JOINT FILING AGREEMENT

   1

                             JOINT FILING AGREEMENT


         We, the signatories of the statement on Schedule 13D filed with respect
to the Common Stock of National-Oilwell, Inc., to which this Agreement is
attached, hereby agree that such statement is, and any amendments thereto filed
by any of us will be, filed on behalf of each of us pursuant to and in
accordance with the provisions of Rule 13d-1(k) of the Securities Exchange Act
of 1934.

                                    FIRST RESERVE FUND V, LIMITED 
                                    PARTNERSHIP

                                    By:  First Reserve Corporation,
                                             as General Partner



                                    By: /s/ Xxxxxx X. Xxxxxxx
                                       ---------------------------------
                                         Name:  Xxxxxx X. Xxxxxxx
                                         Title:  Managing Director





                                    FIRST RESERVE FUND V-2, LIMITED 
                                    PARTNERSHIP

                                    By:  First Reserve Corporation,
                                             as General Partner



                                    By: /s/ Xxxxxx X. Xxxxxxx
                                       ---------------------------------
                                         Name:  Xxxxxx X. Xxxxxxx
                                         Title:  Managing Director





                                    FIRST RESERVE FUND VI, LIMITED 
                                    PARTNERSHIP

                                    By:  First Reserve Corporation,
                                             as General Partner



                                    By: /s/ Xxxxxx X. Xxxxxxx
                                       ---------------------------------
                                         Name:  Xxxxxx X. Xxxxxxx
                                         Title:  Managing Director



   2

                                FIRST RESERVE FUND VII, LIMITED 
                                PARTNERSHIP


                                By: First Reserve GP VII, LP,
                                         as General Partner

                                    By: First Reserve Corporation,
                                             as General Partner



                                    By: /s/ Xxxxxx X. Xxxxxxx
                                       --------------------------------------
                                         Name:  Xxxxxx X. Xxxxxxx
                                         Title:  Managing Director





                                FIRST RESERVE FUND VIII, LP


                                By: First Reserve GP VIII, LP,
                                         as General Partner,

                                    By: First Reserve Corporation
                                             as General Partner




                                    By: /s/ Xxxxxx X. Xxxxxxx
                                       --------------------------------------
                                         Name:  Xxxxxx X. Xxxxxxx
                                         Title:  Managing Director




                                FIRST RESERVE GP VII, LP

                                By: First Reserve Corporation,
                                         as General Partner



                                    By: /s/ Xxxxxx X. Xxxxxxx
                                       --------------------------------------
                                         Name:  Xxxxxx X. Xxxxxxx
                                         Title:  Managing Director




   3




                                FIRST RESERVE GP VIII, LP

                                By:  First Reserve Corporation,
                                         as General Partner



                                By: /s/ Xxxxxx X. Xxxxxxx
                                   --------------------------------------
                                     Name:  Xxxxxx X. Xxxxxxx
                                     Title:  Managing Director



                                FIRST RESERVE CORPORATION



                                By: /s/ Xxxxxx X. Xxxxxxx
                                   --------------------------------------
                                     Name:  Xxxxxx X. Xxxxxxx
                                     Title:  Managing Director





                                XXXXXXX X. XXXXXXXX




                                By: /s/ Xxxxxxx X. Xxxxxxxx
                                   --------------------------------------
                                     Name:  Xxxxxxx X. Xxxxxxxx


                                XXXX X. XXXX




                                By: /s/ Xxxx X. Xxxx
                                   --------------------------------------
                                     Name:  Xxxx X. Xxxx