TALLGRASS INTERSTATE GAS TRANSMISSION, LLC

Incident Narrative

AT APPROXIMATELY 19:55 LOCAL TIME ON JUNE 13, 2013, A PIPE SECTION OF THE TIGT 12"" LINGLE TO MITCHELL MAINLINE IN UNINCORPORATED (CLASS 1 AREA) GOSHERN COUNTY, WY RUPTURED DUE TO THEN-UNKNOWN CAUSES. THE PIPELINE WAS OPERATING AT 815 PSIG AT THE TIME OF THE INCIDENT, WITH AN ESTABLISHED MAXIMUM ALLOWABLE OPERATING PRESSURE (MAOP) OF 865 PSIG. THERE WAS NO FIRE, EXPLOSION, INJURY/DEATH, OR MAJOR PRIVATE PROPERTY DAMAGE ASSOCIATED WITH THE RUPTURE. THE RUPTURE WAS IDENTIFIED BY TALLGRASS GAS CONTROLER USING SCADA AT 20:03 WHEN PRESSURE DROPPED FROM 815 TO 545 PSIG AT THE HENRY-TORRINGTON STATE LINE CHECK METER. GAS CONTROL RECEIVED A CALL AT 20:09 FROM A SOURCEGAS EMPLOYEE WHO STATED THE 12"" LINGLE TO MITCHELL PIPELINE HAD RUPTURED. AT 20:15 THE AREA SUPERVISOR WAS CONTACTED AND CONFIRMED THAT A LOCAL OPERATOR WAS ON THE SCENE. HE BEGAN SHUTTING IN THE SEGMENT VIA MAINLINE VALVES. GAS CONTOL CLOSED THE GUERNSEY TO HENRY/TORRINGTON FEED AT THE GUERNSEY COMPRESSOR STATION AT 20:18. AT 20:24 THE DOWNSTREAM MAINLINE VALVE NEAR HENRY HAD BEEN CLOSED. AT 20:30, THE UPSTREAM MANINLINE VALVE NEAR TORRINGTON WAS CLOSED. FIELD OPERATIONS SUPERVISED AN INTENTIONAL AND CONTROLLED BLOWDOWN OF THE LOCAL SEGMENT UNTIL IT WAS SAFE TO APPROACH THE RUPTURE SITE TO BEGIN INVESTIGATION. FIELD INVESTIGATION REVEALED A CATASTROPHIC RUPTURE OF A PIPE SECTION APPROXIMATELY 10 FEET IN LENGTH, WITH COMPLETE SEPARATION OF THE RUPTURED SECTION FROM THE PIPELINE. THE PIPE (API-5L X42, ERW, MANUFACTURED IN 1963 BY REPUBLIC STEEL) WAS SENT TO A METALLURGICAL FIRM FOR STUDY.