ENABLE GAS TRANSMISSION, LLC — Gas transmission and gathering — incident on 2017-11-22

Gas transmission and gathering incident in NOEL, MCDONALD County, MO. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 21095 NATURAL GAS released, $0 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: 20170121.

Operator ID: 602.

Reported incident date: 11/22/2017 5:21.

Location detail: NA

Cause detail: THREADED CONNECTION/COUPLING FAILURE

Cause detail: DURING THE 06:00 SHIFT CHANGE ON 11/22/17, ENABLE GAS TRANSMISSION SYSTEM CONTROL BECAME AWARE OF AN UNUSUAL SITUATION WITH LINE OM-1. SYSTEM CONTROL DID NOT RECEIVE ANY ALERTS, SAFETY RELATED ALARMS, OR RATE OF CHANGE ALARMS TO NOTIFY THEM OF THE SITUATION BUT DID NOTICE AN INCREASE IN FLOW RATE INTO LINE OM-1 AND A DECREASE IN DISCHARGE PRESSURE AT DUNN STATION. SYSTEM CONTROL IMMEDIATELY DISPATCHED FIELD TECHNICIANS TO SURVEY LINE OM-1 TO INVESTIGATE THE SITUATION. AT APPROXIMATELY 06:44, A 911 OPERATOR CONTACTED SYSTEM CONTROL TO REPORT A LOUD NOISE, AND POSSIBLE GAS LEAK, NEAR HWY 90 NEAR NOEL, MISSOURI. AT 07:21, AN ENABLE FIELD TECHNICIAN DISCOVERED A BLOWDOWN VALVE RELEASING NATURAL GAS TO ATMOSPHERE AT THE JANE COMPRESSOR STATION. AFTER THE STATION WAS SECURED, SCADA DATA WAS CHECKED AND BY 08:01 THE ISSUE HAD BEEN CORRECTED. UPON INVESTIGATION, A VERSA VALVE ACTUATOR FOR THE BLOWDOWN VALVE FAILED OPEN DUE TO A LEAK IN THE PILOT TUBING. THE LOOSE FITTING WAS TIGHTENED ELIMINATING THE LEAK. THE REMAINING VALVE FITTINGS WERE CHECKED AT THE STATION FOR TIGHTNESS. ON THE MORNING OF 11/22/17 ENABLE MIDSTREAM REPORTED A POTENTIAL RELEASE TO THE NRC (NRC #1197895 07:13), AND FOLLOWED UP LATER WITH A LOCATION AND QUANTITY CHANGE (NRC# 1197919 12:17). THE 48 HOUR FOLLOW UP CALL WAS PLACED ON 11/24/17 (NRC# 1197992 07:10).

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — THREADED CONNECTION/COUPLING FAILURE.

PHMSA indexed costs: $68,576 reported total cost, $64,653.528 in 1984 dollars, $79,988.324 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.