SOUTHERN NATURAL GAS CO

Incident Narrative

ON FEBRUARY 13, 2022, SOUTHERN NATURAL GAS COMPANY, LLC (SNG) 18-INCH SOUTH MAIN LINE EXPERIENCED AN IN-SERVICE FAILURE RESULTING IN A PIPELINE RUPTURE WITH FIRE. THE PRELIMINARY TIMELINE OF EVENTS IS AS FOLLOWS: 16:15-HOURS, AN UNDESIRED RELEASE OF NATURAL GAS OCCURRED ON THE SNG 18-INCH SOUTH MAIN LINE. 16:20-HOURS, PERRY COUNTY SHERRIFF ARRIVED ON SCENE, BLOCKED A LOCAL ROAD AND INSTRUCTED ARRIVING DEPUTIES TO SECURE THE AREA. 16:31-HOURS, A CITIZEN CALLED SNG GAS CONTROL AND REPORTED A FIRE NEAR THE 18-INCH SOUTH MAIN LINE ROW. 16:33-HOURS, SNG GAS CONTROL RECEIVED A CALL FROM ANOTHER CITIZEN REGARDING THE FIRE. 16:34-HOURS, SNG GAS CONTROL NOTIFIED SNG OPERATIONS OF A PRESSURE DROP AT THE GALLION COMPRESSOR STATION AND SELMA COMPRESSOR STATION AND A POTENTIAL RUPTURE NEAR THE 18-INCH SOUTH MAIN LINE SYSTEM. 16:52-HOURS, SNG OPERATIONS LOCATED THE PIPELINE RUPTURE ON THE SOUTH MAIN LINE SYSTEM AT MP 155.755. 17:15-HOURS, SNG EMERGENCY RESPONSE LINE+ (ERL+) CALL NOTIFICATIONS INITIATED PER SNG PROCEDURES TO COORDINATE THE EMERGENCY RESPONSE. 17:26-HOURS, SNG OPERATOR #1 CLOSED UPSTREAM GATE VALVE #18 LOCATED AT, MP 150.783. 17:33-HOURS, SNG INITIATED CALL TO NRC. (REPORT NUMBER 1328835) 17:39-HOURS, SNG OPERATOR #2 CLOSED CROSSOVER VALVE 155 LOCATED AT, MP 155.000. 17:41-HOURS, SNG OPERATOR #3 CLOSED DOWNSTREAM GATE VALVE #19 LOCATED AT, MP 159.054, COMPLETELY ISOLATING THE SOUTH MAIN LINE SYSTEM. 22:01-HOURS, THE FIRE WAS EXTINGUISHED. SNG'S INVESTIGATION BEGAN ON FEBRUARY 14, 2022 AND RECEIVED A CORRECTION ACTION ORDER (CAO) CPF NO. 2-2022-007-CAO FROM PHMSA ON FEBRUARY 18, 2022. SNG SENT THE FAILED SPECIMEN TO A THIRD-PARTY METALLURGICAL LABORATORY. THE METALLURGICAL REPORT WAS COMPLETED ON APRIL 4, 2022 AND CONCLUDED THAT THE SNG 18-INCH SOUTH MAIN LINE RUPTURED LIKELY FROM A HYDROGEN STRESS CRACK INITIATED AT THE PIPE OD IN A LOCALIZED HARD SPOT. IN ORDER TO PREVENT REOCCURRENCE SNG AND ITS ILI VENDOR PERFORMED A FOOT-BY-FOOT MANUAL ANALYSIS OF ALL AVAILABLE RESIDUAL DATA SETS ON THE 18-INCH LINE TO IDENTIFY SIMILAR CONDITIONS TO THOSE IN THE FAILED JOINT. SNG REMEDIATED 21 FEATURES WITH SIMILAR CHARACTERISTICS TO THE ANOMALY IN THE FAILED JOINT. IN ADDITION TO THE REMEDIATION PROJECT SNG WILL IMPLEMENT TESTING, AND INTEGRITY VERIFICATION MEASURES, TO PROMOTE THE ONGOING SAFE OPERATION OF THE PIPELINE CONSIDERING THE RESULTS OF THE ANALYSES, INSPECTIONS, EVALUATIONS, AND CORRECTIVE MEASURES UNDERTAKEN PURSUANT TO THE CAO. THE PIPELINE WAS RETURNED TO SERVICE ON AUGUST 31, 2022, FOLLOWING THE REQUIREMENTS FROM THE CAO. SNG SUBMITTED THE FINAL QUARTERLY REPORT ON SEPTEMBER 29, 2022 AND REQUESTED CAO CLOSURE.