COLUMBIA GULF TRANSMISSION, LLC — Gas transmission and gathering — incident on 2014-05-10

Gas transmission and gathering incident in CORINTH, ALCORN County, MS. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 25228 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: 20140062.

Operator ID: 2620.

Reported incident date: 5/10/2014 9:14.

Location detail: 5SG-33

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: ON MAY 10TH, 2014, A COLUMBIA GULF TRANSMISSION, LLC (COLUMBIA) CORINTH COMPRESSOR STATION (CS) PERSONNEL ARRIVED ON SITE AND NOTICED THAT A RELIEF VALVE (RV) WAS UNINTENTIONALLY RELIEVING A MINUTE AMOUNT OF NATURAL GAS INTO ATMOSPHERE. THE COLUMBIA PERSONNEL INVESTIGATED THE AREA AND ISOLATED THE RV FOR FURTHER INVESTIGATION INTO THE REASON BEHIND THIS UNINTENDED RELEASE. AFTER ENGAGING ENGINEERING PERSONNEL INTO THE INVESTIGATION, IT WAS IDENTIFIED THAT AT THE TIME THE CS WAS REMOTELY SHUTDOWN, ALL BLOWDOWN VALVES FUNCTIONED AS THEY WERE DESIGNED TO. HOWEVER THE SUBJECT RV WAS MODULATING THE FLOW AND ACTING SIMILAR TO A REGULATOR VALVE RATHER THAN A RV. IT WAS IDENTIFIED THAT THE PRESSURE DIFFERENTIAL WAS SO MINUTE TO AN EXTENT THAT IT ALLOWED TO UNSEAT THE VALVE AND UNINTENTIONALLY RELEASING MATERIAL INTO ATMOSPHERE. THE PILOT CONTROL PRESSURE WAS NOT REQUIRED TO BE INSTALLED ON THE UPSTREAM SIDE OF THE INSTALLATION OF THE CS UNIT SUCTION HEADER. HENCE, IT WAS RELOCATED AND A RECONFIGURATION TO SUCH INSTALLATION WAS EXECUTED ALONG THIS FACILITY. FURTHERMORE, A RECOMMENDED APPROACH WAS SHARED AMONG OTHER CS WITH SIMILAR INSTALLATIONS TO INSPECT AND RELOCATE THE PILOT CONTROLS SENSORS TO AVOID SIMILAR SITUATIONS THAT MAY LEAD TO SIMILAR EVENTS.

PHMSA trend classification: significant incident, not serious.

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

PHMSA indexed costs: $119,076 reported total cost, $82,373.065 in 1984 dollars, $101,141.611 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.