DTE GAS COMPANY

Incident Narrative

ON FEBRUARY 27, 2014, AT 01:30 A DTE GAS OPERATOR AT BELLE RIVER MILLS (BRM) COMPRESSOR STATION RECEIVED A HIGH DIFFERENTIAL PRESSURE ALARM FOR THE PARTICULATE FILTERS ON THE GLYCOL REGENERATION SKID AND A PLANT SHUTDOWN INDICATION AT THE REMOTE COLUMBUS DEHYDRATION PLANT. AT 02:00, THE BRM OPERATOR DIRECTED A TRANSMISSION TECH TO REPORT TO COLUMBUS COMPRESSOR STATION(CCS)TO INVESTIGATE AND CORRECT THE CAUSE OF THE SHUTDOWN, AND THE HIGH DIFFERENTIAL FOR THE PARTICULATE FILTERS. TECH ARRIVED AT THE CCS AT 02:45. TECH DETERMINED THE PARTICULATE FILTERS ON THE GLYCOL SKID AT THE DEHYDRATION PLANT WERE PLUGGED (CAUSE NOT CLEAR AT THE TIME BUT ASSUMED TO BE BY SALT) CAUSING THE INCREASE IN PRESSURE DIFFERENTIAL. TECH NOTICED THAT THE LOCAL CONTROL PANEL INDICATED THE CAUSE OF PLANT SHUTDOWN TO BE HIGH LIQUID LEVEL IN THE FLASH TANK. TECH DRAINED THE CAGE FOR THE FLASH TANK LEVEL SWITCH TO RESET THE SWITCH AND THIS CAUSED THE PUMPS TO RESTART AUTOMATICALLY IN ACCORDANCE WITH THE CONTROL LOGIC FOR THE PLANT. TECH PROCEEDED IN ACCORDANCE WITH NORMAL PROCEDURE TO BYPASS AND DRAIN THE FILTER CASING TO REMOVE AND REPLACE THE FILTER ELEMENTS. WHILE CHANGING THE FILTERS, TECH HEARD THE LIQUID LEVEL CONTROL VALVE ON CONTACTOR A GO WIDE OPEN. TECH OBSERVED A HIGH LEVEL OF GLYCOL IN THE CONTACTOR SIGHT GLASS. TO SHUT OFF THE FLOW OF GLYCOL TO CONTACTOR A, THE TECH OPENED THE PUMP BYPASS VALVE. THE PUMPS STARTED CAVITATING, SO THE TECH OPENED ALL PUMP BYPASS VALVES WHICH IS STANDARD PROCEDURE WHEN PUMP CAVITATION OCCURS. THE TECH OBSERVED THE LEVEL OF GLYCOL IN THE REBOILER WAS HIGH. AT THIS SAME INSTANT, THE TECH OBSERVED THE EMISSION CONTROL SYSTEM (ECS) FLARE STACK IGNITE WITH A LARGE FLAME. TECH ATTEMPTED TO OPEN THE REBOILER DRAIN VALVE TO DRAIN GLYCOL FROM THE REBOILER TO THE SURGE TANK AND STABILIZE LEVELS IN THE SYSTEM.TECH THEN HEARD THE CREAKING NOISE OF WHAT APPEARED TO BE EXPANDING PIPE AND IMMEDIATELY EVACUATED THE BUILDING. TECH CONTACTED THE BRM OPERATORS TO INFORM THEM OF THE FIRE AND TO DISCONTINUE FLOW THROUGH THE CCS. AFTER THE TECH LEFT THE BUILDING THE SIGHT GLASS ON THE REBOILER BROKE SPILLING 1200 GALLONS OF GLYCOL IN THE BUILDING. TECH DID NOT ACTIVATE THE MANUAL PULL STATION FOR THE SAFETY SHUTDOWN SYSTEM (SSD) FOR THE DEHYDRATION PLANT SINCE THE GAS RELIEF STACKS WERE IN CLOSE PROXIMITY TO THE FIRE IN THE ECS FLARE STACK. INSTEAD,THE TECH MANUALLY OPENED THE CONTACTOR BLOW-DOWN VALVES TO EVACUATE GAS FROM THE PLANT BUILDING AND DIRECT THE GAS TO THE BLOW-DOWN SILENCER AT A SAFE DISTANCE FROM THE FIRE. THE BLOW-DOWN OF CONTACTOR A AND THE COMPRESSOR FUEL GAS SYSTEM WAS FOLLOWED BY THE BLOW-DOWN OF CONTACTOR B AT APPROXIMATELY 04:00. ADDITIONAL TECHNICIANS ARRIVED AT THE CCS AT APPROXIMATELY 04:00 AND 04:30. SUPERVISOR ARRIVED AT 05:30. TEAM ATTEMPTED TO USE THE 150# FIRE EXTINGUISHER TO QUENCH THE FIRE ON TOP OF THE FLARE STACK WITHOUT SUCCESS. THE FIRE IN THE ECS FLARE STAKE CONTINUED TO BURN, AND THE TECHS OBSERVED RED LIGHT FOR LEL ALARM AND REALIZED THE CONCENTRATION OF GAS WAS BUILDING UP INSIDE THE DEHYDRATION BUILDING. THE TECHS AND THE SUPERVISOR WERE UNABLE TO DETERMINE THE SOURCE OF THE LEAKING GAS INSIDE THE BUILDING SINCE THE BUILDING WAS FILLED WITH STEAM FROM THE SPILLED GLYCOL. ONCE THE GLYCOL COOLED, THE TECHS ENTERED THE BUILDING AND OBSERVED GAS WAS LEAKING AT THE BROKEN SIGHT GLASS ON THE REBOILER. INITIALLY THE TECHS AND SUPERVISOR BELIEVED THAT THE SOURCE OF FUEL TO THE ECS WAS GLYCOL AND HYDROCARBON AND NOT NATURAL GAS. THE TEAM FOUND OUT IT WAS NATURAL GAS THAT WAS FEEDING THE FIRE WHEN THEY TURNED OFF THE VALVES TO THE SIGHT GLASS ON THE REBOILER AND THE FLAME OUTSIDE ON THE OUTSIDE ON THE ECS FLARE INCREASED. UPON OPENING THE VALVES THE ECS FLAME DECREASED. THE TEAM THEN DETERMINED THE GAS WAS COMING THROUGH THE CHECK VALVES FROM THE CONTACTORS AND PUMPS OUT TO THE ECS.THEY SHUT THE MANUAL VALVES DOWNSTREAM OF THE CHECK VALVES AT CONTACTORS A&B AND THE FLAME TO THE ECS EXTINGUISHED AT 07:30.