Exhibit 3.21


                      CERTIFICATE OF LIMITED PARTNERSHIP

                                      OF

                           INTERNATIONAL FUELS, L.P.


          This Certificate of Limited Partnership of International Fuels, L.P.
(the "Partnership") is being executed and filed by the undersigned General
Partner (the "General Partner") to form a limited partnership under the Texas
Revised Limited Partnership Act (the "Act").

          1.  The name of the limited partnership is International Fuels, L.P.

          2.  The address of the registered office of the Partnership is 350
     North St. Paul Street, Dallas, Texas 75201, and the name and address of the
     registered agent for service of process on the Partnership required to be
     maintained by Section 1.06 of the Act are CT Corporation System, 350 North
     St. Paul Street, Dallas, Texas 75201.

          3.  The address of the principal office in the United States where
     records are required to be kept or made available under Section 1.07 of the
     Act is 3040 Post Oak Boulevard, Houston, Texas 77056.

          4.   The name of the General Partner is Eurofuels LLC, and the mailing
     address of its business is 3040 Post Oak Boulevard, Houston, Texas 77056.

          IN WITNESS WHEREOF, the undersigned has executed this Certificate as
of the 15th day of August, 2000.


                                     GENERAL PARTNER:

                                      EUROFUELS LLC,
                                      a Delaware limited liability company,



                                      By     /s/ J. Nathan  Hubbard
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                                      Name:      J. Nathan  Hubbard
                                            ------------------------------------
                                      Title:     Vice President and Manager
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