Exhibit 3.1

Execution Copy

AMENDMENT NO. 2 TO

SECOND AMENDED AND RESTATED AGREEMENT OF LIMITED

PARTNERSHIP

OF

ENERGY TRANSFER PARTNERS, L.P.

This Amendment No. 2 (this “Amendment No. 2”) to the Second Amended and Restated Agreement of Limited Partnership of Energy Transfer Partners, L.P. (the “Partnership”), dated as of July 28, 2009, as amended by Amendment No. 1 thereto dated as of March 26, 2012 (as so amended, the “Partnership Agreement”) is hereby adopted effective as of October 5, 2012, by Energy Transfer Partners GP, L.P., a Delaware limited partnership (the “General Partner”), as general partner of the Partnership. Capitalized terms used but not defined herein have the meaning given such terms in the Partnership Agreement.

WHEREAS, Section 13.1(d)(i) of the Partnership Agreement provides that the General Partner, without the approval of any Partner, may amend any provision of the Partnership Agreement to reflect a change that, in the discretion of the General Partner, does not adversely affect the Unitholders in any material respect; and

WHEREAS, Section 13.1(g) of the Partnership Agreement provides that the General Partner, without the approval of any Partner (subject to Section 5.7 of the Partnership Agreement), may amend any provision of the Partnership Agreement, to reflect an amendment that, in the discretion of the General Partner, is necessary or advisable in connection with the authorization of issuance of any class or series of Partnership Securities pursuant to Section 5.6 of the Partnership Agreement; and

WHEREAS, the General Partner has entered into an Agreement and Plan of Merger (as amended, the “Merger Agreement”) by and among the Partnership, the General Partner, Sam Acquisition Corporation, a Pennsylvania corporation (“Merger Sub”), and Sunoco, Inc. a Pennsylvania corporation (the “Company”), pursuant to which Merger Sub will be merged with and into the Company (the “Merger”), with the Company surviving the Merger; and

WHEREAS, in connection with the transactions contemplated by the Merger Agreement, the Partnership is obligated to issue limited partner interests to be designated as Class F Units having the rights, preferences and privileges set forth in this Amendment No. 2; and

WHEREAS, the General Partner has determined that the creation of the new class of Partnership Securities to be designated as “Class F Units” provided for in this Amendment No. 2 will be in the best interests of the Partnership and beneficial to the Limited Partners, including the holders of the Common Units; and

WHEREAS, the General Partner has determined, pursuant to Section 13.1(g) of the Partnership Agreement, that the amendments to the Partnership Agreement set forth herein (other than those amendments to Section 6.4 of the Partnership Agreement) are necessary or advisable in connection with the authorization of the issuance of the Class F Units; and

WHEREAS, acting pursuant to the power and authority granted to it under Section 13.1(d)(i) of the Partnership Agreement, the General Partner has determined that the following amendment to Section 6.4 of the Partnership Agreement does not adversely affect the Unitholders in any material respect; and

NOW THEREFORE, the General Partner does hereby amend the Partnership Agreement as follows:

Section 1. Amendment.

(a) Section 1.1 of the Partnership Agreement is hereby amended to add or amend and restate the following definitions in the appropriate alphabetical order:

(i) “Class F Percentage” means, with respect to the Class F Units for any date, the percentage determined by multiplying (a) 35% by (b) the quotient obtained by dividing (A) the number of Class F Units Outstanding on such date, by (B) 90,706,000.

(ii) “Class F Issue Price” means $50.00.

(iii) “Class F Unit” means a Unit representing a fractional part of the Partnership Interests of all Limited Partners and Assignees and of the General Partner (exclusive of its interest as holder of the general partner interest and the Incentive Distribution Rights) and having the rights and obligations specified with respect to Class F Units in this Agreement.

(iv) “Company” means Sunoco, Inc., a Pennsylvania corporation.

(v) “Company Merger” means the merger of Merger Sub with and into the Company, contemplated by the Company Merger Agreement.

(vi) “Company Merger Agreement” means the Agreement and Plan of Merger by and among the Partnership, the General Partner, Merger Sub, and the Company, pursuant to which Merger Sub will be merged with and into the Company.

(vii) “ETP Holdco” means ETP Holdco Corporation, a Delaware corporation.

(viii) “ETP Holdco Distributions” has the meaning set forth in Section 5.10(b)(iii)(A).

(ix) “ETP Holdco Items” has the meaning set forth in Section 5.10(b)(ii)(A).

(x) “Merger Sub” has the meaning ascribed to such term in the Company Merger Agreement.

(xi) “Quarterly Reduction Amount” has the meaning set forth in Section 6.4(c).

(xii) “Unit” means a Partnership Interest of a Limited Partner or Assignee in the Partnership and shall include Common Units, Class E Units and Class F Units, but shall not include (x) the general partner interest in the Partnership or (y) Incentive Distribution Rights.

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(xiii) “Unitholders” means the holders of Common Units, Class E Units and Class F Units.

(xiv) “Unit Majority” means at least a majority of the Outstanding Units (excluding the Class E Units and Class F Units in respect of matters in which the holders of the Class E Units and Class F Units are not entitled to a vote).

(b) Article V of the Partnership Agreement is hereby amended by adding a new Section 5.10 at the end thereof as follows:

“5.10 Establishment of Class F Units.

(a) General. The General Partner hereby designates and creates a series of Units to be designated as “Class F Units” and consisting of a total of 90,706,000 Class F Units.

(b) Rights of Class F Units. The Class F Units shall have the following rights, preferences and privileges and shall be subject to the following duties and obligations:

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(c) Section 6.1(a)(iii)(A)(II) of the Partnership Agreement is hereby amended by replacing “HHI Distributions” with “ETP Holdco Distributions” where such term is used.

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(d) Section 6.1(d)(xiii) of the Partnership Agreement is hereby amended by (i) changing the subtitle to “Class E and ETP Holdco Allocations,” (ii) replacing “HHI” with “ETP Holdco” each place where such term is used, (iii) deleting the parenthetical containing “HHI Items” in clause (A), and (iv) replacing “HHI Items” with “ETP Holdco Items” each other place where the term “HHI Items” is used.

(e) Section 6.3(e)(i) of the Partnership Agreement is hereby amended and restated as follows:

“(i) For each taxable year, no portion of any Partnership cash distributions that are ETP Holdco Distributions shall be distributed to the Class E Units.”

(f) Section 6.3(e)(ii) of the Partnership Agreement is hereby amended by replacing “HHI Distributions” with “ETP Holdco Distributions” where such term is used.

(g) Section 6.4 of the Partnership Agreement is hereby amended by adding a new subsection (c) as follows:

“(c) Notwithstanding anything to the contrary in this Section 6.4, and without limiting the provisions of Subsection 6.4(b), for a period of twelve consecutive Quarters commencing with the Quarter in which the Company Merger is consummated, aggregate quarterly distributions, if any, to the holders of the Incentive Distribution Rights provided for in clauses (iii)(B), (iv)(B) and (v)(B) of Subsection 6.4(a) shall be reduced by $17,500,000 per Quarter (the “Quarterly Reduction Amount”); provided, that if any such reduction for a Quarter would result in a negative number, then the Quarterly Reduction Amount for such Quarter shall be adjusted and deemed to be an amount that would result in zero quarterly distributions for such Quarter to the holders of Incentive Distribution Rights provided for in clauses (iii)(B), (iv)(B) and (v)(B) of Subsection 6.4(a).”

Section 2. Except as hereby amended, the Partnership Agreement shall remain in full force and effect.

Section 3. This Amendment shall be governed by, and interpreted in accordance with, the laws of the State of Delaware, all rights and remedies being governed by such laws without regard to principles of conflicts of laws.

[Signature page follows]

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IN WITNESS WHEREOF, this Amendment has been executed as of the date first above written.

[Signature Page to Amendment No. 2 to ETP Partnership Agreement]