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Safety Recommendation Details

Safety Recommendation P-77-029
Details
Synopsis: ON DECEMBER 7, 1976, A NATURAL GAS COMPRESSOR FAILED AND THEN EXPLODED AND BURNED AT AN EXXON GAS SYSTEM, INC., STATION NEAR ROBSTOWN, TEXAS. AN EMERGENCY SHUTDOWN SYSTEM WAS ACTIVATED, BUT FOUR AUTOMATED FIRE GATE VALVES DID NOT CLOSE. ANOTHER EMERGENCY CONTROL SYSTEM ALSO FAILED TO AUTOMATICALLY CLOSE THE SHUTOFF VALVES, LEADING TO TWO OF THE FIVE COMPRESSORS IN THE STATION. A SECOND EXPLOSION OCCURRED WITHIN THE BURNING BUILDING. THE FIRE KILLED ONE PERSON, INJURED TWO PERSONS, AND DESTROYED THREE ENGINE-DRIVEN COMPRESSORS AND THE COMPRESSOR BUILDING.
Recommendation: MAKE A TOTAL SYSTEMS REVIEW OF ELECTRIC, AIR, AND GAS-OPERATED EMERGENCY EQUIPMENT, WITH PARTICULAR EMPHASIS ON INTERCONNECTED AIR SYSTEMS AND BACKUP OR DUAL-FEED AIR SYSTEMS IN COMPRESSOR STATIONS.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Pipeline
Location: Robstown, TX, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA77MP005
Accident Reports:
Exxon Gas System, Inc., Natural Gas Explosion and Fire
Report #: PAR-77-03
Accident Date: 12/7/1976
Issue Date: 10/31/1977
Date Closed: 1/5/1979
Addressee(s) and Addressee Status: ExxonMobil Corporation (Closed--No Longer Applicable)
Keyword(s):

Safety Recommendation History
From: NTSB
To: ExxonMobil Corporation
Date: 1/5/1979
Response:

From: ExxonMobil Corporation
To: NTSB
Date: 12/20/1977
Response: EXXON GAS SYSTEM LTR: EXXON HAS INTERPRETED THIS TO APPLY TO THE COMPRESSOR BLOCK VALVE CONTROL SYSTEM RATHER THAN THE STATION ESD (FIRE GATE VALVE) CONTROL SYSTEM. THE BLOCK VALVE CONTROL SYSTEMS ARE OPERATIONAL RATHER THAN EMERGENCY SYSTEMS. FAIL-SAFE OPERATION AND BACK-UP POWER ARE NOT DEEMED NECESSARY FOR OPERATING SYSTEMS BY EXXON. FOUR NEW UNITS AT STATION I HAVE BEEN INSTALLED WITH FAIL-SAFE ACTUATORS. A POSITIVE EXPERIENCE WITH THIS SYSTEM WILL PROVIDE INFORMATION FOR FUTURE INSTALLATIONS. 5/12/78 - EXXON RESPONSE TO NTSB LETTER OF 4-27-78: EXXON HAS NEARLY COMPLETED AN EXTENSIVE REVIEW OF ALL EMERGENCY EQUIPMENT. THE REVIEW ADDRESSES THE RELIABILITY OF ALL PRIMARY POWER SOURCES (ELECTRIC, AIR, AND GAS) REQUIRED TO MAKE THE STATION EMERGENCY SYSTEMS FUNCTION PROPERLY. EXXON WILL PROVIDE REVIEW RESULTS AND SCHEDULE FOR IMPLEMENTING ANY NECESSARY MODIFICATION BY JULY 31, 1978. 7/31/78 - THE DETAILED SYSTEMS REVIEW OF EMERGENCY SYSTEM IS COMPLETE. IT HAS BEEN CONCLUDED BY EXXON THAT THE SYSTEM IS SATISFACTORY. THERE ARE NO INTERCONNECTED AIR SYSTEMS INVOLVED WITH THE EMERGENCY SYSTEM. THE BACK-UP POWER SOURCE IS DEFINED FOR EACH IDENTIFIED SEGMENT OF THE EMERGENCY SYSTEM. AN ATTACHMENT GIVES A SUMMARY OF FIRE GATE VALVE OPERATION.