EXXONMOBIL PIPELINE COMPANY LLC

Incident Narrative

INCIDENT SUMMARY AND CONSEQUENCE: ON AUGUST 3, 2022, DURING NORMAL OPERATION, A 1"" NIPPLE ASSOCIATED WITH THE VALVE BODY THERMAL RELIEF SYSTEM, ON TOP OF THE MOV-508, SHEARED OFF. THE OPERATIONS SUPERVISOR FOUND THE LEAK DURING AN OPERATIONAL ROUND AND WAS ABLE TO SHUT DOWN AND ISOLATE THE DELAWARE CONNECTOR PIPELINE SYSTEM (DCPL) WITHIN MINUTES. FOLLOWING ISOLATION, EMPCO ENGINEERING CALCULATED THE ESTIMATED RELEASE VOLUME TO BE 9.3 BARRELS. THE VALVE BODY THERMAL RELIEF SYSTEM ON MOV-508 WAS REPLACED WITH STAINLESS-STEEL TUBING THAT IS LIGHTER AND LESS BRITTLE, AND BRACING WAS ADDED TO REDUCE FATIGUE STRESS FROM VIBRATION. PRIOR TO RESTARTING THE PIPELINE, EMPCO OPERATIONS AND ENGINEERING INSPECTED THE PIPELINE MANIFOLD FOR FITTINGS OF SIMILAR DESIGN AND MATERIALS. THESE FITTINGS WERE REPLACED. THE DCPL PIPELINE SYSTEM WAS RESTARTED AT APPROXIMATELY 21:30 ON 8/3/22. CLEANUP EFFORTS (ALL ON OPERATOR CONTROLLED PROPERTY): A VACUUM TRUCK WAS DEPLOYED, TO REMOVE ALL FREE STANDING OIL. ABSORBENT PADS WERE USED TO WIPE AND CLEAN ALL OIL FROM SURROUNDING PIPING. ALL CONTAMINATED SOIL WAS EXCAVATED AND PLACED IN ROLL OFF BINS THAT WERE PROFILED AND SENT TO AN APPROVED WASTE SITE. KEY INVESTIGATION FINDINGS: THE VALVE BODY THERMAL RELIEF SYSTEM ON TOP OF MOV-508 WAS THE PROPER MATERIAL (316 SS) AND INSTALLED ACCORDING TO DESIGN PRACTICES. THE INVESTIGATION TEAM IDENTIFIED THE PRIMARY CAUSE OF THE EQUIPMENT FAILURE TO BE FATIGUE DUE TO LOW STRESS AND HIGH CYCLE VIBRATION OF THE THERMAL RELIEF SYSTEM. OTHER FAILURE MODES WERE RULED OUT THROUGH LAB ANALYSIS. OPERATIONS AND ENGINEERING TOOK PROACTIVE MEASURES TO INSTALL ADDITIONAL BRACING TO MINIMIZE VIBRATION FATIGUE OF OTHER DCPL MANIFOLD VALVE BODY RELIEF SYSTEMS WITH SMALL BORE PIPING. PREVENTING REOCCURRENCE: EMPCO HAS MITIGATED FAILURE RISK WITH OTHER SMALL BORE PIPING THAT IS ON THE DCPL MANIFOLD BY: -MODIFIED CONNECTIONS TO CREATE MORE EFFICIENT ROUTING, REMOVING EXCESS WEIGHT AND REDUCING VIBRATION -INSTALLED BRACING ON TUBING/SMALL BORE CONNECTIONS TO PROVIDE TWO PLANE VIBRATION REDUCTION SUPPLEMENTAL FINAL UPDATES: - UPDATED THE COST TOTALS FOR THE ACCIDENT. - UPDATED TYPO ERRORS IN THE PART H NARRATIVE PER PHMSA EMAIL.