Boardwalk Pipeline Partners, LP

Item 1.01 Entry into a Material Definitive Agreement. On November 13, 2025, Boardwalk Pipeline Partners, LP (the “Company”), a Delaware limited partnership, and Boardwalk Pipelines, LP (“Boardwalk Pipelines”), a Delaware limited partnership and a wholly-owned subsidiary of the Company, entered into an Underwriting Agreement (the “Underwriting Agreement”) with Barclays Capital Inc., Citigroup Global Markets Inc., MUFG Securities Americas Inc. and Wells Fargo Securities, LLC, as representatives of the several underwriters set forth in Schedule 1 to the Underwriting Agreement (the “Underwriters”), with respect to the issue and sale by Boardwalk Pipelines of $550.0 million in aggregate principal amount of its 5.375% Senior Notes due 2036 (the “Notes”), in an underwritten public offering (the “Debt Offering”). The Notes will be fully and unconditionally guaranteed on a senior unsecured basis by the Company (the “Guarantee” and, together with the Notes, the “Securities”). The Securities to be sold in the Debt Offering were registered under the Securities Act of 1933, as amended, pursuant to a shelf registration statement on Form S-3 (File No. 333-274067). A copy of the Underwriting Agreement is filed as Exhibit 1.1 to this report and is incorporated by reference herein. The Notes will be issued pursuant to an indenture, dated as of August 21, 2009, between Boardwalk Pipelines, as issuer, the Company, as guarantor, and The Bank of New York Mellon Trust Company, N.A. as trustee (the “Trustee”), as amended by the Third Supplemental Indenture thereto, dated as of April 18, 2013, and to be supplemented by the Eleventh Supplemental Indenture thereto to be dated on or about November 24, 2025, between Boardwalk Pipelines, the Company and the Trustee. Closing of the Debt Offering is expected to occur on November 24, 2025. Boardwalk Pipelines intends to use the net proceeds of approximately $543.8 million from this offering (after deducting the underwriting discount and estimated offering expenses) to retire the outstanding $550.0 million aggregate principal amount of the 5.95% notes due 2026 of Boardwalk Pipelines at or prior to maturity. The description set forth above in Item 1.01 is qualified in its entirety by the Underwriting Agreement. A copy of the Underwriting Agreement is filed as an exhibit to this report and is incorporated by reference herein.