EXHIBIT 3.31


                          CERTIFICATE OF INCORPORATION

         GRANT PRIDECO MARINE PRODUCTS AND SERVICES INTERNATIONAL, INC.

         First: The name of the Corporation is Grant Prideco Marine Products and
Services International, Inc.

         Second: The address of the Corporation's registered office in the State
of Delaware is 615 Dupont Highway, Dover, Kent County, Delaware 19901. The name
of the Corporation's registered agent at such address is Capitol Services, Inc.

         Third: The nature of the business and purpose to be conducted or
promoted by 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
Delaware.

         Fourth: The total number of shares of stock that the Corporation shall
have authority to issue is One Thousand (1,000) shares of Common Stock, of the
par value of $1.00 per share.

         Fifth: The name of the incorporator is Philip A. Choyce, whose mailing
address is 1330 Post Oak, Suite 2700, Houston, Texas 77056.

         Sixth: The Corporation is to have perpetual existence.

         Seventh: Election of directors need not be by written ballot unless the
bylaws of the Corporation shall so provide.

         Eighth: All the powers of the Corporation, insofar as the same may be
lawfully vested by this Certificate of Incorporation in the Board of Directors
of the corporation, are hereby conferred upon the Board of Directors of the
Corporation.

         In furtherance and not in limitation of the foregoing provisions of
this Article Eighth, and for the purpose of the orderly management of the
business and the conduct of the affairs of the Corporation, the Board of
Directors of the Corporation shall have the power to adopt, amend or repeal from
time to time the by-laws of the Corporation, subject to the right of the
stockholders f the Corporation entitled to vote thereon to adopt, amend or
repeal bylaws of the Corporation.

         Ninth: 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 statute, and all rights conferred upon
stockholders herein are granted subject to this reservation.

         THE UNDERSIGNED, being the incorporator hereinbefore named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, does make this Certificate, hereby declaring and certifying
that this is my act and deed and the facts herein stated are true. Accordingly,
I have hereunto set my hand this 26th day of June, 2002


                                        ------------------------
                                           Philip A. Choyce