LIMITED POWER OF ATTORNEY

      The undersigned, being an executive officer of MRC Global Inc. (the
"Corporation"), who will hereby be subject to the reporting obligations of
Section 16 of the Securities Exchange Act of 1934, as amended (the "Act"), with
respect to securities of the Corporation, hereby constitutes and appoints, with
full power of substitution or revocation, each of Daniel J. Churay and Ann D.
Garnett, or such attorneys'-in-fact substitute or substitutes, as the
undersigned's true and lawful attorneys-in-fact and agents to execute and file
for and on behalf of the undersigned Forms 3, 4 and 5 with the Securities and
Exchange Commission (the "SEC"), and to perform all acts necessary in order to
execute and file such Forms 3, 4 and 5, as he or she, as applicable, shall deem
appropriate.  The undersigned hereby ratifies and confirms all that said
attorneys-in-fact and agents, or such attorneys'-in-fact substitute or
substitutes, shall do or cause to be done by virtue hereof.

      The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, or such
attorneys'-in-fact substitute or substitutes, are not assuming, nor is the
Corporation assuming, any of the undersigned's responsibilities to comply with
Section 16 of the Act.  This Limited Power of Attorney shall remain in full
force and effect until the undersigned is no longer required to file Forms 3, 4
and 5 with respect to the undersigned's holdings of and transactions in
securities issued by the Corporation, unless earlier revoked by the undersigned
in a signed writing delivered to the foregoing attorneys-in-fact.

      This Limited Power of Attorney is effective as of April 1, 2016, and any
previous power of attorney issued by the undersigned for the purpose of
executing and filing Forms 3, 4 and 5 with the SEC with respect to holdings of
and transactions in securities issued by the Corporation is hereby revoked
(without affecting the effectiveness of any such power of attorney prior to the
date hereof).



                                                  /s/ Robert Stein
                                                  ------------------------------
                                                  Robert Stein