UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 29)*

American Midstream Partners, LP

(Name of Issuer)

Common Units Representing Limited Partner Interests

(Title of Class of Securities)

02752P 100

(CUSIP Number)

Christine Miller

Magnolia Infrastructure Partners, LLC

c/o ArcLight Capital Partners

200 Clarendon Street, 55th Floor

Boston, MA 02117

(617) 531-6338

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

May 13, 2019

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), Rule 13d-1(f) or Rule 13d-1(g), check the following box: ☐

*	The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person American Midstream GP, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 1,349,609 common units of the Issuer (“Common Units”) held by American Midstream GP, LLC, the Issuer’s general partner (the “General Partner”) and 8,180,101 Series A-l Convertible Preferred Units (“Series A-l Units”) convertible into 10,479,528 Common Units held by the General Partner.

Note 2: Based on 64,930,834 Common Units outstanding, which equals the sum of (a) 54,451,306 Common Units outstanding as of May 3, 2019 and (b) 10,479,528 Common Units issuable upon the conversion of Series A-l Units outstanding.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person AMID GP Holdings, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 1,349,609 common units of the Issuer (“Common Units”) held by American Midstream GP, LLC, which is approximately 14% owned by AMID GP Holdings, LLC (the “General Partner”) and 8,180,101 Series A-l Convertible Preferred Units (“Series A-l Units”) convertible into 10,479,528 Common Units held by the General Partner.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person High Point Infrastructure Partners, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 1,349,609 common units of the Issuer (“Common Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC and 8,180,101 Series A-l Convertible Preferred Units (“Series A-l Units”) convertible into 10,479,528 Common Units held by the General Partner.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person Magnolia Infrastructure Partners, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-1 Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and 618,921 Common Units held by Magnolia.

Note 2: Based on 69,420,582 Common Units outstanding, on an as-converted basis, which equals the sum of (a) 54,451,306 Common Units outstanding as of May 3, 2019, (b) 10,479,528 Common Units issuable upon the conversion of Series A-l Units outstanding and (c) 4,489,748 Common Units issuable upon the conversion of Series A-2 Units outstanding.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person JP Energy Development, L.P.
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 422,805 common units of the Issuer (“Common Units”) held by JP Energy Development, L.P.

Note 2: Based on 54,451,306 Common Units outstanding as of May 3, 2019.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person Magnolia Infrastructure Holdings, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-l Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 9,795,064 Series C Convertible Preferred Units (“Series C Units”) held by Magnolia Infrastructure Holdings, LLC (“Magnolia Holdings”), convertible into 9,808,777 Common Units, 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016, 10,141,137 Common Units held by Magnolia Holdings, 422,805 Common Units held by JP Energy Development, L.P., 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and approximately 14% owned by AMID GP Holdings, LLC, which is approximately 93% owned by Magnolia Holdings, and 618,921 Common Units held by Magnolia, taking into account the transactions discussed in Item 3.

Note 2: Based on 80,521,228 Common Units outstanding, on an as-converted basis, which equals the sum of (a) 54,451,306 Common Units outstanding as of May 3, 2019, (b) 10,479,528 Common Units issuable upon the conversion of Series A-1 Units outstanding, (c) 4,489,748 Common Units issuable upon the conversion of Series A-2 Units outstanding, (d) 9,808,777 Common Units issuable upon the conversion of Series C Units outstanding and (e) 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person ArcLight Energy Partners Fund V, L.P.
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-l Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 9,795,064 Series C Convertible Preferred Units (“Series C Units”) held by Magnolia Infrastructure Holdings, LLC (“Magnolia Holdings”), convertible into 9,808,777 Common Units, 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016, 10,141,137 Common Units held by Magnolia Holdings, 422,805 Common Units held by JP Energy Development, L.P., 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and approximately 14% owned by AMID GP Holdings, LLC, which is approximately 93% owned by Magnolia Holdings, 618,921 Common Units held by Magnolia and 2,853,482 Common Units held by Busbar II, LLC, taking into account the transactions discussed in Item 3.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person ArcLight PEF GP V, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-l Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 9,795,064 Series C Convertible Preferred Units (“Series C Units”) held by Magnolia Infrastructure Holdings, LLC (“Magnolia Holdings”), convertible into 9,808,777 Common Units, 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016, 10,141,137 Common Units held by Magnolia Holdings, 422,805 Common Units held by JP Energy Development, L.P., 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and approximately 14% owned by AMID GP Holdings, LLC, which is approximately 93% owned by Magnolia Holdings, 618,921 Common Units held by Magnolia and 2,853,482 Common Units held by Busbar II, LLC, taking into account the transactions discussed in Item 3.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person ArcLight Capital Holdings, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-l Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 9,795,064 Series C Convertible Preferred Units (“Series C Units”) held by Magnolia Infrastructure Holdings, LLC (“Magnolia Holdings”), convertible into 9,808,777 Common Units, 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016, 10,141,137 Common Units held by Magnolia Holdings, 422,805 Common Units held by JP Energy Development, L.P., 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and approximately 14% owned by AMID GP Holdings, LLC, which is approximately 93% owned by Magnolia Holdings, 618,921 Common Units held by Magnolia and 2,853,482 Common Units held by Busbar II, LLC, taking into account the transactions discussed in Item 3.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person ArcLight Capital Partners, LLC
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-l Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 9,795,064 Series C Convertible Preferred Units (“Series C Units”) held by Magnolia Infrastructure Holdings, LLC (“Magnolia Holdings”), convertible into 9,808,777 Common Units, 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016, 10,141,137 Common Units held by Magnolia Holdings, 422,805 Common Units held by JP Energy Development, L.P., 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and approximately 14% owned by AMID GP Holdings, LLC, which is approximately 93% owned by Magnolia Holdings, 618,921 Common Units held by Magnolia and 2,853,482 Common Units held by Busbar II, LLC, taking into account the transactions discussed in Item 3.

Schedule 13D

CUSIP No. 02752P 100


1.		Name of Reporting Person Daniel R. Revers
2.		Check the Appropriate Box if a Member of a Group (a) ☐ (b) ☒
3.		SEC Use Only
4.		Source of Funds WC/OO
5.		Check if Disclosure of Legal Proceedings is Required Pursuant to Item 2(d) or 2(e) ☐
6.		Citizenship or Place of Organization Delaware

Note 1: Represents 8,180,101 Series A-l Convertible Preferred Units (“Series A-1 Units”) held by American Midstream GP, LLC (the “General Partner”), which is approximately 86% owned by High Point Infrastructure Partners, LLC (“High Point”), convertible into 10,479,528 common units of the Issuer (“Common Units”), which are indirectly owned by Magnolia Infrastructure Partners, LLC (“Magnolia”), 3,504,604 Series A-2 Convertible Preferred Units (“Series A-2 Units”) held by Magnolia, convertible into 4,489,748 Common Units, 9,795,064 Series C Convertible Preferred Units (“Series C Units”) held by Magnolia Infrastructure Holdings, LLC (“Magnolia Holdings”), convertible into 9,808,777 Common Units, 1,291,869 Common Units issuable upon exercise of the warrant issued to Magnolia Holdings by American Midstream Partners, LP, dated April 25, 2016, 10,141,137 Common Units held by Magnolia Holdings, 422,805 Common Units held by JP Energy Development, L.P., 1,349,609 Common Units held by the General Partner, which is approximately 86% owned by High Point, and approximately 14% owned by AMID GP Holdings, LLC, which is approximately 93% owned by Magnolia Holdings, 618,921 Common Units held by Magnolia and 2,853,482 Common Units held by Busbar II, LLC, taking into account the transactions discussed in Item 3.

This Amendment No. 29 to Schedule 13D amends and supplements the Statement on Schedule 13D filed on May 3, 2013, as amended by Amendment No. 1 filed on November 14, 2014, Amendment No. 2 filed on February 17, 2015, Amendment No. 3 filed on April 3, 2015, Amendment No. 4 filed on May 15, 2015, Amendment No. 5 filed on August 18, 2015, Amendment No. 6 filed on August 19, 2015, Amendment No. 7 filed on September 17, 2015, Amendment No. 8 filed on November 18, 2015, Amendment No. 9 filed on December 22, 2015, Amendment No. 10 filed on January 6, 2016, Amendment No. 11 filed on January 11, 2016, Amendment No. 12 filed on February 1, 2016, Amendment No. 13 filed on February 24, 2016, Amendment No. 14 filed on April 27, 2016, Amendment No. 15 filed on May 18, 2016, Amendment No. 16 filed on November 3, 2016, Amendment No. 17 filed on December 6, 2016, Amendment No. 18 filed on March 8, 2017, Amendment No. 19 filed on August 18, 2017, Amendment No. 20 filed on October 12, 2017, Amendment No. 21 filed on August 20, 2018, Amendment No. 22 filed on September 28, 2018, Amendment No. 23 filed on December 6, 2018, Amendment No. 24 filed on December 11, 2018, Amendment No. 25 filed on January 3, 2019, Amendment No. 26 filed on February 19, 2019, Amendment No. 27 filed on March 19, 2019 and Amendment No. 28 filed on March 29, 2019 (as amended, this “Schedule 13D”), filed with respect to the common units representing limited partner interests (“Common Units”) of American Midstream Partners, LP (the “Issuer”).

Item 3. Source and Amount of Funds or Other Consideration.

Item 3 is hereby amended and supplemented by adding the following immediately after the last paragraph:

On May 7, 2019, the Issuer adopted Amendment No. 10 to the Fifth Amended and Restated Agreement of Limited Partnership of the Issuer, as amended (the “Partnership Agreement”), which revised the Partnership Agreement to permit paid-in-kind quarterly distributions on the Series C Preferred Units made on account of the quarter ending June 30, 2016 and for each quarter thereafter.

On May 7, 2019, in accordance with the terms and conditions of the Partnership Agreement, the Issuer paid quarterly in-kind distributions on (i) the Series A-1 Convertible Preferred Units held by High Point Infrastructure Partners, LLC, in the amount of 239,779 Series A-1 Convertible Preferred Units, (ii) the Series A-2 Convertible Preferred Units held by Magnolia Infrastructure Partners, LLC, in the amount of 102,729 Series A-2 Convertible Preferred Units, and (iii) the Series C Convertible Preferred Units held by Magnolia Infrastructure Holdings, LLC, in the amount of 280,734 Series C PIK Preferred Units.

Item 4. Purpose of Transaction.

The information set forth or incorporated in Item 3 is incorporated herein by reference.

Item 5 Interest in Securities of the Issuer.

Item 5 is hereby amended and supplemented by adding the following immediately after the last paragraph:

(a)-(c) The information contained on the cover pages to this Amendment No. 29 to Schedule 13D and the information set forth and incorporated by reference in Item 3 are incorporated herein by reference.

Item 7. Material to Be Filed as Exhibits.

See the Exhibit Index following the signature pages hereto.

SIGNATURES

After reasonable inquiry and to the best of each of the undersigned’s knowledge and belief, each of the undersigned hereby certifies that the information set forth in this statement is true, complete and correct.

Dated: May 15, 2019


AMERICAN MIDSTREAM GP, LLC

By its Class A Member:

High Point Infrastructure Partners, LLC

/s/ Daniel R. Revers
Daniel R. Revers, President

and

HIGH POINT INFRASTRUCTURE PARTNERS, LLC

/s/ Daniel R. Revers
Daniel R. Revers, President

AMID GP HOLDINGS, LLC

/s/ Daniel R. Revers
Daniel R. Revers, President

HIGH POINT INFRASTRUCTURE PARTNERS, LLC

/s/ Daniel R. Revers
Daniel R. Revers, President

MAGNOLIA INFRASTRUCTURE PARTNERS, LLC

/s/ Daniel R. Revers
Daniel R. Revers, President

JP ENERGY DEVELOPMENT, L.P.

By: JP ENERGY DEVELOPMENT GP LLC, its general partner

/s/ Daniel R. Revers
Name: Daniel R. Revers, President

MAGNOLIA INFRASTRUCTURE HOLDINGS, LLC

/s/ Daniel R. Revers
Daniel R. Revers, President


ARCLIGHT ENERGY PARTNERS FUND V, L.P.

By: ArcLight PEF GP V, LLC, its General Partner
By: ArcLight Capital Holdings, LLC, its Manager
By: ACHP II, L.P., its Managing Member
By: ACH GP, LLC, its General Partner

/s/ Daniel R. Revers
Daniel R. Revers, Manager

ARCLIGHT PEF GP V, LLC

By: ArcLight Capital Holdings, LLC, its Manager
By: ACHP II, L.P., its Managing Member
By: ACH GP, LLC, its General Partner

/s/ Daniel R. Revers
Daniel R. Revers, Manager

ARCLIGHT CAPITAL HOLDINGS, LLC

By: ACHP II, L.P., its Managing Member
By: ACH GP, LLC, its General Partner

/s/ Daniel R. Revers
Daniel R. Revers, Manager

ARCLIGHT CAPITAL PARTNERS, LLC

/s/ Daniel R. Revers
Daniel R. Revers, Managing Partner

/s/ Daniel R. Revers
Daniel R. Revers

EXHIBIT INDEX


Exhibit Number		Description

1.		Amendment No. 10 to the Fifth Amended and Restated Agreement of Limited Partnership of the Issuer (incorporated by reference to Exhibit 3.15 to the Issuer’s Annual Report on Form 10-Q filed May 10, 2019)

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power

0

Shared Voting Power

11,829,136 (See Note 1)

Sole Dispositive Power

0

Shared Dispositive Power

11,829,136 (See Note 1)

American Midstream Partners, LP SC 13D/A