MARATHON PIPE LINE LLC

Incident Narrative

ON 12/4/2021 AT 10:03 HRS. (MOUNTAIN TIME) PUMPS AT THE GISSLER STATION WENT DOWN ON THE LOW SUCTION. AT 10:04 HRS. MPL TOOK ACTIONS TO SHUT DOWN AND ISOLATE THE IMPACTED PIPELINE SEGMENT. AT 11:15 HRS. MPL RECEIVED A CALL FROM THE PUBLIC INDICATING A SUSPECTED RELEASE ON THE PIPELINE. AT 11:18 HRS. THE RELEASE WAS CONFIRMED BY AN MPL EMPLOYEE. THE PRODUCT RELEASED WAS ON A 6-INCH ISOBUTANE PIPELINE AT LAT. 32.80415, LONG. -104.45888. THE FAILURE OCCURRED WITHIN THE GISSLER - MP 14 BLOCK VALVE SECTION (AN 8-MILE SECTION) ALONG THE ARTESIA TO EL PASO PIPELINE. AN INITIAL CALL TO THE NRC WAS MADE AS PROVIDED IN PART B, AND A 48-HR NRC UPDATE (1323733), WAS COMPLETED ON DECEMBER 6, 2021 AT 10:52 HRS. A VAPOR CLOUD INITIALLY PREVENTED IMMEDIATE RESPONSE TO THE LOCATION. ONCE THE AREA WAS ISOLATED, AND IT WAS SAFE TO EXCAVATE, IT WAS DETERMINED THAT THE FAILURE WAS THE RESULT OF A LONGITUDINAL SEAM FAILURE ON THE PIPE. THE PIPE WAS SENT TO A LAB TO IDENTIFY THE SPECIFIC FAILURE MECHANISM. SUPPLEMENTAL UPDATE 3/30/2022: THE LAB ANALYSIS DETERMINED THAT THE RUPTURE WAS CAUSED BY CORROSION FATIGUE LIKELY FROM LACK OF FUSION ELECTRICAL RESISTANCE WELD (ERW) REGIONS LOCATED ON THE INSIDE OF THE PIPE. PART K CONTRIBUTING FACTORS, INTERNAL CORROSION, CORROSIVE COMMODITY - EXPLANATION THE METALLURGICAL ANALYSIS FURTHER INDICATED THAT CORROSION FATIGUE OCCURS WHEN MATERIAL EXPERIENCES CYCLIC LOADING WHILE EXPOSED TO A CORROSIVE ENVIRONMENT. EXPOSURE TO THE CORROSIVE ENVIRONMENT CAUSES A DECREASE IN THE FATIGUE RESISTANCE OF A COMPONENT AND RESULTS IN FATIGUE CRACK GROWTH AT LOWER CYCLIC STRESSES. THE AREA WITH LACK OF FUSION WAS SUBJECT TO THE CORROSIVE ELEMENTS IN THE PROCESS STREAM OVER ITS 62 YEARS OF SERVICE. ADDITIONALLY, THE LACK OF FUSION DEFECT ACTED AS A STRESS RISER FOR THE ACCUMULATION OF FATIGUE DAMAGE FROM PRESSURE CYCLING EVENTS DURING THE LONG SERVICE HISTORY. ALTHOUGH NO PRESSURE SPIKES WERE REPORTED AT THE TIME OF RUPTURE, CRACK ARREST LINES CONSISTENT WITH FATIGUE CRACK PROPAGATION WERE OBSERVED ON THE FRACTURE SURFACE. THE FINAL FRACTURE OCCURRED BY OVERLOAD OF THE REPAIR WELDED REGION. SUPPLEMENTAL UPDATE ALSO INCLUDES ADDITIONAL QUESTIONS FROM THE REV 3-2021 FORM UPDATE. 08/10/2022 SUPPLEMENTAL UPDATE: ADJUST CONFIRMED DISCOVERY TIME BASED ON WHEN NRC REPORTABILITY WAS DETERMINED.