NUSTAR PIPELINE OPERATING PARTNERSHIP L.P.

Incident Narrative

ON JANUARY 9, 2019 AT 2:20 PM, A NUSTAR EMPLOYEE WAS CHECKING VALVE 6-37 AND NOTICED A SMALL AREA NEARBY WHERE A PUDDLE WAS BUBBLING. AS A PRECAUTION, HE IMMEDIATELY BEGAN NOTIFICATION PROCEDURES, INCLUDING CALLING HIS MANAGER AND THE CONTROL CENTER. THE PIPELINE WAS SHUT DOWN AND THE SITE WAS MONITORED BY NUSTAR EMPLOYEES OVERNIGHT. PERIODIC GAS DETECTION RESULTS WERE DOCUMENTED TO ENSURE THE SITE REMAINED SAFE. THE NUSTAR MAINTENANCE CREW WAS MOBILIZED TO EXCAVATE AND DETERMINE THE CAUSE OF THE LEAK THE FOLLOWING MORNING. NUSTAR MAINTENANCE CREW BEGAN TO EXCAVATE ON JANUARY 10, 2019. UPON UNCOVERING THE PIPELINE, THE LEAK IS COMING FROM THE SIDE SEAM OF A STOPPLE TEE. THE ROOT CAUSE IS UNDETERMINED, SO THE PIPE WAS CUT OUT AND WAS SENT FOR METALLURGICAL LABORATORY FOR ANALYSIS. AN UPDATE CALL TO THE NRC WAS DONE ON 1/11/19 AT 14:20 AND RECEIVED NRC#1235058. THAT PORTION OF THE PIPE WAS REPLACED AND PUT BACK INTO SERVICE ON JANUARY 13, 2019. AMMONIA ENRICHED SOIL WAS RE-BURIED UNDER CLEAN SOIL UNTIL IT CAN BE EXCAVATED AND HAULED FOR LANDFARMING TO A NUSTAR LOCATION NEARBY. FROM METALLURGICAL REPORT: FATIGUE CRACKS INITIATED IN THE STOPPLE LONGITUDINAL WELD THAT HAD INADEQUATE PENETRATION. THE STOPPLE LONGITUDINAL WELDS CONTAINED LACK OF PENETRATION AND EXCESSIVE OFFSET (HI-LO). THE WELD PENETRATION WAS ONLY TWO-THIRDS THROUGH THE PIPE WALL AND DID NOT FUSE INTO THE BACKING PLATE. THE LACK OF PENETRATION RESULTED IN MULTIPLE FATIGUE CRACKS THAT DEVELOPED FROM THE NOTCH CREATED BY THE UNFUSED MATERIAL AT THE WELD ROOT.