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                                                                    EXHIBIT 10.1

                               FOURTH AMENDMENT TO
                   SECOND AMENDED AND RESTATED LOAN AGREEMENT


                  THIS FOURTH AMENDMENT TO SECOND AMENDED AND RESTATED LOAN
AGREEMENT (this "Fourth Amendment" or this "Amendment") dated effective as of
July 31, 2002 is entered into by and among HYDRIL COMPANY, a Delaware
corporation ("Borrower"), the banks listed on the signature pages hereof (along
with any other Person who becomes a lender, the "Lenders"), the guarantors
listed on the signature page hereto and any Person who becomes a Guarantor
subsequent hereto (collectively the "Guarantors"), and BANK ONE, NA,
successor-in-interest to Bank One, Texas, N.A., with its main office in Chicago,
Illinois ("Bank One"), individually as a Lender and as agent for Lenders (in
such capacity, the "Agent").



                              PRELIMINARY STATEMENT

                  WHEREAS, Borrower and Bank One, as the Agent and as a Lender,
entered into that certain Second Amended and Restated Loan Agreement dated
August 25, 2000 (the "Original Loan Agreement") under the terms of which Lenders
agreed to make revolving credit loans to Borrower not to exceed $25,000,000; and

                  WHEREAS, Borrower and Bank One, as the Agent and as a Lender,
entered into that certain First Amendment to Second Amended and Restated Loan
Agreement dated September 29, 2000 (the "First Amendment") pursuant to which
Borrower and Lenders agreed to amend certain terms and provisions of the
Original Loan Agreement; and

                  WHEREAS, Borrower and Bank One, as the Agent and as a Lender,
entered into that certain Second Amendment to Second Amended and Restated Loan
Agreement dated September 25, 2001 (the "Second Amendment") pursuant to which
Borrower and Lenders agreed to further amend certain terms and provisions of the
Original Loan Agreement, as amended by the First Amendment; and

                  WHEREAS, Borrower and Bank One, as the Agent and as a Lender,
entered into that certain Third Amendment to Second Amended and Restated Loan
Agreement dated December 19, 2001 (the "Third Amendment") pursuant to which
Borrower and Lenders agreed to further amend certain terms and provisions of the
Original Loan Agreement, as amended by the First Amendment and the Second
Amendment (the Original Loan Agreement, as amended by the First Amendment, the
Second Amendment and the Third Amendment, is hereinafter referred to as the
"Loan Agreement"); and

                  WHEREAS, Guarantors have executed that certain Guaranty dated
December 19, 2001 (the "Guaranty Agreement") guaranteeing, among other things,
the Obligations (as such term is defined in the Guaranty Agreement) of Borrower
under the Loan Agreement; and

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                  WHEREAS, Borrower has now requested that the Agent and Lenders
modify the Loan Agreement further and change certain terms thereof, and the
Agent and Lenders have agreed to do so; and

                  WHEREAS, Lenders, the Agent, Borrower and Guarantors wish to
execute this Amendment to evidence such agreement;

                  NOW, THEREFORE, in consideration of the premises and the
mutual covenants herein contained and for other good and valuable consideration,
the receipt and adequacy of which are hereby acknowledged, Borrower, Guarantors,
Lenders and the Agent hereby agree as follows (all capitalized terms used herein
and not otherwise defined shall have the meanings as defined in the Loan
Agreement):

                  Section 1. Amendment to Section 1.1. Section 1.1 of the Loan
Agreement is hereby amended by deleting the definition of "Revolving Loan
Commitment" in its entirety and substituting in its place the following:

                  "Revolving Loan Commitment means $5,000,000.00."

                  Section 2. Representations True; No Default. Borrower
represents and warrants that:

                     (i) this Amendment has been duly authorized, executed and
              delivered on its behalf; the Loan Agreement, as amended hereby,
              together with the Notes and the other Loan Documents to which
              Borrower is a party, constitute valid and legally binding
              agreements of Borrower enforceable in accordance with their terms,
              except as enforceability thereof may be limited by bankruptcy,
              insolvency, fraudulent conveyance, fraudulent transfer,
              reorganization or moratorium or other similar law relating to
              creditors' rights and by general equitable principles which may
              limit the right to obtain equitable remedies (regardless of
              whether such enforceability is considered in a proceeding, in
              equity or at law);

                     (ii) the representations and warranties of Borrower
              contained in Article 6 of the Loan Agreement are true and correct
              in all material respects on and as of the date hereof as though
              made on and as of the date hereof, except to the extent such
              representations and warranties relate solely to an earlier date or
              are untrue as a result of transactions permitted under the Loan
              Agreement as amended hereby;

                     (iii) after giving effect to this Amendment, no Default or
              Event of Default under the Loan Agreement has occurred and is
              continuing;

                     (iv) Exhibit 6.9 to the Loan Agreement is true and correct
              as of the date hereof; and

                     (v) The execution of this Amendment and the guaranties
              contemplated herein will not result in a breach of any provision
              of the Note Agreement and no consent or agreement of the
              Noteholders is required to be obtained in connection with the
              execution of this Amendment or the guaranties contemplated herein.


                                       2
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                  Section 3. Expenses, Additional Information. Borrower shall
pay to the Agent all reasonable expenses incurred in connection with the
execution of this Amendment, including all reasonable expenses incurred in
connection with any previous negotiation and loan documentation. Borrower shall
furnish to the Agent and Lenders all such other documents, consents and
information relating to Borrower as the Agent or any Lender may reasonably
require to accomplish the purposes hereof.

                  Section 4. Effectiveness. This Amendment shall become
effective when, and only when Borrower, Guarantors, Lenders and the Agent shall
have executed and delivered to the Agent a counterpart of this Amendment.

                  Section 5. Miscellaneous Provisions.

                  (a) From and after the execution and delivery of this
Amendment, the Loan Agreement shall be deemed to be amended and modified as
herein provided, and except as so amended and modified the Loan Agreement shall
continue in full force and effect.

                  (b) The Loan Agreement and this Amendment shall be read and
construed as one and the same instrument.

                  (c) Any reference in any Loan Document to the Loan Agreement
shall be a reference to the Loan Agreement as amended by this Amendment.

                  (d) THIS AMENDMENT SHALL BE CONSTRUED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF THE STATE OF TEXAS AND OF THE UNITED STATES OF AMERICA.

                  (e) This Amendment may be signed in any number of counterparts
and by different parties in separate counterparts and may be in original or
facsimile form, each of which shall be deemed an original but all of which
together shall constitute one and the same instrument.

                  (f) The headings herein shall be accorded no significance in
interpreting this Amendment.

                  Section 6. Guarantors. This Amendment does not have the effect
of discharging, releasing or in any way modifying or limiting the obligations of
the Guarantors under the Guaranty Agreement, which is, and shall remain, in full
force and effect. Guarantors, by execution below, hereby consent to this
Amendment and the modification to the Loan Agreement described herein and
acknowledge and agree that their respective obligations under the Guaranty
Agreement are not affected hereby and that such obligations are continuing,
existing and in full force and effect.

                  Section 7. Binding Effect. This Amendment shall be binding
upon and inure to the benefit of Borrower, Lenders and the Agent and their
respective successors and assigns, except that Borrower shall not have the right
to assign its rights hereunder or any interest herein.

                  SECTION 8. FINAL AGREEMENT OF THE PARTIES. THIS AMENDMENT, THE
NOTES, THE LOAN AGREEMENT AND THE OTHER LOAN DOCUMENTS


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CONSTITUTE A "LOAN AGREEMENT" AS DEFINED IN SECTION 26.02(a) OF THE TEXAS
BUSINESS AND COMMERCE CODE AND REPRESENT 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.

                  Section 9. This Amendment may be executed by the parties on
separate counterparts, and each counterpart when so executed and delivered shall
constitute an original instrument, and all such separate counterparts shall
constitute but one and the same instrument.

             [The remainder of this page intentionally left blank.]


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                  IN WITNESS WHEREOF, the parties have caused this Amendment to
be executed by their respective duly authorized officers to be effective as of
the date first written above.

                                 BORROWER:

                                        HYDRIL COMPANY


                                        By: /s/ Michael C. Kearney
                                           -------------------------------------
                                        Name:   Michael C. Kearney
                                        Title:  Chief Financial Officer &
                                                Vice President Administration


                                        By: /s/ Andrew W. Ricks
                                           -------------------------------------
                                        Name:   Andrew W. Ricks
                                        Title:  Treasurer


                                 AGENT/BANK:

                                        BANK ONE, NA, Individually, as a
                                        Lender and as the Agent


                                        By: /s/  Brandi Molaison
                                           -------------------------------------
                                        Name:    Brandi Molaison
                                        Title:   Vice President


                  [First Signature Page to Fourth Amendment to
                  Second Amended and Restated Credit Agreement]

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                                   GUARANTORS:

                                   HYDRIL COMPANY LP

                                   By:        Hydril General LLC,
                                              its General Partner

                                              By: /s/ Christopher T. Seaver
                                                  ------------------------------
                                              Name:   Christopher T. Seaver
                                              Title:  President


                                   HYDRIL GENERAL LLC


                                   By: /s/ Christopher T. Seaver
                                       -----------------------------------------
                                   Name:   Christopher T. Seaver
                                   Title:  President


                                   HYDRIL LIMITED LLC


                                   By: /s/ Toni L. Lindsay
                                       -----------------------------------------
                                   Name:   Toni L. Lindsay
                                   Title:  Assistant Secretary

                  [Second Signature Page to Fourth Amendment to
                  Second Amended and Restated Credit Agreement]