WISCONSIN GAS CO — Gas distribution — incident on 2008-01-24

Gas distribution incident in HAYWARD, SAWYER County, WI. Reported cause: 20. Reported consequences: 0 fatalities, 0 injuries, $525,833 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: 20080036.

Operator ID: 22763.

Reported incident date: 1/24/2008.

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: ON THE MORNING OF JANUARY 24, 2008, WITH TEMPERATURES AROUND -24 DEGREES , WE ENERGIES EXPERIENCED CONSECUTIVE FAILURES OF A REGULATOR AND RELIEF VALVE AT ITS HAYWARD, WISCONSIN DISTRICT REGULATOR STATION LOCATED ON U.S. HWY. 63, SOUTH OF GEHRTS ROAD IN THE TOWN OF HAYWARD, WISCONSIN. THE FAILURES ULTIMATELY RESULTED IN A LITTLE MORE THAN 1,700 RESIDENTIAL, COMMERCIAL AND INDUSTRIAL CUSTOMERS WITHOUT NATURAL GAS SERVICE. THE MAKE-UP OF THE STATION CONSISTED OF TWO, FULL CAPACITY, PARALLEL RUNS, OF 2", TYPE FG-76-75 MOONEY REGULATORS. OVER PRESSURE PROTECTION FOR THE REGULATORS WAS PROVIDED BY A FISHER, TYPE 63EG, 6" RELIEF VALVE. THE STATION IS FED BY A 475 MAOP SYSTEM AD SUPPLIES THE COMMUNITY OF HAYWARD WITH A 60 PSIG DISTRIBUTION SYSTEM.AFTER REVIEW OF RECORDED DATA, INTERVIEWS WITH PERSONNEL INVOLVED AND EXAMINATION OF EQUIPMENT, THE FOLLOWING SEQUENCE OF EVENTS WAS DETERMINED TO HAVE OCCURRED. AT AROUND 5 AM ON THE MORNING OF THE FAILURE, THE PRIMARY REGULATOR RUN AT THE HAYWARD DISTRIBUTION REGULATION FACILITY BEGAN TO FAIL. THE DISTRIBUTION SYSTEM PRESSURE BEGAN TO INCREASE UNTIL THE PRESSURE RELIEF VALVE BEGAN TO RELIEVE AT APPROXIMATELY 5:30 AM. THE RELIEF VALVE CONTINUED TO RELIEVE BUT DID NOT RE-SEAT ITSELF WHEN THE PRESSURE GOT BACK DOWN TO 60 PSIG. WITH THE RELIEF VALVE CONTINUING TO RELIEVE, THE PRESSURE ON THE SYSTEM CONTINUED TO FALL AT WHICH POINT AT APPROXIMATELY 6:39 AM, CUSTOMERS BEGAN TO CONTACT WE ENERGIES THAT THEY WERE WITHOUT GAS. WE-ENERGIES GAS CONTROL CENTER HAD ALREADY RESPONDED TO A LOW PRESSURE ALARM RECEIVED AT 5:50 AM WITH THE DISPATCHING OF A FIRST RESPONDER. UPON ARRIVAL, THE FIRST RESPONDER STATED THAT THE RELIEF VALVE WAS BLOWING. KNOWING THAT CUSTOMERS WERE REPORTING NO GAS AND GAS CONTROL CONFIRMING ZERO PRESSURE, THE RESPONDER WAS INSTRUCTED TO SHUT THE STATION DOWN. THE PROCESS OF CHECKING THE STATION EQUIPMENT FOR THE CAUSE OF THE FAILURE BEGAN. THE STATION REGULATORS WERE DISMANTLED AND NEW RUBBER GOODS INSTALLED BY APPROXIMATELY 11 AM. A NEW RELIEF VALVE WAS SHIPPED TO THE SITE AND WAS INSTALLED BY APPROXIMATELY 3:30 PM. THE PRIMARY CAUSE OF REGULATION FAILURE WAS DETERMINED TO BE THE PASSAGE OF DUST/DEBRIS THROUGH THE STATION PLUGGING BOTH THE PRIMARY FILTER AND ERODING THE RUBBER PRODUCTS IN THE REGULATOR.ON JANUARY 30TH, 2008, TWO REPRESENTATIVES FROM THE FISHER COMPANY, MR. THOMAS STEMRICH, PIPELINE PROGRAM SAFETY MANAGER FROM THE PUBLIC SERVICE COMMISSION OF WISCONSIN AND REPRESENTATIVES OF WE ENERGIES INSPECTED THE FAILED RELIEF VALVE. THE INSPECTION REVEALED THAT A SIGNIFICANT AMOUNT OF PIPELINE DUST/DEBRIS WAS FOUND IN THE PILOTS. A SUMMARY OF THE INVESTIGATION WITH REPRESENTATIVES FROM THE FISHER RESULTED IN THE BELIEF BY FISHER AND WE ENERGIES PERSONNEL, THAT THE DEBRIS THAT GOT INTO THE PILOTS DID NOT ALLOW LOADING PRESSURE TO CLOSE THE MAIN BODY OF THE RELIEF.WE-ENERGIES AS OF THE DATE OF THIS REPORT HAS TAKEN THE FOLLOWING STEPS TO REDUCE THE POSSIBILITY OF A RE-OCCURRING FAILURE. A STATION FILTER WITH A 10 MICRON FILTERING CAPABILITY WAS INSTALLED AT THE INLET AT THE INLET OF THE STATION AND ANOTHER FILTER IN THE SUPPLY TO THE PILOT OF THE RELIEF VALVE. IN ADDITION, THE STATION REGULATION WAS REPLACED WITH AN OPERATOR-MONITOR CONFIGURATION SUPPORTED WITH A FULL CAPACITY RELIEF DEVICE. AN INCIDENT REVIEW WAS CONDUCTED TO REVIEW NOT ONLY THE FAILURE BUT OUR EMERGENCY RESPONSE PROCEDURES TO SAFELY AND EFFICIENTLY GET CUSTOMERS BACK ON SERVICE AS SOON AS POSSIBLE. A MUTUAL AID PROCESS WAS IMPLEMENTED DURING THIS OUTAGE WITH THE MAJORITY OF THE CUSTOMERS BACK ON SERVICE BEFORE MIDNIGHT THAT SAME DAY WITH ALL THE REMAINING TURNED BACK ON BY 10AM THE FOLLOWING DAY EXCEPT FOR A COUPLE "COULD NOT GET INS" REMAINING. ARRANGMENTS WERE MADE WITH THE LOCAL POLICE DEPARTMENT TO GAIN ACCESS TO THOSE REMAINING CUSTOMERS.THE MANUFACTURER OF THE RELIEF VAVLE CONTINUES TO REVIEW THE RELIEF FAILURE MODE. IF ANY CHANGES IN THEIR VIEW OF THE FAILURE ANALYSIS OCCURS, WE ENERGIES WILL FI LE AN AMENDED REPORT. OTHERWISE, THIS REPORT IS CONSIDERED A FINAL REPORT.

PHMSA trend classification: significant incident, not serious, not fire-first.

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

PHMSA indexed costs: $525,833 reported total cost, $292,426.218 in 1984 dollars, $717,056.512 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.