determine that the technical termination had occurred. Moreover, a technical termination may either accelerate the application of, or subject us to, any tax legislation enacted before the technical termination that would not otherwise have been applied to us as a continuing partnership as opposed to a terminating partnership.

Uniformity of Units

Because we cannot match transferors and transferees of units and for other reasons, we must maintain uniformity of the economic and tax characteristics of the units to a purchaser of these units. As a result of the need to preserve uniformity, we may be unable to completely comply with a number of federal income tax requirements. Anynon-uniformity could have a negative impact on the value of the units. Please read “—Tax Consequences of Unit Ownership—Section 754 Election.”

Our partnership agreement permits our general partner to take positions in filing our tax returns that preserve the uniformity of our units. These positions may include reducing the depreciation, amortization or loss deductions to which a unitholder would otherwise be entitled or reporting a slower amortization of Section 743(b) adjustments for some unitholders than that to which they would otherwise be entitled. Vinson & Elkins L.L.P. is unable to opine as to the validity of such filing positions.

A unitholder’s adjusted tax basis in units is reduced by its share of our deductions (whether or not such deductions were claimed on an individual income tax return) so that any position that we take that understates deductions will overstate the unitholder’s basis in its units, and may cause the unitholder to understate gain or overstate loss on any sale of such units. Please read “— Disposition of Units—Recognition of Gain or Loss” and “—Tax Consequences of Unit Ownership—Section 754 Election” above. The IRS may challenge one or more of any positions we take to preserve the uniformity of units. If such a challenge were sustained, the uniformity of units might be affected, and, under some circumstances, the gain from the sale of units might be increased without the benefit of additional deductions.

Tax-Exempt Organizations and Other Investors

Ownership of units by employee benefit plans and othertax-exempt organizations, as well as bynon-resident alien individuals,non-U.S. corporations and othernon-U.S. persons (collectively,“Non-U.S. Unitholders”) raises issues unique to those investors and, as described below, may have substantially adverse tax consequences to them. Each prospective unitholder that is atax-exempt entity orNon-U.S. Unitholder should consult its tax advisors before investing in our units.

Non-U.S. Unitholders are taxed by the United States on income effectively connected with a U.S. trade or business (“effectively connected income”) and on certain types of U.S.-sourcenon-effectively connected income (such as dividends), unless exempted or further limited by an income tax treaty. EachNon-U.S. Unitholder will be considered to be engaged in business in the United States because of its ownership of our units. Furthermore, it is probable thatNon-U.S. Unitholders will be deemed to conduct such activities through a permanent establishment in the United States within the meaning of any applicable tax treaty. Consequently, eachNon-U.S. Unitholder will be required to file federal tax returns to report its share of our income, gain, loss or deduction and pay federal income tax on its share of our net income or gain. Moreover, under rules applicable to publicly traded partnerships, distributions toNon-U.S. Unitholders are subject to withholding at the highest applicable effective tax rate. EachNon-U.S. Unitholder must obtain a taxpayer identification number from the IRS and submit that number to our transfer agent on a FormW-8BEN orW-8BEN-E (or other applicable or successor form) in order to obtain credit for these withholding taxes.

In addition, if aNon-U.S. Unitholder is classified as anon-U.S. corporation, it will be treated as engaged in a United States trade or business and may be subject to the U.S. branch profits tax at a rate of 30%, in addition to regular federal income tax, on its share of our income and gain as adjusted for changes in the foreign corporation’s “U.S. net equity” to the extent reflected in the corporation’s earnings and profits. That tax may be reduced or eliminated by an income tax treaty between the United States and the country in which the foreign corporate unitholder is a “qualified resident.” In addition, this type of unitholder is subject to special information reporting requirements under Section 6038C of the Code.

ANon-U.S. Unitholder who sells or otherwise disposes of a unit will be subject to federal income tax on gain realized from the sale or disposition of that unit to the extent the gain is effectively connected with a U.S. trade or business of theNon-U.S. Unitholder. Under a ruling published by the IRS interpreting the scope of “effectively connected income,” gain realized by aNon-U.S. Unitholder from the sale of its interest in a partnership that is engaged in a trade or business in the United States will be considered to be “effectively connected” with a U.S. trade or business. Thus, part or all of aNon-U.S. Unitholder’s gain from the sale or other disposition of units may be treated as effectively connected with a unitholder’s indirect U.S. trade or business constituted by its investment in us.

Moreover, under the Foreign Investment in Real Property Tax Act, as long as our partnership units continue to be regularly traded on an established securities marker, aNon-U.S. Unitholder generally will only be subject to federal income tax upon the sale or disposition of a unit if at any time during the shorter of the five-year period ending on the date of the disposition or theNon-U.S. Unitholder’s holding period for the unit (i) suchNon-U.S. Unitholder owned (directly or indirectly constructively applying certain attribution rules) more than 5% of our units and (ii) 50% or more of the fair market value of our real property interests and other assets used or held for use in a trade or business consisted of U.S. real property interests (which include U.S. real estate, including land, improvements, and associated personal property, and interests in certain entities holding U.S. real estate). If our units were not considered to be regularly traded on an established securities market, suchNon-U.S. Unitholder (regardless of the percentage of units owned) would be subject to U.S. federal income tax on a taxable disposition of our units, and a 15% withholding tax would apply to the gross proceeds from such disposition (as described in the preceding paragraph). More than 50% of our assets may consist of U.S. real property interests. Therefore, eachNon-U.S. Unitholder may be subject to federal income tax on gain from the sale or disposition of its units.

Administrative Matters

Information Returns and Audit Procedures

various accounting and reporting positions, some of which have been mentioned earlier, to determine each unitholder’s share of income, gain, loss and deduction. We cannot assure our unitholders that those positions will yield a result that conforms to all of the requirements of the Code, Treasury Regulations or administrative interpretations of the IRS.

The IRS may audit our federal income tax information returns. Neither we nor Vinson & Elkins L.L.P. can assure prospective unitholders that the IRS will not successfully challenge the positions we adopt, and such a challenge could adversely affect the value of the units. Adjustments resulting from an IRS audit may require each unitholder to adjust a prior year’s tax liability, and may result in an audit of the unitholder’s own return. Any audit of a unitholder’s return could result in adjustments unrelated to our returns.

Publicly traded partnerships are treated as entities separate from its owners for purposes of federal income tax audits, judicial review of administrative adjustments by the IRS and tax settlement proceedings. The tax treatment of partnership items of income, gain, loss and deduction are determined in a partnership proceeding rather than in separate proceedings of the partners. The Code requires that one partner be designated as the “Tax Matters Partner” for these purposes, and our partnership agreement designates our general partner.

The Tax Matters Partner can extend the statute of limitations for assessment of tax deficiencies against unitholders for items in our returns. The Tax Matters Partner may bind a unitholder with less than a 1% profits interest in us to a settlement with the IRS unless that unitholder elects, by filing a statement with the IRS, not to give that authority to the Tax Matters Partner. The Tax Matters Partner may seek judicial review, by which all the unitholders are bound, of a final partnership administrative adjustment and, if the Tax Matters Partner fails to seek judicial review, judicial review may be sought by any unitholder having at least a 1% interest in profits or by any group of unitholders having in the aggregate at least a 5% interest in profits. However, only one action for judicial review may go forward, and each unitholder with an interest in the outcome may participate in that action.

A unitholder must file a statement with the IRS identifying the treatment of any item on its federal income tax return that is not consistent with the treatment of the item on our return. Intentional or negligent disregard of this consistency requirement may subject a unitholder to substantial penalties.

Pursuant to the Bipartisan Budget Act of 2015, for taxable years beginning after December 31, 2017, if the IRS makes audit adjustments to our income tax returns, it may assess and collect any taxes (including any applicable penalties and interest) resulting from such audit adjustment directly from us, unless we elect to have our general partner and unitholders take any audit adjustment into account in accordance with their interests in us during the taxable year under audit. Similarly, for such taxable years, if the IRS makes audit adjustments to income tax returns filed by an entity in which we are a member or partner, it may assess and collect any taxes (including penalties and interest) resulting from such audit adjustment directly from such entity. Generally, we expect to elect to have our general partner and unitholders take any such audit adjustment into account in accordance with their interests in us during the taxable year under audit, but there can be no assurance that such election will be effective in all circumstances. With respect to audit adjustments as to an entity in which we are a member or partner, the Joint Committee of Taxation has stated that we would not be able to have our general partner and our unitholders take such audit adjustment into account. If we are unable to have our general partner and our unitholders take such audit adjustment into account in accordance with their interests in us during the taxable year under audit, our then current unitholders may bear some or all of the tax liability resulting from such audit adjustment, even if such unitholders did not own our units during the taxable year under audit. If, as a result of any such audit adjustment, we are required to make payments of taxes, penalties, and interest, our cash available for distribution to our unitholders might be substantially reduced. These rules are not applicable for taxable years beginning on or prior to December 31, 2017. Congress has proposed changes to the Bipartisan Budget Act, and we anticipate that amendments may be made. Accordingly, the manner in which these rules may apply to us in the future is uncertain.

Additional Withholding Requirements

Withholding taxes may apply to certain types of payments made to “foreign financial institutions” (as specially defined in the Code) and certain other foreign entities. Specifically, a 30% withholding tax may be imposed on interest, dividends and other fixed or determinable annual or periodical gains, profits and income from sources within the United States (“FDAP Income”), or gross proceeds from the sale or other disposition of any property of a type which can produce interest or dividends from sources within the United States (“Gross Proceeds”) paid to a foreign financial institution or to a“non-financial foreign entity” (as specially defined in the Code), unless (i) the foreign financial institution undertakes certain diligence and reporting, (ii) thenon-financial foreign entity either certifies it does not have any substantial U.S. owners or furnishes identifying information regarding each substantial U.S. owner or (iii) the foreign financial institution ornon-financial foreign entity otherwise qualifies for an exemption from these rules. If the payee is a foreign financial institution and is subject to the diligence and reporting requirements in clause (i) above, it must enter into an agreement with the U.S. Department of the Treasury requiring, among other things, that it undertake to identify accounts held by certain U.S. persons or U.S.-owned foreign entities, annually report certain information about such accounts, and withhold 30% on payments to noncompliant foreign financial institutions and certain other account holders. Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing these requirements may be subject to different rules.

These rules generally apply to payments of FDAP Income currently and generally will apply to payments of relevant Gross Proceeds made on or after January 1, 2019. Thus, to the extent we have FDAP Income or we have Gross Proceeds on or after January 1, 2019 that are not treated as effectively connected with a U.S. trade or business (please read“—Tax-Exempt Organizations and Other Investors—Income Allocations, Distributions and Dispositions”), a unitholder who is foreign financial institution or certain other foreign entity, or a person that hold its units through such foreign entities, may be subject to withholding on distributions they receive from us, or its distributive share of our income, pursuant to the rules described above.

Each prospective unitholder should consult its own tax advisors regarding the potential application of these withholding provisions to its investment in our units.

Nominee Reporting

Persons who hold an interest in us as a nominee for another person are required to furnish to us:

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the name, address and taxpayer identification number of the beneficial owner and the nominee;

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a statement regarding whether the beneficial owner is:

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anon-U.S. person;

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anon-U.S. government, an international organization or any wholly-owned agency or instrumentality of either of the foregoing; or

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atax-exempt entity;

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the amount and description of units held, acquired or transferred for the beneficial owner; and

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specific information including the dates of acquisitions and transfers, means of acquisitions and transfers, and acquisition cost for purchases, as well as the amount of net proceeds from sales.

Each broker and financial institution is required to furnish additional information, including whether such broker or financial institution is a U.S. person and specific information on units such broker or financial institution acquires, holds or transfers for its own account. A penalty of $250 per failure, up to a maximum of $3 million per calendar year, is imposed by the Code for failure to report that information to us. The nominee is required to supply the beneficial owner of the units with the information furnished to us.

Accuracy-Related Penalties

State, Local, and Other Tax Considerations

In addition to federal income taxes, unitholders may be subject to other taxes, including state and local income taxes, unincorporated business taxes, and estate, inheritance or intangibles taxes that may be imposed by the various jurisdictions in which we conduct business or own property now or in the future or in which the unitholder is a resident. We will initially own assets and conduct business in Kentucky, Louisiana, and Texas; Kentucky and Louisiana currently impose a personal income tax on individuals, corporations, and other entities. As we make acquisitions or expand our business, we may own property or conduct business in additional states that impose a personal income tax. Although an analysis of those various taxes is not presented here, each prospective unitholder should consider its potential impact on its investment in us.

It is the responsibility of each unitholder to investigate the legal and tax consequences, under the laws of pertinent jurisdictions, of its investment in us. We strongly recommend that each prospective unitholder consult, and depend upon, its own tax counsel or other advisor with regard to those matters. Further, it is the responsibility of each unitholder to file all state, local andnon-U.S., as well as federal tax returns that may be required of it. Vinson & Elkins L.L.P. has not rendered an opinion on the state, local, alternative minimum tax ornon-U.S. tax consequences of an investment in us.

MATERIAL U.S. TAX CONSEQUENCES OF OWNERSHIP OF DEBT SECURITIES

A description of the material U.S. federal income tax consequences of the acquisition, ownership and disposition of debt securities will be set forth on the prospectus supplement relating to the offering of debt securities.

CERTAIN ERISA CONSIDERATIONS

The following is a summary of certain considerations associated with the acquisition and holding of our common units by employee benefit plans that are subject to Title I of ERISA, plans, individual retirement accounts and other arrangements that are subject to Section 4975 of the Code or employee benefit plans that are governmental plans (as defined in Section 3(32) of ERISA), certain church plans (as defined in Section 3(33) of ERISA),non-U.S. plans (as described in Section 4(b)(4) of ERISA) or other plans that are not subject to the foregoing but may be subject to provisions under any other federal, state, local,non-U.S. or other laws or regulations that are similar to such provisions of ERISA or the Code (collectively, “Similar Laws”), and entities whose underlying assets are considered to include “plan assets” of any such plan, account or arrangement (each, a “Plan”).

This summary is based on the provisions of ERISA and the Code (and related regulations and administrative and judicial interpretations) as of the date of this prospectus. This summary does not purport to be complete, and no assurance can be given that future legislation, court decisions, regulations, rulings or pronouncements will not significantly modify the requirements summarized below. Any of these changes may be retroactive and may thereby apply to transactions entered into prior to the date of their enactment or release. This discussion is general in nature and is not intended to be all inclusive, nor should it be construed as investment or legal advice.

General Fiduciary Matters

ERISA and the Code impose certain duties on persons who are fiduciaries of a Plan subject to Title I of ERISA or Section 4975 of the Code (an “ERISA Plan”) and prohibit certain transactions involving the assets of an ERISA Plan and its fiduciaries or other interested parties. Under ERISA and the Code, any person who exercises any discretionary authority or control over the administration of an ERISA Plan or the management or disposition of the assets of an ERISA Plan, or who renders investment advice for a fee or other compensation to an ERISA Plan, is generally considered to be a fiduciary of the ERISA Plan.

In considering an investment in our common units with a portion of the assets of any Plan, a fiduciary should consider the Plan’s particular circumstances and all of the facts and circumstances of the investment and determine whether the acquisition and holding of such units is in accordance with the documents and instruments governing the Plan and the applicable provisions of ERISA, the Code, or any Similar Law relating to the fiduciary’s duties to the Plan. Among other things, consideration should be given to:

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whether the investment is prudent under Section 404(a)(1)(B) of ERISA and any other applicable Similar Laws;

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whether, in making the investment, the Plan will satisfy the diversification requirements of Section 404(a)(1)(C) of ERISA and any other applicable Similar Laws;

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whether the investment is permitted under the terms of the applicable documents governing the Plan;

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whether the acquisition or holding of the common units will constitute a “prohibited transaction” under Section 406 of ERISA or Section 4975 of the Code (please see discussion under “—Prohibited Transaction Issues” below);

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whether the Plan will be considered to hold, as plan assets, (i) only common units or (ii) an undivided interest in our underlying assets (please see the discussion under “—Plan Asset Issues” below); and

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whether the investment will result in recognition of unrelated business taxable income by the Plan and, if so, the potentialafter-tax investment return. Please read “Material U.S. Federal Income Tax Consequences—Tax Exempt Organizations and Other Investors.”

Prohibited Transaction Issues

Section 406 of ERISA and Section 4975 of the Code prohibit ERISA Plans from engaging in specified transactions involving plan assets with persons or entities who are “parties in interest,” within the meaning of

ERISA, or “disqualified persons,” within the meaning of Section 4975 of the Code, unless an exemption is available. A party in interest or disqualified person who engages in anon-exempt prohibited transaction may be subject to excise taxes and other penalties and liabilities under ERISA and the Code. In addition, the fiduciary of the ERISA Plan that engages in such anon-exempt prohibited transaction may be subject to excise taxes, penalties and liabilities under ERISA and the Code. The acquisition and/or holding of our common units by an ERISA Plan with respect to which the issuer, the initial purchaser, or a guarantor is considered a party in interest or a disqualified person may constitute or result in a direct or indirect prohibited transaction under Section 406 of ERISA and/or Section 4975 of the Code, unless the investment is acquired and is held in accordance with an applicable statutory, class or individual prohibited transaction exemption.

Because of the foregoing, our common units should not be acquired or held by any person investing “plan assets” of any Plan, unless such acquisition and holding will not constitute anon-exempt prohibited transaction under ERISA and the Code or a similar violation of any applicable Similar Laws.

Plan Asset Issues

Additionally, a fiduciary of a Plan should consider whether the Plan will, by investing in us, be deemed to own an undivided interest in our assets, with the result that our general partner would become a fiduciary of the Plan and our operations would be subject to the regulatory restrictions of ERISA, including its prohibited transaction rules, as well as the prohibited transaction rules of the Code and any other applicable Similar Laws.

The U.S. Department of Labor (the “DOL”) regulations provide guidance with respect to whether the assets of an entity in which ERISA Plans acquire equity interests would be deemed “plan assets” under certain circumstances. Under these regulations, an entity’s underlying assets generally would not be considered to be “plan assets” if, among other things:

(a)

the units acquired by ERISA Plans are publicly offered securities—i.e., the units are part of a class of securities that is widely held by 100 or more investors independent of the issuer and each other, are “freely transferable” (as defined in the DOL regulations), and are either registered under certain provisions of the federal securities laws or sold to the ERISA Plan as part of a public offering under certain conditions;

(b)

the entity is an “operating company”—i.e., it is primarily engaged in the production or sale of a product or service, other than the investment of capital, either directly or through a majority-owned subsidiary or subsidiaries; or

(c)

there is no “significant” investment by “benefit plan investors” (as defined in Section 3(42) of ERISA), which is defined to mean that immediately after the most recent acquisition by a benefit plan investor of any equity interest in the entity, less than 25% of the total value of each class of equity interest (disregarding certain interests held by our general partner, its affiliates, and certain other persons (other than benefit plan investors) with discretionary authority or control over the assets of the entity or who provide investment advice for a fee (direct or indirect) with respect to such assets, and any affiliates thereof) is held by ERISA Plans, IRAs and certain other Plans (but not including governmental plans, foreign plans and certain church plans), and entities whose underlying assets are deemed to include plan assets by reason of a Plan’s investment in the entity.

Due to the complexity of these rules and the excise taxes, penalties and liabilities that may be imposed upon persons involved innon-exempt prohibited transactions, it is particularly important that fiduciaries, or other persons considering acquiring and/or holding our common units on behalf of, or with the assets of, any Plan, consult with their counsel regarding the potential applicability of ERISA, Section 4975 of the Code and any Similar Laws to such investment and whether an exemption would be applicable to the acquisition and holding of our common units. Purchasers of our common units have the exclusive responsibility for ensuring that their acquisition and holding of such units complies with the fiduciary responsibility rules of ERISA and does not

violate the prohibited transaction rules of ERISA, the Code or applicable Similar Laws. The sale of common units to a Plan is in no respect a representation by us or any of our affiliates or representatives that such an investment meets all relevant legal requirements with respect to investments by any such Plan or that such investment is appropriate for any such Plan.

PLAN OF DISTRIBUTION

The securities offered pursuant to this prospectus and any accompanying prospectus supplement may be sold in any of the following ways:

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directly to one or more purchasers;

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through agents;

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through underwriters, brokers or dealers; or

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through a combination of any of these methods of sale.

In addition, we may from time to time sell securities in compliance with Rule 144 under the Securities Act, if available, or pursuant to other available exemptions from the registration requirements under the Securities Act, rather than pursuant to this prospectus. In such event, we may be required by the securities laws of certain states to offer and sell the common units only through registered or licensed brokers or dealers.

We will fix a price or prices of our securities at:

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market prices prevailing at the time of any sale under this registration statement;

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prices related to market prices; or

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negotiated prices.

We may change the price of the securities offered from time to time.

Offers to purchase securities may be solicited directly by us and the sale thereof may be made by us directly to institutional investors or others. In this case, no underwriters or agents would be involved. We may use electronic media, including the internet, to sell offered securities directly.

We, or agents designated by us, may directly solicit, from time to time, offers to purchase the securities. Any such agent may be deemed to be an underwriter as that term is defined in the Securities Act. We will name any agents involved in the offer or sale of the securities and describe any commissions payable by us to these agents in the prospectus supplement. Unless otherwise indicated in the prospectus supplement, these agents will be acting on a best efforts basis for the period of their appointment. The agents may be entitled under agreements which may be entered into with us, to indemnification by us against specific civil liabilities, including liabilities under the Securities Act. The agents may also be our customers or may engage in transactions with or perform services for us in the ordinary course of business.

If we utilize any underwriters in the sale of the securities in respect of which this prospectus is delivered, we will enter into an underwriting agreement with those underwriters at the time of sale to them. We will set forth the names of these underwriters and the terms of the transaction in the prospectus supplement, which will be used by the underwriters to make resales of the securities in respect of which this prospectus is delivered to the public. We may indemnify the underwriters under the relevant underwriting agreement against specific liabilities, including liabilities under the Securities Act. The underwriters or their affiliates may be customers of, may engage in transactions with and may perform services for us or our affiliates in the ordinary course of business.

If we utilize a dealer in the sale of the securities in respect of which this prospectus is delivered, we will sell those securities to the dealer, as principal. The dealer may then resell those securities to the public at varying prices to be determined by the dealer at the time of resale. We may indemnify the dealers against specific liabilities, including liabilities under the Securities Act. The dealers or their affiliates may also be our customers or may engage in transactions with, or perform services for us in the ordinary course of business.

We may offer the common units covered by this prospectus into an existing trading market on the terms described in the prospectus supplement relating thereto. Underwriters, dealers and agents who participate in anyat-the-market offerings will be described in the prospectus supplement relating thereto.

A prospectus and accompanying prospectus supplement in electronic form may be made available on the websites maintained by the underwriters. The underwriters may agree to allocate a number of securities for sale to their online brokerage account holders. Such allocations of securities for internet distributions will be made on the same basis as other allocations. In addition, securities may be sold by the underwriters to securities dealers who resell securities to online brokerage account holders.

The aggregate maximum compensation the underwriters will receive in connection with the sale of any securities under this prospectus and the registration statement of which it forms a part will not exceed 10% of the gross proceeds from the sale.

Because the Financial Industry Regulatory Authority (“FINRA”) views our common units as interests in a direct participation program, any offering of common units under the registration statement of which this prospectus forms a part will be made in compliance with Rule 2310 of the FINRA Conduct Rules.

To the extent required, this prospectus may be amended or supplemented from time to time to describe a specific plan of distribution. The place and time of delivery for the securities in respect of which this prospectus is delivered will be set forth in the accompanying prospectus supplement.

In connection with offerings of securities under the registration statement of which this prospectus forms a part and in compliance with applicable law, underwriters, brokers or dealers may engage in transactions that stabilize or maintain the market price of the securities at levels above those that might otherwise prevail in the open market. Specifically, underwriters, brokers or dealers may over-allot in connection with offerings, creating a short position in the securities for their own accounts. For the purpose of covering a syndicate short position or stabilizing the price of the securities, the underwriters, brokers or dealers may place bids for the securities or effect purchases of the securities in the open market. Finally, the underwriters may impose a penalty whereby selling concessions allowed to syndicate members or other brokers or dealers for distribution of the securities in offerings may be reclaimed by the syndicate if the syndicate repurchases previously distributed securities in transactions to cover short positions, in stabilization transactions or otherwise. These activities may stabilize, maintain or otherwise affect the market price of the securities, which may be higher than the price that might otherwise prevail in the open market, and, if commenced, may be discontinued at any time.

LEGAL MATTERS

The validity of the issuance of, and the material federal income tax considerations regarding, the securities offered hereby will be passed upon for us by Vinson & Elkins L.L.P. Additional legal matters may be passed on for us, or any underwriters, dealers or agents, by counsel we will name in the applicable prospectus supplement.

EXPERTS

The financial statements and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) incorporated in this Prospectus by reference to the Annual Report on Form10-K for the year ended December 31, 2016 have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

LOGO

Westlake Chemical Partners LP

Common Units

Representing Limited Partner Interests

Having an Aggregate Offering Amount of Up to

$50,000,000

Prospectus Supplement

UBS Investment Bank

Barclays

BofA Merrill Lynch

Citigroup

Deutsche Bank Securities

RBC Capital Markets

Wells Fargo Securities

October 4, 2018

Westlake Chemical Partners (WLKP) 424B5Prospectus supplement for primary offering