PHMSA Report 20190005 - EAST TENNESSEE NATURAL GAS, LLC (SPECTRA ENERGY PARTNERS, LP) — Gas transmission and gathering — incident on 2018-12-15 | Regulus

Gas transmission and gathering incident in PLEASANT SHADE, SMITH County, TN. Reported cause: MATERIAL FAILURE OF PIPE OR WELD. Reported consequences: 0 fatalities, 0 injuries, 46436 NATURAL GAS released, $2,865,200 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: 20190005.

Operator ID: 4070.

Reported incident date: 12/15/2018 14:09.

Location detail: MP 49.147

Cause detail: ENVIRONMENTAL CRACKING-RELATED

Cause detail: ORIGINAL REPORT: AT APPROXIMATELY 2:09 P.M. CST ON DECEMBER 15, 2018, ETNG'S 22-INCH DIAMETER LINE 3100-1 TRANSPORTING NATURAL GAS FROM DIXON SPRINGS COMPRESSOR STATION TO GAINESBORO COMPRESSOR STATION IN TENNESSEE FAILED AT MP 49.147. THE FAILED PIPE IS 22 INCH DIAMETER BY 9/32 INCH WALL THICKNESS, X-42. THE FAILURE RESULTED IN A RUPTURE WITHOUT FIRE. THERE WERE NO INJURIES OR FATALITIES. APPROXIMATELY 12 RESIDENTS EVACUATED UNTIL LOCAL EMERGENCY RESPONDERS OPENED ACCESS TO THE AREA. THE COMPRESSOR UNITS AT THE DIXON SPRINGS COMPRESSOR STATION WERE SHUTDOWN REMOTELY BY THE CONTROL ROOM AT 2:19 PM CST. THE ESD AT THE DIXON SPRING COMPRESSOR STATION WAS ACTIVATED AT 2:56 PM CST. THE MLV AT GAINESBORO COMPRESSOR STATION WAS CLOSED AT 2:47 PM CST FOLLOWED BY ESD ACTIVATION, COMPLETING INITIAL ISOLATION OF THE FAILURE SITE. ETNG PERSONNEL WERE ALSO DISPATCHED TO CLOSE THE MAINLINE BLOCK VALVES IMMEDIATELY DOWNSTREAM OF THE FAILURE SITE WHICH WAS CLOSED AT APPROXIMATELY 4:30 PM CST. ETNG PERSONNEL ARRIVED AT THE FAILURE SITE AT APPROXIMATELY 5:00 PM CST. THE NRC WAS NOTIFIED AT 3:50 PM CST, AS SOON AS LOCATION INFORMATION FOR THE FAILURE SITE WAS AVAILABLE. THE LINE WAS REPLACED, TESTED, AND SUBSEQUENTLY PUT IN-SERVICE ON DECEMBER 29, 2018. A 3RD PARTY METALLURGICAL INVESTIGATION IS ONGOING. THE ROOT CAUSE IS PENDING. SUPPLEMENTAL REPORT 09/27/2020 THE FAILURE HAS BEEN DETERMINED TO BE DUE TO A RELATIVELY SMALL 0.09' DEEP X 0.44' LONG HYDROGEN INDUCED CRACK IN THE ERW SEAM HEAT AFFECTED ZONE AT A LOCATION WHERE HYDROGEN EMBRITTLEMENT HAD REDUCED THE MATERIAL TOUGHNESS TO A LEVEL SUCH THAT THE PIPE COULD NOT WITHSTAND RUPTURE AT MOP.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: MATERIAL FAILURE OF PIPE OR WELD — ENVIRONMENTAL CRACKING-RELATED.

PHMSA indexed costs: $3,152,801 reported total cost, $1,591,626.682 in 1984 dollars, $3,703,363.011 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.