EXHIBIT 3.1

                         CERTIFICATE OF INCORPORATION OF
                             CHANDLER (U.S.A.), INC.


         1. The name of the corporation is: Chandler (U.S.A.), Inc.

         2. The address of the registered office of the corporation is: 1006
Manvel, Chandler, OK 74834 and the name of its registered agent at such address
is: Mark T. Paden

         3. The purpose of the corporation is to engage in any lawful act or
activity for which corporations may be organized under the general corporation
law of the State of Oklahoma.

         4. The duration of the corporation is: Perpetual

         5. The name and mailing address of each incorporator is as follows:

         NAME:                                  ADDRESS:
         -----                                  --------

         R. Patrick Gilmore                     P.O. Box 686
                                                Stroud, OK 74079

         6. The total number of shares of stock which the corporation shall have
authority to issue is: 50,000 shares, each of the shares having a par value of $
1.00, thereby resulting in the corporation having total authorized capital stock
in the amount of $ 50,000.00, all of which shall be common stock.

         7. The board of directors of the corporation shall have full authority,
to the extent permitted by law, to increase, decrease, or otherwise adjust the
capital stock of the corporation, to designate the classes or series thereof and
to determine whether all or any part of such stock shall have voting powers,
full or limited, or no voting powers, and to determine such designations, and
such powers, preferences, relative, participating or optional, or other special
rights and the qualifications, limitations or restrictions thereof as the board
shall from time to time determine in duly adopted resolutions.

         At any time and from time to time when authorized by resolution of the
board of directors and without any action by shareholders, the corporation may
issue or sell any shares of its capital stock of any class or series, whether
out of the unissued shares thereof authorized by the Certificate of
Incorporation of the corporation as originally filed or by an amendment thereof
or out of shares of its capital stock acquired by it after the issue thereof,
and whether or not the shares thereof so issued or sold shall confer upon the
holders thereof the right to exchange or convert such shares for or into other
shares of capital stock of the corporation of any class or classes or any series
thereof. When similarly authorized, but without any action by its shareholders,
the corporation may issue or grant rights, warrants or options, in bearer or
registered or such other form as the board of directors







may determine, for the purchase of shares of the capital stock of any class or
series of the corporation within such period of time, or without limit as to
time, to such aggregate number of shares, and at such price per share, as the
board of directors may determine. Such rights, warrants, or options may be
issued or granted separately or in connection with the issue of any bonds,
debentures, notes, obligations or other evidences of indebtedness or shares of
the capital stock of any class or series of the corporation and for such
consideration and on such terms and conditions as the board of directors in its
sole discretion may determine. In each case, the consideration to be received by
the corporation for any such share so issued or sold shall be such as shall be
fixed from time to time by resolution of the board of directors.

         8. In furtherance and not in limitation of the powers conferred by
statute, the board of directors is expressly authorized:

            (a)  To adopt, amend or repeal the by-laws of the corporation.

            (b)  To authorize and cause to be executed or granted
            mortgages, security interests and liens upon the real and
            personal property of the corporation.

            (c)  To set apart out of any of the funds of the corporation
            available for dividends a reserve or reserves for any proper
            purpose and to abolish any such reserve in the manner in which
            it was created.

            (d)  By a majority of the whole board of directors, to
            designate one or more committees, each committee to consist of
            one (1) or more of the directors of the corporation. The board
            may designate one (1) or more directors as alternate members
            of any committee, who may replace any absent or disqualified
            member at any meeting of the committee. Any such committee, to
            the extent provided in the resolution or in the by-laws of the
            corporation, shall have and may exercise the powers of the
            board of directors in the management of the business and
            affairs of the corporation, and may authorize the seal of the
            corporation to be affixed to all papers which may require it;
            provided, however, the by-laws may provide that in the absence
            or disqualification of any member of such committee or
            committees, the member or members thereof present at any
            meeting and not disqualified from voting, whether or not he or
            they constitute a quorum, may unanimously appoint another
            member of the board of directors to act at the meeting in the
            place of any such absent or disqualified member.

            (e)  When and as authorized by the affirmative vote of the
            holders of a majority of the stock issued and outstanding
            having voting power given at a shareholders' meeting duly
            called upon such notice as is required by law, or when
            authorized by the written consent of the holders of a majority
            of the voting stock issued and outstanding, to sell, lease or
            exchange all or substantially all of the property and assets
            of the corporation, including its goodwill and its corporate
            franchises, upon

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            such terms and conditions and for such consideration, which
            may consist in whole or in part of money or property including
            shares of stock in, and/or other securities of, any other
            corporation or corporations, as its board of directors shall
            deem expedient and for the best interests of the corporation.

         9. Whenever a compromise or arrangement is proposed between this
corporation and its creditors or any class of them and/or between this
corporation and its shareholders or any class of them, any Court of equitable
jurisdiction within the State of Oklahoma, on the application in a summary way
of this corporation or of any creditor or shareholder thereof, or on the
application of any receiver or receivers appointed for this corporation under
the provisions of Section 1106 of Title 18 of the Oklahoma Statutes or on the
application of trustees in dissolution or of any receiver or receivers appointed
for this corporation under the provisions of Section 1100 of Title 18 of the
Oklahoma Statutes order a meeting of the creditors or class of creditors, and/or
of the shareholders or class of shareholders of this corporation, as the case
may be, to be summoned in such manner as the Court directs. If a majority in
number representing three-fourths (3/4) in value of the creditors or class of
creditors, and/or of the shareholders or class of shareholders of this
corporation, as the case may be, agree to any compromise or arrangement and to
any reorganization of this corporation as consequence of such compromise or
arrangement, the compromise or arrangement and the reorganization shall, if
sanctioned by the Court to which the application has been made, be binding on
all the creditors or class of creditors and/or on all the shareholders or class
of shareholders of this corporation, as the case may be, and also on this
corporation.

         10. Meetings of shareholders may be held within or without the State of
Oklahoma, as the by-laws may provide. The books of the corporation may be kept
(subject to applicable law) inside or outside the State of Oklahoma at such
place or places as may be designated from time to time by the board of directors
of the corporation. Elections of directors need not be by written ballot unless
the by-laws of the corporation shall so provide.

         11. To the extent permitted by law, no contract or transaction between
the corporation and one or more of its directors or officers, or between the
corporation and any other corporation, partnership, association or other
organization in which one or more of its directors or officers are directors or
officers or have a financial interest, shall be void or voidable solely for this
reason, or solely because the directors or officers are present at or
participate in the meeting of the board or committee thereof which authorizes
the contract or transaction, or solely because the directors or officers or
their votes are counted for such purpose.

         12. The board of directors is expressly authorized to indemnify any
person who was or is a party or is threatened to be made a party to any
threatened, pending or completed action, suit or proceeding whether civil,
criminal, administrative or investigative, other than an action by or in the
right of the corporation, by reason of the fact that such person is or was a
director, officer, employee or agent of the corporation or is or was serving at
the request of the corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise
against

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expenses, including attorney's fees, judgments, fines and amounts paid in
settlement to the extent and in the manner permitted by the laws of the State of
Oklahoma.

         13. In furtherance and not in limitation of the powers conferred by the
laws of the State of Oklahoma, the board of directors is expressly authorized to
adopt, amend or repeal the by-laws of the corporation.

         14. The corporation reserves the right to amend, alter, change or
repeal any provision contained in this Certificate of Incorporation, in the
manner now or hereafter prescribed by law, and all rights conferred upon the
shareholders herein are granted subject to this reservation.

         The Undersigned (whether one or more), being the incorporators)
hereinbefore named, for the purpose of forming a corporation pursuant to the
Oklahoma General Corporation Act, make(s) this Certificate, hereby declaring and
certifying that this is the act and deed of the undersigned and that the facts
herein stated are true, as of this 30th day June, 1988.


                                        /s/ R. Patrick Gilmore
                                        -------------------------------------


STATE OF OKLAHOMA   )
                    ) SS
COUNTY OF LINCOLN   )

         Before me a Notary Public in and for said County and State on this 30th
day of June, 1988, personally appeared R. Patrick Gilmore to me known to be the
identical person who executed the foregoing Articles of Incorporation and
acknowledge to me that he executed the same as his free and voluntary act and
deed for the uses and purposes therein set forth.

         IN WITNESS WHEREOF, I have hereunto set my hand and seal the day and
year above written.

My Comm. Expires:                       /s/ Joyce Seitz
                                        -------------------------------------
                                        Notary Public
December 1, 1990
- ----------------------------
(SEAL)

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