KATY STORAGE & TRANSPORTATION LP

Incident Narrative

ON DECEMBER 23, 2014, AT 10:46 AM, THE ENSTOR KATY GAS STORAGE FACILITY WAS ON INJECTION MODE USING TWO COMPRESSORS TO INJECT NATURAL GAS INTO THE RESERVOIR VIA 3 STORAGE WELLS AND 2 COMPRESSORS. ENSTOR PERSONNEL WERE PERFORMING MAINTENANCE ON THE PLC WHEN A LINE OF LOGIC (WHICH CONTAINED A TYPO) WAS SAVED TO THE NEW MASTER CONTROL CENTER (MCC) PLC. THIS CAUSED A PLC FAULT WHICH IN TURN CAUSED THE FACILITY TO ESD, AS DESIGNED. THIS ESD CORRECTLY ACTED TO FULLY BLOCK AND BLEED AND FLARE-TO-VENT, HOWEVER A CONTROL VALVE ON THE VENT SIDE FAILED TO OPEN CAUSING AN OVERPRESSURE EVENT WHICH RELIEVED VIA A PRESSURE RELIEF VALVE, AS DESIGNED. ENSTOR RESPONDED TO PUBLIC INQUIRIES REGARDING THE GAS RELEASE AND RESULTING NOISE. THESE CALLS WERE FROM THE PUBLIC, REGULATORS AND FIRST RESPONDERS. CALLS REPORTING SMOKE AND FIRE WERE EXPLAINED TO BE ONLY LOUD NOISE, DUST AND DEBRIS FROM THE PSV LINE. A PLANT INVESTIGATION PROCESS WAS INITIATED AND COMPLETED. THE ORIGINAL CAUSE WAS DETERMINED TO BE A FAULT IN THE PLC. UPON INVESTIGATING WHY THE FLARE/VENT LINE HAD NOT RELEASED, IT WAS DISCOVERED THAT THE VENT BLOCK VALVE HAD FAILED TO OPEN CAUSED BY A FAULTY VERSA VALVE (NV-105B). THE FAULT WAS IMMEDIATELY CLEARED AND CORRECTED IN THE PLC WITH CORRECT LOGIC, AND THE VERSA VALVE WAS REPLACED. THIS EVENT DOES NOT MEET THE INCIDENT REPORTING REQUIREMENTS AS DEFINED IN 49 CFR 191.3.1(I), 191.3.1(II), 191.3.1(III), OR 191.3. THIS INCIDENT REPORT HAS BEEN COMPLETED AND SUBMITTED AT THE REQUEST OF PHMSA SOUTHWEST REGION DUE TO A CALL FROM A LOCAL RESIDENT WHO LIVES CLOSE TO THE KATY GAS STORAGE FACILITY. THE TOTAL RELEASE TIME WAS APPROXIMATELY 40 SECONDS WITH AN ESTIMATED RELEASE VOLUME OF 197,000 SCF OF NATURAL GAS.