| Popb NM Crude II LLC | Owner/operator | Houston, TX | | 1 |
| Port Arthur LNG North, LLC | Owner/operator | | 1 | |
| Port Arthur Lng, LLC | Owner/operator | | 1 | |
| Port Arthur Lng, Llc, Port Arthur Pipeline, LLC | Owner/operator | | 1 | |
| Port Arthur Pipeline LLC | Owner/operator | | 7 | |
| Port Arthur Terminal LLC | Owner/operator | Houston, TX | | 2 |
| Port Barre Investments LLC | Owner/operator | | 2 | |
| Port Barre Investments, L.L.C. d/b/a Bobcat Gas Storage | Owner/operator | | | |
| Port Dolphin Energy LLC | Owner/operator | | 1 | |
| Port Westward Power Plant | Owner/operator | Portland, OR | | 1 |
| Portland General Electric Company | Owner/operator | | | |
| Portland Natural Gas Transmission System | Owner/operator | Houston, TX | 11 | 1 |
| Portland Pipeline Corp | Owner/operator | South Portland, ME | | 1 |
| Poseidon Oil Pipeline | Owner/operator | | 1 | |
| Post Oak Midstream | Owner/operator | Houston, TX | | 7 |
| Postrock KPC Pipeline, LLC | Owner/operator | | | |
| Potac, LLC | Owner/operator | Corpus Christi, TX | | 36 |
| Potato Hills Gas Gathering | Owner/operator | Tulsa, OK | | 1 |
| Powder River Holdings, LLC | Owner/operator | | | 1 |
| Powder River Operating, LLC | Owner/operator | Houston, TX | | 1 |
| Power Line Holdings, Inc. | Contractor | | | |
| Power Line Services, Inc. | Contractor | | | |
| PowerTeam Services, LLC | | | | |
| Ppg, LLC | Owner/operator | E. Lansing, MI | | 1 |
| Prairie Pipeline Co | Owner/operator | Dallas, TX | | 2 |
| Prairieland Pipeline, LLC | Owner/operator | Palestine, IL | | 1 |
| Prairielands Energy Marketing, Inc | Owner/operator | | | |
| Praxair, Inc | Owner/operator | | 3 | |
| Pre-Ongard Well Operator | Owner/operator | | | 1 |
| Precision Drilling Company, LP | Contractor | | 1 | |
| Precision Infrastructure, LLC | Contractor | | | |
| Precision Pipeline, LLC | Contractor | Eau Claire, WI | 38 | |
| Precision West, LLC | Contractor | | | |
| Premcor Pipeline Co., The | Owner/operator | | | 7 |
| Premcor Refining Group Inc | Owner/operator | | | 3 |
| Premier Natural Resources Ii, LLC | Owner/operator | Tulsa, OK | | 1 |
| Premier Plant Services LLC | Owner/operator | | | 1 |
| Presidio Petroleum LLC | Owner/operator | Fort Worth, TX | | 2 |
| Price Gregory International, LLC | Contractor | Katy, TX | 60 | |
| Price Gregory Services, Incorporated | Contractor | Houston, TX | 1 | |
| Pride Refining, Inc. | Owner/operator | | | 2 |
| Prime Inspections | NDT | | | |
| Primoris Pipeline | Contractor | | 1 | |
| Primoris Services Corporation | Contractor | Dallas, TX | 2 | |
| Primrose Resources, LLC | Owner/operator | | | 1 |
| Prince George's County Government | Owner/operator | | | |
| Prince Georges County Government | Owner/operator | Largo, MD | | |
| Princess Three Corporation | Owner/operator | | | |
| Princess Three Operating, LLC | Owner/operator | | | 1 |
| Prism Gas Systems I, L.p. | Owner/operator | Bedford, TX | | 2 |