Exhibit 23.1 

Consent of Independent Registered Public Accounting Firm 

We consent to the incorporation by reference in the following Registration Statements: 

●  Registration Statement (Form S-3 No. 333-187034) of MRC Global Inc.; 

●  Registration Statement (Form S-3 No. 333-206456) of MRC Global Inc.; 

●  Registration Statement (Form S-3 No. 333-226883) of MRC Global Inc.;  

●  Registration Statement (Form S-8 No. 333-180777) pertaining to the MCJ Holding Corporation 2007 Stock Option Plan and MRC Global Inc. 2011 Omnibus Incentive Plan; 

●  Registration Statement (Form S-8 No. 333-206455) pertaining to the MRC Global Inc. 2011 Omnibus Incentive Plan, as amended, and related prospectus; and 

●  Registration Statement (Form S-8 No. 333-231222) pertaining to the MRC Global Inc. 2011 Omnibus Incentive Plan, as amended, and related prospectus 

of our reports dated February 12, 2021, with respect to the consolidated financial statements and effectiveness of internal control over financial reporting of MRC Global Inc. included in this Annual Report (Form 10-K) of MRC Global Inc. for the year ended December 31, 2020.

/s/ Ernst & Young LLP

Houston, Texas 

February 12, 2021