ROCKIES EXPRESS PIPELINE LLC

Incident Narrative

THE SENECA LATERAL, A PORTION OF THE ROCKIES EXPRESS PIPELINE, OWNED AND OPERATED BY TALLGRASS ENERGY (TALLGRASS), EXPERIENCED AN IN-SERVICE RUPTURE ON JANUARY 31, 2018 NEAR THE CITY OF SUMMERFIELD, OH AT 2:41 AM EASTERN LOCAL TIME. THE RUPTURE OCCURRED ALONG THE GIRTH WELD SEAM OF WELD ID BML-079 (STA.209+05.9). THE RUPTURED GIRTH WELD WAS A MAIN LINE WELD BETWEEN TWO 24-INCH OUTER DIAMETER (OD), 0.344-INCH WALL THICKNESS (WT), API 5L PSL 2 X70 GRADE PIPE. THE RUPTURE OCCURRED BETWEEN ROAD 513 AND ROAD 379 IN A FORESTED PORTION OF THE RIGHT OF WAY (ROW). THE MAXIMUM ALLOWABLE OPERATING PRESSURE (MAOP) OF THE LINE AT THIS LOCATION IS 1444 PSIG AND WAS OPERATING AT 1297 PSIG AT THE TIME OF RUPTURE. THE RUPTURE LOCATION IS APPROXIMATELY 4 MILES FROM THE MARK WEST PROCESSING PLANT AND 10 MILES FROM THE SENECA COMPRESSOR STATION. THE ENTIRE ROUTE IS CLASS 1 NON-HCA. THE LINE WAS NOT FLOWING ANY GAS AT THE TIME OF FAILURE. FIRE RESULTED FROM THE LINE FAILURE, THERE WERE NO INJURIES, AND THE ONLY KNOWN PROPERTY DAMAGE WAS TO SURROUNDING TREES. TALLGRASS CONDUCTED A ROOT CAUSE ANALYSIS (RCA) WITH THE GOALS OF IDENTIFYING CAUSAL FACTORS ASSOCIATED WITH THE RUPTURE EVENT AND DEVELOPING POTENTIAL PROACTIVE ACTION PLANS FOR ELIMINATING SIMILAR THREATS. THE RCA TEAM FOCUSED ON CAUSAL FACTORS ASSOCIATED WITH THE RUPTURE EVENT: ENVIRONMENTAL, MATERIALS, CONSTRUCTION/INSTALLATION AND INTEGRITY MANAGEMENT. SUBSEQUENT TO THE RCA DISCUSSION, AND WITH AGREEMENT FROM ALL PARTIES INVOLVED, IT WAS DEEMED THAT THE GIRTH WELD RUPTURE WAS AN OVERLOAD FAILURE CAUSED BY AXIAL STRESS DUE TO MOVEMENT OF THE PIPE THAT EXCEEDED THE CROSS-SECTIONAL TENSILE STRENGTH OF THE NET SECTION WELD ZONE SURROUNDING THE CRACK INITIATION LOCATION. THIS DETERMINATION IS SUPPORTED BY METALLURGICAL ANALYSIS, STRAIN CAPACITY EVALUATION AND GEOTECHNICAL FINDINGS.