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                                                                     EXHIBIT 5.1


                             [FLOWSERVE LETTERHEAD]


June 25, 1999



Flowserve Corporation
222 W. Las Colinas Boulevard
Suite 1500
Irving, Texas 75039

Dear Sirs:

With reference to the registration statement on Form S-8 which Flowserve
Corporation (the "Company") proposes to file with the Securities and Exchange
Commission (the "SEC") under the Securities Act of 1933, registering 675,000
shares of common stock, par value $1.25 per share, of the Company (the "Shares")
under the Charles C. Hall Profit Sharing Retirement Plan (the "Plan"), I am of
the opinion that:

1.   the Company is a corporation duly organized, validly existing and in good
     standing under the laws of the State of New York, and

2.   all proper corporate proceedings have been taken so that any Shares to be
     offered and sold which are of original issuance, upon sale and payment
     therefor in accordance with the Plan and the resolutions of the Board of
     Directors relating to the offering and sale of the Shares thereunder, will
     be legally issued, fully paid and nonassessable.

I hereby consent to the filing of this opinion with the SEC in connection with
the registration statement referred to above.


                                        Very truly yours,

                                        /s/ RONALD F. SHUFF
                                        ----------------------------
                                        Ronald F. Shuff
                                        Vice President, Secretary &
                                        General Counsel