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Exhibit 5.1

January 31, 2020
Archrock, Inc.
9807 Katy Freeway, Suite 100
Houston, TX 77024

        Re: Registration Statement on Form S-3

Ladies and Gentlemen:

        We have acted as special counsel to Archrock, Inc., a Delaware corporation (the "Company"), in connection with its filing on the date hereof with the Securities and Exchange Commission (the "Commission") of a registration statement on Form S-3 (as amended, the "Registration Statement"), including a base prospectus (the "Base Prospectus"), which provides that it will be supplemented by one or more prospectus supplements (each such prospectus supplement, together with the Base Prospectus, a "Prospectus"), under the Securities Act of 1933, as amended (the "Act"), relating to the registration of up to 21,656,683 shares of the Company's common stock, par value $0.01 per share, to be resold from time to time by certain selling stockholders of the Company (the "Common Stock").

        This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related applicable Prospectus, other than as expressly stated herein with respect to the issue of the Common Stock.

        As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware, and we express no opinion with respect to any other laws, or as to any matters of municipal law or the laws of any local agencies within any state.

        Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, the Common Stock has been duly authorized by all necessary corporate action of the Company and are validly issued, fully paid and nonassessable.

        This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Registration Statement and to the reference to our firm in the Prospectus under the heading "Legal Matters." We further consent to the incorporation by reference of this letter and consent into any registration statement or post-effective

amendment to the Registration Statement filed pursuant to Rule 462(b) under the Act with respect to the Common Stock. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.

Very truly yours,

/s/ Latham & Watkins LLP

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Exhibit 5.1