EXXONMOBIL PIPELINE CO

Incident Narrative

TIMELINE: ON MONDAY, 8 NOVEMBER 2021 AT APPROXIMATELY 17:20, OPERATIONS DISPATCHED A CREW TO ALDINE STATION DUE TO UNRELATED ACTIVITIES AND DISCOVERED MOIST SOIL BETWEEN SLOP TANK #2238 AND TANK #2064. BACKGROUND INFORMATION: THE RELEASE OCCURRED ON THE 2"" SUMP DISCHARGE LINE JUST INSIDE OF THE DIKE WALL NEAR TANK #2238. THE PIPE WAS NPS 2, STANDARD WALL (0.154""), ERW OF UNKNOWN GRADE WITH COAL TAR COATING THAT WAS INSTALLED IN 1966. THE RELEASE OCCURRED AT THE 3 O'CLOCK LOCATION OF THE PIPE. THE PRESSURE IN THE SUMP DISCHARGE LINE AT THE TIME OF THE RELEASE WAS APPROXIMATELY 10 PSI DUE TO SLOP TANK HEAD PRESSURE. A TWO FOOT SECTION OF THE SUMP DISCHARGE LINE WHERE THE RELEASE OCCURRED WAS SECTIONED FROM THE LINE BY COLD CUT AND SENT TO A LABORATORY FOR EXAMINATION. RELEASE VOLUME CALCULATIONS: THE RELEASE VOLUME WAS CALCULATED BY ENGINEERING TO BE 57 BBL. BASED UPON SLOP TANK GAUGE DATA COLLECTED FROM SCADA. METALLURGICAL FAILURE MECHANISM: THE SUMP DISCHARGE LINE FAILED DUE TO INTERNAL CORROSION. THE FAILURE LIKELY INITIATED AS A PIT AND GREW UNTIL THROUGH WALL. THERE WAS NO EVIDENCE OF SIGNIFICANT EXTERNAL CORROSION. CATHODIC PROTECTION READINGS FOR THE AREA WERE CONFIRMED TO BE ADEQUATE. PREVENTION OF REOCCURRENCE: THIS SUMP DISCHARGE LINE IS OUT OF SERVICE TO BE REPLACED. 5/26/2022 - CREATED SUPPLEMENTAL FINAL REPORT WITH UPDATE FOR ADDITIONAL QUESTIONS AND UPDATED THE COSTS FOR THE RELEASE.