TRANSCONTINENTAL GAS PIPE LINE COMPANY — Gas transmission and gathering — incident on 2012-08-20

Gas transmission and gathering incident in HOUMA, TERREBONNE County, LA. Reported cause: CORROSION FAILURE. Reported consequences: 0 fatalities, 0 injuries, 3971 NATURAL GAS released, $302,000 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: 20120093.

Operator ID: 19570.

Reported incident date: 8/20/2012 15:25.

Location detail: 1.02

Cause detail: INTERNAL CORROSION

Cause detail: WHILE PERFORMING ARIEL PATROLS, BUBBLES WERE SPOTTED ON A TRANSCO ROW, WHERE TRANSCO OPERATES 4 PIPELINES. IMMEDIATLEY, THE NRC WAS CONTACTED ALONG WITH THE LOUISIANA STATE POLICE. TRANSCO OPERATORS HAVE ISOLATED THE LINE. THE CURRENT STATUS OF THE INCIDENT INVESTIGATION IS IN THE PRELIMINARY STAGE. THIS REPORT WILL BE UPDATED AS MORE DATA IS RECIEVED. SUPLEMENTAL LEAK REPORT UPDATE: - ON 9/27/2012 THE LEAK WAS INVESTIGATED THE LEAK WAS LOCATED ON A PIPELINE LOCATED IN A INLET TO THE GOM. - DIVERS EXPOSED THE LINE AND REMOVED EXTERNAL COATING (MASTIC AND CONCRETE). - WE IDENTIFIED AN ISOLATED PINHOLE LEAK AT THE SIX O'CLOCK POSITION IN A GIRTH WELD, - WE THEN REMOVED COATING AND CLEANED PIPE 3' ON BOTH SIDES OF THE GIRTH WELD - THE PIPE WAS VISUALLY INSPECTED AND A UT INSPECTION OF LEAK AREA WAS ALSO PREFORMENED.THE INSPECTIONS CONFIRMED AN ISOLATED PINHOLE LEAK. - THE DIVERS INSTALLED A MECHANICAL LEAK CLAMP. - THE ARE AFFECTED WAS RECOATED AND CHECKED FOR LEAKS. - THE LINE WAS THEN RETURNED TO SERVICE ON 10-1-2012. WE DETERMINED THAT THE CAUSE OF THE LEAK WAS AN ISOLATED PINHOLE LEAK AT 6'OCLOCK POSITION, ON A GIRTH WELD DUE TO INTERNAL CORROSION. THIS CONCLUSION IS CONSISTANT WITH TGPL'S FIELD TECHNICIANS EXPERIENCE WITH PREVIOUS INCIDENTS OF THIS NATURE.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: CORROSION — INTERNAL.

PHMSA indexed costs: $314,522 reported total cost, $169,520.461 in 1984 dollars, $404,563.883 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.