TEXAS EASTERN TRANSMISSION, LP

Incident Narrative

ON MAY 4, 2023 AT 2:30 P.M. CST, A THIRD PARTY DISCOVERED BUBBLES IN THE GULF OF MEXICO AND CONTACTED WITT O'BRIEN'S RESPONSE, WITT O'BRIEN SUBSEQUENTLY MADE THE NOTIFICATION TO THE NRC AT 3:58 PM CST. PHMSA NOTIFIED ENBRIDGE GAS CONTROL (TETLP) OF THE EVENT AND PROVIDED THE COORDINATES OF THE LEAK. TETLP BEGAN INVESTIGATING THE LEAK AND NOTIFYING PRODUCERS TO SHUT IN PRODUCTION ON THE SYSTEM AT APPROXIMATELY 6:00 PM ON MAY 4, 2023. TETLP MADE THE INITIAL NOTIFICATION TO THE NRC ON MAY 5, 2023 AT 6:50 PM CST UPON CONFIRMED DISCOVERY (BASED ON THE COORDINATES, ASSUMPTION THAT THE LEAK WAS ON TETLP'S LINE 40-B-4 AND ESTIMATED REPAIR COSTS WHICH EXCEEDED THE PHMSA REPORTING THRESHOLD OF AN INCIDENT). TETLP WAS UNABLE TO SECURE A DIVING VESSEL CONTRACTOR UNTIL MAY 8, 2023 DUE TO CONTRACTOR AVAILABILITY IN THE GULF COAST REGION. AT APPROXIMATELY 8:00 AM CST ON MAY 9, 2023 TETLP CONFIRMED THAT THE LEAK WAS ON TETLP'S 24 INCH, LINE 40-B-4. TETLP IMMEDIATELY MOBILIZED A LIFT BOAT TO START ISOLATION AND BLOWDOWN. LINE 40-B-4 WAS ISOLATED AND DEPRESSURIZED ON MAY 11, 2023. THE LEAK WAS REPAIRED BY INSTALLING A MECHANICAL COUPLING ON MAY 20, 2023. A LEAK TEST WAS SUCCESSFULLY PERFORMED ON THE MECHANICAL COUPLING AND THE LINE RE-PRESSURIZED AND RETURNED BACK TO SERVICE ON MAY 20, 2023. THE LEAK WAS 1/2 IN. DIAMETER IN A FIELD JOINT LOCATED AT THE 6 O'CLOCK POSITION, THAT WAS CAUSED BY INTERNAL CORROSION. THE ROOT CAUSE IS BELIEVED TO BE DUE TO THE INTERNAL CORROSION AT THE WELD ON THE LOW POINT OF THE LINE.