<PAGE>   1
                                                                   EXHIBIT 10.29

                       FIRST AMENDMENT TO CREDIT AGREEMENT

         This FIRST AMENDMENT TO CREDIT AGREEMENT, dated as of September __
1999, is hereby made and entered into by and between BAKER HUGHES INCORPORATED,
a Delaware corporation (the "Company"), and the undersigned bank (the "Bank").

                                   WITNESSETH

         WHEREAS, the Company and the Bank have entered into that certain Credit
Agreement dated as of October 1, 1998 with an initial term of 364 days (the
"Credit Agreement"); and

         WHEREAS, the Company and the Bank desire to amend the Credit Agreement
as hereinafter set forth.

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained, the Company and the Bank agree as follows:

     1. AMENDMENTS TO CREDIT AGREEMENT.

          (a) Section 1.01 (Definitions) of the Credit Agreement is amended as
              follows:

              (i) The words "or the most recent amendment to this agreement" are
              inserted between the words "Agreement" and "as" in the second line
              of the definition of "Commitment Limit."

              (ii) The following phrase is added at the end of the definition of
              "LIBOR Margin":

                   "; provided, further, that, in the event that the aggregate
                   Eurodollar Advances and Reference Rate Advances outstanding
                   exceed thirty-three and one-third percent (331/3%) of the
                   Commitment Limit, then the Eurodollar Rates in (a), (b) and
                   (c) above shall be increased to .245%, .35% and .52%,
                   respectively, for all Eurodollar Advances outstanding during
                   the period in which the aggregate Eurodollar Advances and
                   Reference Rate Advances outstanding exceed thirty-three and
                   one-third percent (331/3%) of the Commitment Limit."

          (b) Section 2.04 (Facility and Origination Fees) of the Credit
              Agreement is amended by adding the following subsection (c):

                   "(c) Up-Front Fee. If the Bank consents to the Company's
                   Extension Request pursuant to Section 3.01(h), then the
                   Company



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                                                                   EXHIBIT 10.29

                   agrees to pay the Bank a one-time fee, in Dollars, equal to
                   .03% of the Commitment Limit, payable no later than October
                   15, 1999."

          (c) Exhibit B (Bank and Other Banks) to the Credit Agreement is
              amended in its entirety and replaced with a new Exhibit B as
              attached hereto.

     2. REPRESENTATIONS AND WARRANTIES OF THE COMPANY. The Company's execution,
        delivery and performance of this Amendment have been duly authorized by
        all necessary corporate action, do not require the consent or approval
        of any governmental body or other regulatory authority, and are not in
        contravention of or in conflict with any law or regulation applicable to
        the Company or any term or provision of the charter or bylaws of the
        Company. This Amendment is the valid and legally binding obligation of
        the Company, enforceable in accordance with its terms, except as such
        enforceability may be

              (i) limited by the effect of any applicable bankruptcy,
              insolvency, reorganization, moratorium, fraudulent transfer or
              other similar laws from time to time in effect and judicial
              decisions relating to or affecting the enforceability of
              creditors' rights and debtor's obligations generally, and

              (ii) subject to the effect of general principles of equity
              (regardless of whether such enforceability is considered in a
              proceeding in equity or at law).

     3. REAFFIRMATION OF CREDIT AGREEMENT. This Amendment shall be deemed to be
        an amendment to the Credit Agreement, and the Credit Agreement, as
        amended hereby, is hereby ratified, approved and confirmed in each and
        every respect. All references to the Credit Agreement in the Credit
        Agreement shall hereafter be deemed to refer to the Credit Agreement, as
        amended hereby.

     4. DEFINED TERMS. Terms used but not defined herein when defined in the
        Credit Agreement shall have the same meanings herein unless the context
        otherwise requires.

     5. APPLICABLE LAW. This Amendment shall be governed by and construed in
        accordance with the laws of the State of Texas, United States of
        America.

     6. COUNTERPARTS. This Amendment may be separately executed (including
        execution by delivery of a facsimile or telecopied signature) in any
        number of counterparts and by different parties hereto in separate



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                                                                   EXHIBIT 10.29

        counterparts, each of which when so executed shall be deemed to
        constitute one and the same Amendment.

     7. SEVERABILITY. If any term or provision of this Amendment shall be
        determined to be illegal or unenforceable, all other terms and
        provisions of those documents shall nevertheless remain effective and
        shall be enforced to the fullest extent permitted by applicable law.

     8. HEADINGS. Section headings used in this Amendment are for reference only
        and shall not affect the construction of this Amendment.

     9. FINAL AGREEMENT. THIS AMENDMENT, TOGETHER WITH THE CREDIT AGREEMENT,
        REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE
        CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL
        AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS
        BETWEEN THE PARTIES.



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                                                                   EXHIBIT 10.29

         IN WITNESS WHEREOF, the Company and the Bank have caused this First
Amendment to Credit Agreement to be duly executed as of the day and year first
above written.

COMPANY:
BAKER HUGHES INCORPORATED



By:
   ---------------------------------
       H. Gene Shiels
       Assistant Treasurer


BANK:



By:
   ---------------------------------
Name:
Title:


Commitment Limit:
(if different than limit on signature page to Credit Agreement)



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                                                                   EXHIBIT 10.29

                                    EXHIBIT B
                              BANK AND OTHER BANKS


<TABLE>
<CAPTION>
Bank and Other Banks                                                Commitment Limit
--------------------                                                ----------------
<S>                                                                 <C>
ABN AMRO Bank N.V.                                                    12,500,000
Australia and New Zealand Banking Group Limited                       12,500,000
Bank of America National Trust and Savings Association                28,125,000
Bank of Tokyo-Mitsubishi, Ltd.                                        12,500,000
The Bank of New York                                                  12,500,000
Barclays Bank PLC                                                     25,000,000
Bayerische Hypo- Und Vereinsbank AG                                   12,500,000
Chase Bank of Texas, National Association                             28,125,000
Citibank, NA                                                          28,125,000
Credit Suisse First Boston                                            12,500,000
Dresdner Bank AG, New York Branch                                     12,500,000
Morgan Guaranty Trust Company of New York                             28,125,000
Northern Trust Company                                                12,500,000
Royal Bank of Canada                                                  12,500,000
                                                                     -----------

         TOTAL                                                       250,000,000
</TABLE>



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