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                                                                    EXHIBIT 3.20

                        AGREEMENT OF LIMITED PARTNERSHIP
                                       OF
                                XL SYSTEMS, L.P.

         THIS AGREEMENT OF LIMITED PARTNERSHIP of XL Systems, L.P. (the
"Partnership") is entered into by and between Grant Prideco Holding, LLC, a
Delaware limited liability company, as general partner (the "General Partner")
and Grant Prideco USA, LLC, a Delaware limited liability company, as limited
partner (the "Limited Partner").

         WHEREAS, the General Partner and the Limited Partner (collectively, the
"Shareholders"), are all of the shareholders of XL Systems, Inc., a Texas
corporation (the "Corporation");

         WHEREAS, the directors of the Corporation and the Shareholders have
determined that it is in the best interest of the Corporation to convert the
Corporation from a Texas corporation into a Texas limited partnership pursuant
to, and as authorized by, Article 5.17 of the Texas Business Corporation Act and
Section 2.15 of the Texas Revised Limited Partnership Act (the "TRLPA"); and

         WHEREAS, the Shareholders desire to form a limited partnership pursuant
to the Texas Revised Limited Partnership Act effective upon the filing of the
appropriate certificate required thereunder with the Secretary of State of the
State of Texas to accomplish and complete the conversion of the Corporation
described above and to carry out the Plan of Conversion adopted for the
Corporation.

         NOW, THEREFORE, in consideration of the mutual covenants, conditions
and agreements herein contained, the undersigned parties hereby agree as
follows:

         1. Name. The name of the limited partnership formed hereby is XL
Systems, L.P.

         2. Purpose. The purpose for which the Partnership is organized is to
transact any and all lawful business for which limited partnerships may be
organized under the TRLPA.

         3. Registered Office. The registered office of the Partnership in the
State of Texas is c/o The Corporation Service Company, 800 Brazos, Suite 750,
Austin, Texas 78701.

         4. Registered Agent. The name and address of the registered agent of
the Partnership for service of process on the Partnership in the State of Texas
is The Corporation Service Company, 800 Brazos, Suite 750, Austin, Texas 78701.

         5. Partners. The names and the business, residence or mailing addresses
of the General Partner and the Limited Partner are as follows:


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         General Partner

         Grant Prideco Holding, LLC
         1450 Lake Robbins Drive
         Suite 600
         The Woodlands, Texas 77380

         Limited Partner

         Grant Prideco USA, LLC
         1450 Lake Robbins Drive
         Suite 600
         The Woodlands, Texas 77380

         6. Powers. The Partnership shall have the power and authority to take
any and all actions necessary, appropriate, proper, advisable, convenient, or
incidental to or for the furtherance of the purposes set forth in Section 2,
including any and all powers set forth in the TRLPA.

         7. Term. The term of the Partnership shall commence on July 31, 2000 at
10:15 p.m. central standard time and shall be perpetual, unless it is dissolved
sooner as a result of: (a) an event of withdrawal of a general partner described
in Section 4.02 of the TRLPA, (b) the written consent of all of the partners of
the Partnership, (b) an entry of a decree of judicial dissolution under Section
8.02 of the TRLPA, or (c) any other event causing dissolution under the TRLPA.

         8. Capital Contributions.

                  a. Initial Capital Contributions. Following execution of this
         agreement, the General Partner shall contribute 1% of the Initial
         Capital Contribution (as hereinafter defined) to the Partnership and
         the Limited Partner shall contribute 99% of the Initial Capital
         Contribution to the Partnership. Initial Capital Contribution shall
         mean assets in the form and cash in the amount contributed by the
         Partners, upon the execution of this agreement, to the capital of the
         Partnership.

                  b. Subsequent Capital Contributions. The partners of the
         Partnership shall contribute such amounts, in cash or other property,
         to the Partnership as they may agree from time to time.

         9. No Further Liability. The liability of the Limited Partner to the
Partnership shall be limited to the amount of its capital contributions made
pursuant to Section 8(a) and 8(b), and the Limited Partner shall not have any
further liability to contribute money to, or in respect of, the liabilities or
the obligations of the Partnership unless it agrees in writing to make
additional capital contributions to the Partnership, nor shall the Limited
Partner be personally liable for any obligations of the Partnership, except as
may be provided in the Act.

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         10. Allocations of Profit and Losses. The Partnership's profits and
losses shall be allocated in proportion to the capital accounts of the partners
of the Partnership.

         11. Distributions. The Partnership shall make cash distributions to the
partners at such times and in such amounts as determined by the General Partner.
Cash available for distribution shall be distributed to the partners of the
Partnership in the same proportion as their then capital account balances.

         12. Tax Matters Partner. The General Partner is designated tax matters
partner as defined in section 6231(a)(7) of the Internal Revenue Code, of 1986,
as amended.

         13. Indemnification.

                  a. The General Partner, its affiliates, their respective
         officers, directors, employees and agents or any Person performing a
         similar function on behalf of the Partnership (individually, an
         "Indemnitee") may be indemnified and held harmless by the Partnership
         from and against any and all judgments, penalties, settlements and
         reasonable expenses actually incurred by any Indemnitee who was, is, or
         is threatened to be made a named defendant or respondent in any and all
         claims, demands, actions, suits or proceedings, civil, criminal,
         administrative or investigative, in which the Indemnitee may be
         involved, or threatened to be involved, as a party or otherwise, by
         reason of its status as (x) the General Partner or an affiliate thereof
         or (y) an officer, director, employee or agent of the Partnership,
         General Partner or an affiliate thereof, if the Indemnitee acted in
         good faith and in a manner it reasonably believed to be in, or not
         opposed to, the best interest of the Partnership. The termination of
         any action, suit or proceeding by judgment, order, settlement or
         conviction, or upon a plea of nolo contendere, or its equivalent, shall
         not, of itself, create a presumption that the Indemnitee acted in a
         manner contrary to that specified above.

                  b. The Partnership through the General Partner, in its sole
         discretion, may purchase and maintain insurance on behalf of the
         General Partner and such other persons as the General Partner shall
         determine, in its sole discretion, against any liability that may be
         asserted against or expense that may be incurred by such person in
         connection with the Partnership's activities, regardless of whether the
         Partnership would have the power to indemnify such person against such
         liability under the provisions of this Partnership Agreement.

                  c. Expenses incurred by an Indemnitee in defending any claim,
         demand, action, suit or proceeding subject to this Section 13 may, from
         time to time, be advanced by the Partnership prior to the final
         disposition of such claim, demand, action, suit or proceeding (i) upon
         a written affirmation by the Indemnitee of its good faith belief that
         it has met the standard of conduct necessary for indemnification and
         (ii) upon receipt by the Partnership of any undertaking by or on behalf
         of the Indemnitee to repay such amount if it shall be determined that
         such Person is not entitled to be indemnified as authorized in this
         Section 13.

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                  d. The indemnification provided in this Section 13 is for the
         benefit of the Indemnitees and shall not be deemed to create any right
         to indemnification for any other persons.

         14. Certification of Partnership Interests. The partners of the
Partnership hereby specify, acknowledge and agree that all interests in the
Partnership are securities governed by Article 8 and all other provisions of the
Uniform Commercial Code as adopted and amended in the State of Texas (the
"UCC"), and pursuant to the terms of Section 8.103 of the UCC, such interests
shall be "securities" for all purposes under such Article 8 and under all other
provisions of the UCC, and that the ownership interest of a partner shall be
recognized by a form of Partnership Certificate attached hereto as Annex A
("Certificates"). Certificates shall be numbered and executed by the President
and Secretary of the General Partner and shall be entered into a membership
transfer register as they are issued, which register shall be maintained by the
Secretary of the General Partner. Upon surrender to the Secretary of the General
Partner of a certificate for Partnership interests duly endorsed or accompanied
by proper evidence of succession, assignment or authority to transfer, it shall
be the duty of the General Partner to issue a new certificate to the person
entitled thereto, cancel the old certificate and record the transaction upon its
books.

         15. Governing Law. This Agreement shall be governed by, and construed
under, the laws of the State of Texas, all rights and remedies being governed by
said laws.


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         IN WITNESS WHEREOF, the undersigned, intending to be bound hereby, have
duly executed this Agreement of Limited Partnership as of the 31st day of July,
2000.

                                                  GENERAL PARTNER:

                                                  GRANT PRIDECO HOLDING, LLC


                                                  By: /s/ PHILIP A. CHOYCE
                                                     ---------------------------
                                                     Philip A. Choyce
                                                     Vice President



                                                  LIMITED PARTNER:

                                                  GRANT PRIDECO USA, LLC


                                                  By: /s/ LINDA S. BUBACZ
                                                      --------------------------
                                                      Linda S. Bubacz
                                                      Vice President


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