SOUTHWEST GAS CORP

Incident Narrative

WHILE CONDUCTING A SPECIAL LEAK PATROL ON M7000/8000 PIPE, A COMPANY CONTRACTOR FROM HEATH CONSULTANTS DISCOVERED A HAZARDOUS GRADE 1 LEAK ON A 2-INCH M8000 PIPE AT THE 2""X1"" CONTINENTAL TAPPING SADDLE NEAR THE INTERSECTION OF BUCKSKIN AVENUE AND SHADY TIMBER STREET IN LAS VEGAS, NEVADA. THE FLOW OF GAS TO THE SECTION OF PIPE WAS TAKEN OUT OF SERVICE WHILE REPAIRS WERE COMPLETED WHICH RESULTED IN A SERVICE OUTAGE OF 1,722 CUSTOMERS. G2 - NATURAL FORCE DAMAGE: THE COMPANY COMPLETED IT'S INVESTIGATION INTO THE FAILURE AND DETERMINED THE APPARENT CAUSE OF THE LEAK TO BE ""NATURAL FORCE DAMAGE"", WITH A SUB-CAUSE OF ""TEMPERATURE - THERMAL STRESS"". THE TAPPED HOLE IN THE PIPE WAS AXIALLY DISPLACED APPROXIMATELY ONE INCH WITH RESPECT TO THE TAPPING TEE'S ORIGINAL POSITION. THE MOVEMENT OF THE PIPE, LIKELY DUE TO THERMAL CONTRACTION, RESULTED IN THE DISPLACEMENT OF THE SADDLE-TO-PIPE O-RING, BREAKING THE GAS-TIGHT SEAL RESULTING IN A LEAK. BASED ON COMMUNICATIONS THAT THE PUBLIC UTILITES COMMISSION OF NEVADA'S REGULATORY OPERATIONS STAFF HAD WITH THE PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION'S ACCIDENT INVESTIGATION DIVISION, PART A, 4 ""LOCAL TIME AND DATE OF THE INCIDENT"" REFLECTS THE TIME OPERATOR PERSONNEL IDENTIFIED AND REPORTED A GRADE 1 LEAK ON THE PIPELINE. AT THE TIME, NO INCIDENT REPORTING CRITERIA WAS MET. THE SHUTDOWN TIME REPORTED IN PART A, 13A (11:23 PDT) IS THE EARLIEST DATE AND TIME A REPORTING CRITERIA WAS MET. DUE TO THE SHUTDOWN OF THE PIPELINE, THE INCIDENT WAS ESTIMATED TO REACH PROPERTY DAMAGE OF $50,000 OR MORE. TELEPHONIC NOTIFICATIONS WERE MADE WITHIN ONE HOUR OF THE SHUTDOWN TIME. PART A, 6: SOUTHWEST GAS NOTIFIED THE NATIONAL RESPONSE CENTER (NRC) TELEPHONICALLY OF THE INCIDENT ON SEPTEMBER 20, 2018 AT 11:43 PDT. THE NRC ISSUED REPORT NUMBER 1225212 FOR THE INCIDENT. SOUTHWEST GAS PROVIDED A 48-HOUR UPDATE TELEPHONICALLY TO THE NRC ON SEPTEMBER 21, 2018 AT 15:48 PDT. THE NRC ISSUED REPORT NUMBER 1225343 FOR THE UPDATED REPORT.