MOBIL CORP

Incident Narrative

ON SEPTEMBER 9, 2010 THERE WAS A RELEASE OF APPROXIMATELY 15.46 GALLONS (0.37 BARRELS) OF GASOLINE FROM BREAKOUT TANK 3000 LOCATED AT THE COLONIAL TANK FARM. INSPECTIONS WERE PERFORMED (INTERNAL VISUAL, PT AND VACUUM BOX INSPECTIONS) TO DETERMINE THE FAILURE MODE OF THE TANK FLOOR. AFTER RECENT INSPECTION OF TANK 3000 SUMP AND SURROUNDING BOTTOM PLATE, A 2"" LINEAR THROUGH WALL CRACK AND TWO 1"" STRESS CRACKS WERE FOUND AT THE TOE OF AN ANGLE IRON BRACKET WELDED TO THE FLOOR. THE BRACKET WAS USED AS SUPPORT FOR A PERSONNEL BARRIER/VORTEX BREAKER OVER THE LARGE FLOOR SUMP. A 40' RADIUS OF ALL FLOOR LAP JOINTS AROUND THE SUMP WERE ABRASIVE BLASTED AND VACUUM BOX INSPECTED. ONLY DEFECTS NOTED ON THE LAP JOINT WELDS WERE ORIGINAL CONSTRUCTION DEFECTS (UNDERCUT, COLD ROLL, POROSITY). ALL FLOOR ATTACHMENT WELDS SURROUNDING THE SUMP WERE PT'ED. THE SAME ORIGINAL CONSTRUCTION DEFECTS WERE NOTED ON THESE WELDS AS WELL AS THE CRACK MENTIONED ABOVE. THE SUMP WELDS WERE PT'ED AND THE SAME CONSTRUCTION DEFECTS NOTED. ALL SUPPORTS WELDED DIRECTLY TO THE SUMP OR FLOOR PLATE THAT COULD BE REMOVED, WERE REMOVED AND PT'ED WITH NO MAJOR FINDINGS. REPAIRS WILL BE MADE PER ESTABLISHED REPAIR PLAN PRIOR TO PUUTING TANK BACK IN SERVICE.