GAS TRANSMISSION NORTHWEST CORPORATION (GTN)
gas_transmission Incident — — June 1, 2012
Incident Information
| Incident Date | June 1, 2012 |
| Operator | GAS TRANSMISSION NORTHWEST CORPORATION (GTN) |
| Commodity | NATURAL GAS |
| Pipeline Type | gas_transmission |
Location
| State | |
| Coordinates | 48.96657, -116.17386 |
Cause
| Cause | INCORRECT OPERATION |
| Subcause | VALVE LEFT OR PLACED IN WRONG POSITION, BUT NOT RESULTING IN AN OVERPRESSURE |
Casualties
| Fatalities | 0 |
| Injuries | 0 |
Costs
| Property Damage | $0 |
| Emergency Response | $900 |
| Other Costs | $0 |
Location Map
Incident Narrative
ON JUNE 1ST AT APPROXIMATELY 0930 PDT, A COMMUNICATIONS FAILURE WITHIN THE STATION 3 PROGRAMMABLE LOGIC CONTROLLER (PLC) CAUSED A STATION EMERGENCY SHUTDOWN (ESD). THE STATION VALVES IMMEDIATELY ATTEMPTED TO GO TO THEIR FAIL-SAFE POSITIONS. THE STATION B LINE SUCTION VALVE (VALVE 15) FAILED TO CLOSE AND ALLOWED GAS TO VENT THROUGH THE STATION BLOWDOWN SILENCER FOR APPROXIMATELY 90 MINUTES. GAS CONTROL FIRST NOTED AN ESD AT THE STATION AND THEN OBSERVED INDICATIONS THAT THE STATION MAY NOT HAVE BLOWN DOWN PROPERLY AND THAT IT WAS POSSIBLE THAT GAS WAS CONTINUING TO VENT. GAS CONTROL NOTIFIED LOCAL PERSONNEL AT THE SANDPOINT OFFICE AND TWO TECHNICIANS WERE DISPATCHED TO INVESTIGATE. THE TECHNICIANS ARRIVED AT STATION 3 AT APPROXIMATELY 1100 PDT. THEY DETERMINED THAT GAS WAS VENTING OUT THE BLOWDOWN SILENCER AND THAT VALVE 15 HAD NOT CLOSED. POWER GAS WAS RESTORED TO VALVE 15 WHICH ALLOWED THE VALVE TO TRAVEL CLOSED AND STOP THE VENTING OF GAS.
About This Pipeline Incident
Pipeline incident data is reported to the Pipeline and Hazardous Materials Safety Administration (PHMSA). All significant incidents involving fatalities, injuries, or property damage over $50,000 must be reported.