ATMOS ENERGY CORPORATION - MID-TEX

Incident Narrative

ON FRIDAY, NOVEMBER 6, 2020, AT APPROXIMATELY 2:30 P.M., A THIRD-PARTY CONTRACTOR CUT THE NATURAL GAS SERVICE LINE TO HIGHLAND PARK HIGH SCHOOL WHEN PERFORMING A SAW CUT IN WESTCHESTER DRIVE. ATMOS ENERGY CREWS RESPONDED BY MAKING THE AREA SAFE, EVACUATING THE HIGH SCHOOL, AND THEN BEGAN THE PROCESS OF RESTORING SERVICE TO THE HIGH SCHOOL. THE MAIN LINE IN THE AREA CONSISTED OF 4"" STEEL PIPE. HOWEVER, THE REPAIR REQUIRED THE INSTALLATION OF A POLY TRANSITION FITTING FROM THE STEEL MAIN TO THE 3"" STEEL SERVICE LINE AS WELL AS THE INSTALLATION OF A POLY VALVE. A BELL HOLE WAS DUG AT THE LOCATION OF THE DAMAGE AND WHERE THE MAIN TO SERVICE LINE CONNECTION WAS BEING REPLACED. ON THE MORNING OF SATURDAY, NOVEMBER 7, REPAIRS HAD BEEN COMPLETED ON THE SEGMENT OF MAIN UP TO THE CLOSED POLY VALVE AND WAS ACTIVE WITH NATURAL GAS. ATMOS ENERGY EMPLOYEES WERE PREPARING TO PERFORM ADDITIONAL WORK THAT WAS REQUIRED FOR THE SERVICE LINE WHEN NATURAL GAS SUDDENLY ESCAPED AND IGNITED AT APPROXIMATELY 9:20 A.M. TWO EMPLOYEES WERE INJURED AND WERE TAKEN TO THE HOSPITAL. ONE EMPLOYEE WAS TREATED AND RELEASED, AND THE OTHER WAS ADMITTED TO THE HOSPITAL AT 11:17 AM. THE PROBABLE CAUSE OF THIS INCIDENT WAS THE FAILURE AND RELEASE OF THE 4"" ELECTROFUSION COUPLING THAT OCCURRED WITHIN THE NORTH BELL HOLE. THE JOINT FAILURE WAS SUDDEN AND OCCURRED AFTER THE COUPLING WAS INSTALLED AND PLACED IN SERVICE. THE JOINT FAILURE AND SEPARATION OF THE COUPLING OCCURRED WITHIN THE SAME EXCAVATED BELL HOLE THAT THE RESULTING INJURED CREW MEMBERS WERE WORKING DOWNSTREAM PERFORMING FINAL SYSTEM TIE-INS. THE MOST LIKELY SOURCE OF IGNITION OCCURRED FROM THE ENERGIZED FITTING BEING FUSED (4"" EF COUPLING) ON THE OUTLET SIDE OF THE VALVE. NONE OF THESE ACTIVITIES PROVIDED EVIDENCE OF A DIRECT CAUSE OF FAILURE. SINCE THE MATERIALS INVOLVED IN THE FAILURE WERE DESTROYED IN THE RESULTING FIRE, LABORATORY TESTING CANNOT BE CONDUCTED ON THE FAILED FITTING TO FURTHER EVALUATE ROOT CAUSE. HOWEVER, TESTING WAS CONDUCTED ON OTHER ELEMENTS IN INVESTIGATION OF THE ROOT CAUSE SUCH AS THE ELECTROFUSION PROCESSOR UNIT, THE DOWNSTREAM VALVE, AND PRIOR FUSIONS PERFORMED BY THE SAME QUALIFIED EMPLOYEE.