SOUTHWEST GAS CORP

Incident Narrative

PL 2021-0128 SOUTHWEST GAS CORPORATION (SWG) RESPONDED TO A REPORTED FIRE AT 4940 WEST RAY ROAD IN CHANDLER CALLED IN BY THE FIRE DEPARTMENT AT 09:30. SWG CONSTRUCTION TECHNICIAN RESPONDED TO FIND A STRIP-MALL THAT APPEARED TO BE DAMAGED BY AN EXPLOSION. FIRE DEPARTMENT REPORTED THAT FOUR PEOPLE WERE TRANSPORTED TO THE HOSPITAL WITH INJURIES. SWG CREWS RESPONDED AND CONTROLLED THE FLOW OF GAS BY SQUEEZING THE 2-INCH PLASTIC PIPELINE THAT SUPPLIES GAS TO THE COMMERCIAL PROPERTY RESULTING IN AN OUTAGE OF SEVEN ACTIVE ACCOUNTS (SIX COMMERCIAL AND ONE RESIDENTIAL). NOTIFICATION WAS MADE TO PHMSA VIA THE NATIONAL RESPONSE CENTER (NRC) ON AUGUST 26, 2021 AT 11:09 AND WAS GIVEN NRC REPORT #1314811. AN UPDATE WAS PROVIDED TO THE NRC ON AUGUST 27, 2021 AT 11:31 AND WAS GIVEN NRC REPORT #1314910. NOTIFICATION WAS MADE TO CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD (CSB) ON AUGUST 26,2021 AT 12:05. THE APPARENT LEAK CAUSE IS LISTED AS G5 - PIPE, WELD, OR JOINT FAILURE. THE INCIDENT INVESTIGATION IS STILL ONGOING, AND A SUPPLEMENTAL REPORT WILL BE SUBMITTED UPON COMPLETION OF THE INVESTIGATION BY SWG. NOTE: FOR PART A, #10, THE ESTIMATED VOLUME OF GAS RELEASED THAT IS IDENTIFIED REPRESENTS AN ESTIMATE THAT PRESUMES A CRACK THAT IS LEAKING AT 56 PSI, BEGINNING AT THE TIME OF THE INITIAL REPORT OF THE INCIDENT AND ENDING AT THE TIME THE PIPELINE WAS SHUT DOWN. HOWEVER, THE ACTUAL AMOUNT OF GAS LOSS IS UNKNOWN BECAUSE THE TIME THE GAS PIPELINE BEGAN LEAKING IS UNKNOWN. SUPPLEMENTAL REPORT: LABORATORY DATA ANALYSIS SHOWS THE LEAK WAS CAUSED BY THERMAL-OXIDATIVE DEGRADATION EXTENDING FROM THE INNER WALL TO THE MID-WALL OF THE TUBING THAT RESULTED IN A THROUGH-WALL AXIAL CRACK. SECTION G5 WAS UPDATED FROM ""SLIT CRACK"" TO ""THERMAL-OXIDATIVE DEGRADATION"".