ANR PIPELINE CO

Incident Narrative

A ROOT CAUSE FAILURE ANALYSIS (RCFA) FINAL REPORT, WHICH INCORPORATED THE FINDINGS FROM THE MECHANICAL AND METALLURGICAL TESTING REPORT SUMMARIZED THE EVENT AS, ""... A RUPTURE OF FACILITY PIPING ON THE SHELL SIDE OF THE GAS-GAS HEAT EXCHANGER (E-2053) LEADING TO THE EJECTION OF PROCESS PIPING AS WELL AS THE RELEASE OF NATURAL GAS TO THE ENVIRONMENT. CAUSAL FACTORS WERE RECOGNIZED FOR THE EVENT SEQUENCES PERTAINING TO (1) A NATURAL GAS LEAK FROM THE HIGH PRESSURE INJECTION HEADER TO LOWER PRESSURE PROCESS PIPING THROUGH ISOLATION VALVE XV-2070 AND XV-2071 AND (2) INADEQUATE SAFETY SYSTEMS IN THE SHELL SIDE OF THE HEAT EXCHANGER LOOP TO PREVENT RUPTURE OF THE LOWER MAOP PIPING."" METALLURGICAL LAB COMPLETED THE FAILURE ANALYSIS OF THE FRACTURED PIPING AND CONCLUDED THAT THE RUPTURE OF THE SHELL SIDE PIPING WAS CAUSED BY DUCTILE OVERLOAD FROM PIPE OVER-PRESSURIZATION. CAUSAL FACTORS WERE IDENTIFIED AS: LEAKING ISOLATION VALVES; INADEQUATE DESIGN-NO OVERPRESSURE PROTECTION OR ALARMS; NO POSITIVE ISOLATION OF SHELL SIDE LOOP. BASED ON THE RCFA, RECOMMENDATIONS AND POTENTIAL IMPROVEMENT OPPORTUNITIES IDENTIFIED, CORRECTIVE ACTIONS HAVE BEEN ASSIGNED TO ADDRESS EACH CONTRIBUTING FACTOR.