WILLIAMS FIELD SERVICES

Incident Narrative

INCIDENT DESCRIPTION: THE ECHO SPRINGS METER SKID IS JUST OUTSIDE THE PERIMETER FENCE OF THE WILLIAMS ECHO SPRINGS PROCESSING PLANT. AT 4:00 PM ON JANUARY 15, 2016, AN OPERATOR PERFORMED A SITE INSPECTION AND NO LEAK WAS OBSERVED. AT 5:30 PM A SMALL VAPOR CLOUD WAS NOTICED BY PLANT EMPLOYEES. THE FLOW TO THE METER SKID WAS STOPPED AND A CALL TO THE OPERATOR WAS MADE. THE OPERATOR RETURNED TO THE SITE AND ISOLATED THE TUBING AND REPAIRED THE DAMAGED PIECE. NORMAL OPERATIONS RESUMED AT 9:45 PM. CAUSES: - THE IMMEDIATE CAUSE OF THE RELEASE WAS A RUPTURE IN A 1/4"" SCHEDULE 10, TYPE 316L, STAINLESS STEEL TUBE DESIGNED TO RELIEVE PRODUCT PRESSURE FROM A THERMAL RELIEF VALVE. - THE LOCAL TEMPERATURE DURING THE DAY OF THE RUPTURE WAS APPROXIMATELY 20 DEGREES F. THE FOLLOWING CONCLUSIONS HAVE BEEN DETERMINED BASED ON THE RESULTS OF THE METALLURGICAL ANALYSIS AND INVESTIGATION: - A 1/2' ROOT VALVE DESIGNED TO BE OPEN DURING NORMAL OPERATION WAS NEARLY CLOSED, NOT ALLOWING WATER TO DRAIN FROM THE TUBING LEG. - THE SPLIT IN THE TUBING WAS DUE TO WATER FREEZING INSIDE THE TUBE CAUSING DUCTILE TEARING FROM INTERNAL PRESSURE GENERATED FROM THE EXPANSION OF WATER FREEZING INTO ICE. - WATER WAS MOST LIKELY INTRODUCED FROM A METER PROVER CONNECTION. - A WATER DRAW TEST WAS PREVIOUSLY PERFORMED ON THE PROVER AND RESIDUAL AMOUNTS OF WATER WERE NOT REMOVED. - THE 1/2"" ROOT VALVE CONNECTING TO THE THERMAL RELIEF WAS NOT IDENTIFIED AS A CRITICAL DEVICE THAT SHOULD BE LEFT OPEN DURING NORMAL OPERATION. CORRECTIVE ACTIONS: - THE WATER DRAW PROCEDURE WILL BE REVISED WITH SPECIFIC REQUIREMENTS FOR THE CONTRACTOR TO DRY THE PROVER LOOP AFTER THE WATER DRAW. - OPERATIONS WILL VERIFY NO FREE LIQUIDS ARE IN THE PROVER PRIOR TO INSTALLATION AFTER THE WATER DRAW TEST. THERMAL RELIEF VALVES AND CONNECTING ROOT VALVES WILL BE ADDED TO CRITICAL DEVICE LIST AT ALL METER AND BOOSTER STATIONS TO ENSURE THE ROOT VALVE IS OPEN DURING NORMAL OPERATION.