Sec Form 4 Filing - ARCLIGHT ENERGY PARTNERS FUND V, L.P. @ American Midstream Partners, LP - 2018-08-15

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ARCLIGHT ENERGY PARTNERS FUND V, L.P. 2. Issuer Name and Ticker or Trading Symbol American Midstream Partners, LP [ AMID] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) X __ Other (specify below) SEE REMARKS (Last) (First) (Middle) C/O ARCLIGHT CAPITAL PARTNERS, LLC, 200 CLARENDON STREET, 55TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 08/15/2018 (Street) BOSTON, MA02117 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Units (limited partner interests) 08/15/2018 P 595,228 A $ 6.16 ( 1 ) 14,572,937 ( 2 ) I (3) ( 3 ) Common Units (limited partner interests) 08/15/2018 P 2,500 A $ 6.25 14,575,437 ( 2 ) I (4) ( 4 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ARCLIGHT ENERGY PARTNERS FUND V, L.P. C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X SEE REMARKS ArcLight Capital Holdings, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X ArcLight Capital Partners, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X Revers Daniel R C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X Signatures /s/ Daniel S. ReversFUND VBy: ArcLight PEF GP V, LLC, its General PartnerBy: ArcLight Capital Holdings, LLC, its ManagerBy: ACHP II, L.P., its Managing MemberBy: ACH GP, LLC, its General PartnerBy: Daniel R. Revers, Manager 08/17/2018 Signature of Reporting Person Date /s/ Daniel S. ReversARCLIGHT CAPITAL HOLDINGS, LLCBy: ACHP II, L.P., its Managing MemberBy: ACH GP, LLC, its General PartnerBy: Daniel Revers, Manager 08/15/2018 Signature of Reporting Person Date /s/ Daniel S. ReversARCLIGHT CAPITAL PARTNERS, LLCBy: Daniel R. Revers, Managing Partner 08/15/2018 Signature of Reporting Person Date /s/ Daniel S. Revers 08/17/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The price reported in Column 4 is a weighted average price. These common units were purchased in multiple transaction ranging from $5.80 to $6.50, inclusive. The Reporting Persons undertake to provide to American Midstream Partners, LP (the "Issuer"), any security holder of the Issuer or the staff of the United States Securities and Exchange Commission, upon request, full information regarding the number of common units purchased at each separate price within the ranges set forth above. ( 2 )Does not include (i) 7,707,571 Series A-1 Convertible Preferred Units held directly by High Point Infrastructure Partners, LLC ("HPIP"), which have no expiration date and are convertible in whole or in part into common units of the Issuer at a conversion rate of 1:1.1582 at any time, (ii) 3,302,158 Series A-2 Convertible Preferred Units held by Magnolia Infrastructure Partners, LLC ("Magnolia"), which have no expiration date and are convertible in whole or in part into common units of the Issuer at a conversion rate of 1:1.1582 at any time and (iii) 9,241,642 Series C Convertible Preferred Units held by Magnolia Infrastructure Holdings, LLC ("Magnolia Holdings"), which have no expiration date and are convertible in whole or in part into common units of the Issuer at a conversion rate of 1:1.0542 at any time. ( 3 )The common units reflected in Column 5 include (i) 2,850,982 common units directly owned by Busbar II, LLC ("Busbar"), (ii) 9,753,425 common units directly owned by Magnolia Holdings, (iii) 618,921 common units directly owned by Magnolia and (iv) 1,349,609 common units directly owned by American Midstream GP, LLC (the "General Partner"), the general partner of the Issuer. ( 4 )The common units reflected in Column 5 include (i) 2,853,482 common units directly owned by Busbar, (ii) 9,753,425 common units directly owned by Magnolia Holdings, (iii) 618,921 common units directly owned by Magnolia and (iv) 1,349,609 common units directly owned by the General Partner.

Remarks: ArcLight Capital Holdings, LLC ("ArcLight Holdings") is the sole manager and member of ArcLight Capital Partners, LLC ("ArcLight Partners" and, together with ArcLight Holdings and ArcLight Energy Partners Fund V, L.P. ("Fund V"), the "ArcLight Entities"). ArcLight Partners is the investment adviser to Fund V. ArcLight Holdings is the manager of the general partner of Fund V. Mr. Revers is a manager of the general partner of the limited partnership that manages ArcLight Holdings, a managing partner of ArcLight Partners and has certain voting and dispositive rights as a member of ArcLight Partners' investment committee. Fund V directly owns Busbar and Magnolia Holdings, which owns Magnolia. Fund V, through Magnolia, also owns approximately 90% of the ownership interest in HPIP. HPIP and AMID GP Holdings LLC, a subsidiary of Magnolia Holdings, own respectively, approximately 77% and 23% of the General Partner. As a result, the ArcLight Entities and Mr. Revers may be deemed to indirectly beneficially own the securities of the Issuer held by Magnolia Holdings, Busbar, Magnolia, HPIP and the General Partner, but disclaim beneficial ownership except to the extent of their respective pecuniary interests therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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