Interstate natural gas transmission pipelines

One of the largest energy infrastructure companies in North America; holds natural gas and NGL storage assets including salt cavern storage. Kinder Morgan's Products Pipelines segment operates refined products and NGL pipelines with associated storage. Also a leading operator of liquefied natural gas (LNG) facilities and CO2 pipelines for enhanced oil recovery. Less dominant in LPG salt cavern storage specifically vs. Enterprise/Energy Transfer/ONEOK, but holds meaningful storage capacity.

Williams Companies, Inc. (Tulsa, Oklahoma; NYSE: WMB) is the operator of the Transco pipeline — the largest US natural gas pipeline by volume, running approximately 1,800 miles from the Gulf Coast through Virginia and the Carolinas to New York City. Williams handles approximately 30% of all US natural gas consumed daily across its network. The Transco system alone carries roughly 15% of total US natural gas consumption and supplies approximately 30% of East Coast natural gas demand. Williams also operates Gulfstream Natural Gas System (Florida) and Northwest Pipeline (Pacific Northwest). Total operated pipeline: ~33,000 miles. 2023 revenues approximately $10.2 billion.

TC Energy Corporation (Calgary, Alberta; TSX/NYSE: TRP) is one of the largest operators of underground natural gas storage in the northeastern US through its Columbia Gas Transmission subsidiary. Columbia Gas Transmission operates approximately 30 underground storage fields in West Virginia, Ohio, Pennsylvania, Virginia, and Kentucky — the largest concentration of UGS fields by count in the US. These fields have combined working gas capacity of approximately 600 Bcf, serving the Northeast and Mid-Atlantic markets. TC Energy's storage is primarily in depleted gas reservoir fields in the Appalachian Basin. The Columbia storage system plays a critical role in winter peak supply for the most densely populated region of the US. In addition, TC Energy's Canadian Mainline pipeline system includes storage fields in Ontario (Dawn Hub — the most liquid natural gas trading hub in Canada).

Major US midstream partnership; holds NGL and LPG salt cavern storage at Mont Belvieu (Lone Star NGL/Energy Transfer). Also operates Mariner East pipeline system connecting Appalachian NGLs to Marcus Hook PA export terminal. Marcus Hook exports ~20% of US propane, requiring coordinated storage drawdown from Mont Belvieu caverns. Diverse midstream footprint: natural gas, crude oil (Dakota Access), NGLs, and refined products.

Boardwalk Pipeline Partners LP (Houston, Texas; private subsidiary of Loews Corporation) operates Gulf South Pipeline Company (approximately 7,200 miles across Louisiana, Mississippi, Alabama, Georgia, Florida, Tennessee, Arkansas, and Texas — serving Gulf Coast industrial customers, power generators, and LDCs) and Texas Gas Transmission (approximately 6,400 miles connecting Gulf Coast to Midwest — Illinois, Indiana, Ohio, Kentucky, Tennessee). Combined system: approximately 14,000 miles serving 9 Bcf/day capacity. Boardwalk is notable as the only major US interstate gas pipeline operator that is a fully private subsidiary of a public holding company (Loews Corporation) rather than a publicly traded MLP. Loews took Boardwalk private in 2018 for approximately $1.5 billion.