SOUTHERN NATURAL GAS CO — Gas transmission and gathering — incident on 2017-11-09

Gas transmission and gathering incident in WHITE CASTLE, IBERVILLE County, LA. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 11600 NATURAL GAS released, $400 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: 20170119.

Operator ID: 18516.

Reported incident date: 11/9/2017 17:04.

Location detail: 30.725

Cause detail: THREADED CONNECTION/COUPLING FAILURE

Cause detail: AT 5:04PM ENGINE #10 RELIEF VALVE BEGAN VENTING GAS DUE TO A BROKEN SENSING LINE. THE UNIT WAS EMERGENCY STOPPED AT 5:23PM. THE TOTAL AMOUNT OF UNINTENTIONALLY NATURAL GAS RELEASED WAS 11,600 MCF. THE INITIAL INVESTIGATION SHOWED THAT THE 1/4-INCH PIPE NIPPLE ON THE RELIEF VALVE PILOT TEST PORT BROKE CAUSING THE RELIEF VALVE TO VENT. UPON FURTHER INVESTIGATION IT WAS DETERMINED THAT VIBRATION AND THE WEIGHT OF THE TEST ASSEMBLY MAY HAVE CONTRIBUTED TO THE FAILURE OF THE PIPE NIPPLE. THE NIPPLE WAS REPLACED WITH A MALE X FEMALE THREAD VALVE AND THE ENGINE WAS RETURNED TO SERVICE. THE PIR IS BASED ON THE LARGEST DIAMETER PIPE INSIDE THE COMPRESSOR BUILDING, NOT THE NIPPLE THAT FAILED.

PHMSA trend classification: not significant, not serious.

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

PHMSA indexed costs: $38,653 reported total cost, $36,517.486 in 1984 dollars, $45,079.371 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.