ROCKIES EXPRESS PIPELINE LLC

Incident Narrative

AT APPROXIMATELY 10:45 A.M. CST ON 3/1/16 TALLGRASS FIELD PERSONNEL DISCOVERED A GAS LEAK AT THE SITE OF A HOT TAP ASSEMBLY. ALL PERSONS WERE KEPT AT A SAFE DISTANCE WHILE THE LINE PRESSURE WAS DECREASED TO THE POINT WHERE THE LEAK STOPPED. THE MAINLINE OF THE HOT TAP WAS FULLY BLOWN DOWN IN ORDER FOR THE HOT TAP ASSEMBLY TO BE REPAIRED. THE MAINLINE WAS PLACED BACK IN SERVICE ON THE MORNING OF 3/3/2016. THE GASKET LOCATED IN THE HOT TAP ASSEMBLY BETWEEN THE TOP OF THE SANDWICH VALVE AND THE SPOOL FAILED, CAUSING THE RELEASE OF GAS. THE GASKET MATERIAL HAS A MAXIMUM PRESSURE RATING OF 1400 PSIG WHICH IS BELOW THE PIPELINE MAOP OF 1480 PSIG. THE 1400 PSIG MAX PRESSURE OF THE GASKET WAS EXCEEDED FOR APPROXIMATELY 4 HOURS AND 40 MINUTES ON FEBRUARY 20, 2016, WITH A PEAK OF 1452 PSIG. THIS WAS THE FIRST AND ONLY TIME THE PRESSURE EXCEEDED 1400 PSIG. THE GASKET SUPPLIED BY THE HOT TAP CONTRACTOR WAS NOT ADEQUATE FOR THE ESTABLISHED MAOP OF THE PIPELINE, AND THE SPECIFICATIONS OF THE MATERIALS USED WERE NOT VERIFIED BY ANYONE ON SITE. DURING THE INCIDENT INVESTIGATION IT WAS NOTED THAT WHEN REMOVING THE BOLTS THE HOT TAP CONTRACTOR SAID THEY APPEARED TO BE OVER-TORQUED, WHICH MAY HAVE LED TO INADEQUATE SEALING OVER TIME BETWEEN THE FLANGES AND THE GASKET IN QUESTION.