SOUTHERN STAR CENTRAL GAS PIPELINE, INC

Incident Narrative

AT 2:42 PM LOCAL TIME ON 8/6/2018 SOUTHERN STAR CENTRAL GAS PIPELINE (SSCGP) RECEIVED A CALL FROM HARPER COUNTY, OKLAHOMA, EMERGENCY RESPONDERS ABOUT THE SOUND OF A GAS LEAK. SSCGP SCADA CONTROLLER IMMEDIATELY NOTICED THE PRESSURE DROPPING ON LINE N. SSCGP CALLED A SIGNIFICANT EVENT AND DISPATCHED THE FIELD CREWS TO THE LOCATION. SSCGP CALLED THE NRC AT 3:26 PM. A SEPARATE CALL WAS MADE TO PHMSA AT 3:43 PM AND A FOLLOW UP CALL WAS MADE AT 4:07 PM. THE FIELD CREW ARRIVED AT THE BUFFALO ML GATE WEST OF THE RUPTURE SITE AND HAD IT CLOSED BY 3:32 PM. THEY PROCEEDED TO THE DOBY ML GATE APPROXIMATELY 11 MILES TO THE EAST OF THE BUFFALO MLG AND HAD IT CLOSED BY 3:51 PM. THE FIELD CREW THEN PROCEEDED TO THE RUPTURE SITE, ARRIVED AT 3:58 PM AND CONFIRMED THAT THE RUPTURE WAS EFFECTIVELY ISOLATED. LOCAL EMERGENCY RESPONDERS ARRIVED ON SITE AT APPROXIMATELY 3:30 PM AND HAD THE AREA SECURED BY 3:58 PM. PHMSA INVESTIGATORS EXAMINED THE SITE BEFORE ANYTHING WAS DISTURBED. AFTER BEING GIVEN PERMISSION, THE DAMAGED SECTION OF PIPE WAS SHIPPED TO G2MT LABORATORIES IN HOUSTON, TEXAS FOR METALLURGICAL EXAMINATION. SSCGP THEN MADE ARRANGEMENTS TO REPAIR THE DAMAGE AND PLACED THE AFFECTED SECTION OF LINE N BACK IN SERVICE ON 8/10/2018 AT 10:50 AM LOCAL TIME UNDER A VOLUNTARY 20% PRESSURE REDUCTION. 112 FEET OF 26"" 0.375"" WALL X70 PIPE WAS INSTALLED TO MAKE THE PERMANENT REPAIR. THE AFFECTED SECTION OF LINE N WILL CONTINUE TO BE OPERATED AT A 20% PRESSURE REDUCTION PENDING THE RESULTS OF FURTHER INVESTIGATION. THE INITIAL INCIDENT REPORT INDICATED HYDROGEN STRESS CRACKING AS THE CAUSE BASED ON INITIAL ANALYSIS BY G2MT. KEIFNER AND ASSOCIATES PERFORMED AN ADDITIONAL METALLURGICAL EXAMINATION AND SUBMITTED THE DRAFT RESULTS TO SSCGP ON 2/26/2019. THE KEIFNER METALLURGICAL REPORT FINDS THE CAUSE OF THE RUPTURE WAS HIGH PH STRESS CORROSION CRACKING. PART G HAS BEEN REVISED TO REFLECT THE FINDINGS OF THE KEIFNER METALLURGICAL EXAMINATION.