CONSUMERS ENERGY CO — Gas transmission and gathering — incident on 2012-08-28

Gas transmission and gathering incident in MANCHESTER, WASHTENAW County, MI. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 34597.47 NATURAL GAS released, $448 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20120097.

Operator ID: 2748.

Reported incident date: 8/28/2012 1:34.

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: AT APPROXIMATELY 1:34 AM, BLOWDOWN VALVE 613 AT FREEDOM COMPRESSOR STATION TRAVELED OPEN AND VENTED GAS TO ATMOSPHERE THROUGH THE STATION EMERGENCY SHUT-DOWN VENT FOR APPROXIMATELY 1 HOUR AND 23 MINUTES. IN TOTAL, 34 MMCF WAS VENTED TO ATMOSPHERE. AFT THE INCIDENT, THE VALVE OPERATOR MANUFACTURER'S REPRESENTATIVE (WILSON VALVE SPECIALTIES) WAS CONTACTED FOR TESTING METHODS. THE BIFFI 745 PILOT CONTROL VALVE WAS TESTED PER THESE VERBAL INSTRUCTIONS. NO DEFECTS WERE FOUND DURING TESTING, AND THE VALVE WAS PLACED BACK IN SERVICE. AN INVESTIGATION TEAM WAS SUBSEQUENTLY FORMED TO EVALUATE THE INCIDENT; THE TEAM CONVENED SEPTEMBER 5TH, 2012. AS A RESULT OF THIS INVESTIGATION, THE PILOT CONTROL VALVE WAS TO BE REMOVED AND SENT FOR FURTHER TESTING ON SEPTEMBER 7TH, 2012, AT WHICH POINT A SECOND VENTING INCIDENT OCCURRED (NRC REPORT #1023618). THE VENDOR (WILSON VALVE SPECIALTIES) WAS CONTACTED AGAIN BY INVESTIGATION TEAM MEMBERS TO DETERMINE WHETHER THEY WERE AWARE OF SUCH INCIDENTS ON SIMILAR BLOWDOWN VALVES. THEY INDICATED ONE SUCH VENTING INCIDENT IN WISCONSIN, AND INDICATED THAT A MODIFICATION HAD BEEN SUBSEQUENTLY MADE TO THE VALVE IN QUESTION TO HOUSE THE PILOT VALVE IN A WEATHER-TIGHT ENCLOSURE IN ORDER TO PROTECT IT FROM WEATHER CONDITIONS. NEW VALVE ASSEMBLIES, WITH WEATHER ENCLOSURES PROTECTING THE PILOT VALVE AS WELL AS THE CONTROLLER, WERE THEN ORDERED FOR VALVE 613 AND THREE OTHER SIMILAR VALES AT THE STATION. THESE ASSEMBLIES HAVE BEEN INSTALLED AND ALL VALVES APPEAR TO BE FUNCTIONING AS DESIGNED. TESTING OF THE REPLACED VALVE 613 ASSEMBLY BY WILSON HAS SINCE REVEALED A SMALL SEAL LEAK ON THE BIFFI 745 PILOT CONTROL VALVE, AS WELL AS PLUGGED VENTS, WHICH LIKELY CONTRIBUTED TO THE VENTING INCIDENTS.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — MALFUNCTION OF CONTROL/RELIEF EQUIPMENT.

PHMSA indexed costs: $203,516 reported total cost, $169,765.251 in 1984 dollars, $208,846.582 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.