Exhibit 10.13

Amendment #1

     This First Amendment (the “Amendment”) to the Supply Agreement ( the
“Supply Agreement”) dated as of June 2, 2003 to be effective August 1, 2003
between Voestalpine Tubulars GmbH & Co KG and Grant Prideco, Inc. is entered on
this 30th day of November 2003 to be made effective the 1st day of October, 2003
(effective for purchase orders placed on or after October 1, 2003).

WHEREAS, the parties entered into the above referenced Supply Agreement; and

WHEREAS, the parties now desire to amend paragraphs 4.1, 4.3 and 6.2 of the
Supply Agreement as follows.

NOW THEREFORE, for good and valuable consideration, which is hereby
acknowledged, the parties agree to amend the Supply Agreement as follows:

  1.   Paragraph 4.1 (sentence on line 11 and 12 only): The sentence on line 11
and 12 of Paragraph 4.1 of the Supply Agreement shall be replaced in full with
the following sentence:

“The Purchase Price is calculated on the basis of DES Houston full liner terms
in accordance with Incoterms 2000.”

  2.   Paragraph 4.3: Paragraph 4.3 of the Supply Agreement shall be replaced in
full with the following paragraph 4.3:

“4.3 Invoices will be submitted by Seller to Purchaser. Invoices will reference
Purchaser’s purchase order number and will contain such other information as
Purchaser may reasonably request. Purchaser shall effect payment within sixty
(60) calendar days after notice of readiness (or delivery order). Purchaser
shall pay interest on overdue invoice payments that are not contested as
provided in Section 3.3 from the due date up to the actual date of payment at
the rate determined to be three percent (3%) per annum above the six months
EURIBOR.”

  3.   Paragraph 6.2: Paragraph 6.2 of the Supply Agreement shall be replaced in
full with the following paragraph 6.2:

“6.2 Delivery is DES Houston full liner terms in accordance with Incoterms 2000.
Purchaser may also request, as specified in any particular purchase order, that
the delivery destination of the Material be a location other than Houston, for
the calculation for the Purchase Price, Section 4.1 of this Supply Agreement
shall apply.”

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     This amendment #1 is signed to be made effective October 1, 2003.

Voestalpine Tubulars GmbH & Co KG

             
By
  /s/ Hubert Wastl       /s/ Hillka Witt

           

  Hubert Wastl       Hilkka Witt

      Managing Directors    

          Grant Prideco, Inc.    
 
       
By
  /s/ Dan Latham    

 

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  Dan Latham, President    

  Drilling Products & Services    

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