ANR PIPELINE CO — Gas transmission and gathering — incident on 2015-05-15

Gas transmission and gathering incident. Reported cause: CORROSION FAILURE. Reported consequences: 0 fatalities, 0 injuries, 1 NATURAL GAS released, $375,000 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: 20150078.

Operator ID: 405.

Reported incident date: 5/15/2015 16:25.

Cause detail: EXTERNAL CORROSION

Cause detail: ON 15 MAY 2015 AT 16:25 CDT, A LEAK ON TC OFFSHORE (TCO) PIPELINE RISER WAS REPORTED BY THE OWNER OF THE PLATFORM LOCATED IN OUTER CONTINENTAL SHELF SHIP EUGENE ISLAND BLOCK 259 (EI259). AN AUDIBLE RELEASE OF GAS WAS DISCOVERED BY THE THIRD PARTY PRODUCER EMANATING FROM BENEATH A RISER CLAMP AND REPORTED TO TRANSCANADA/ANR PIPELINE COMPANY (ANR), OPERATOR FOR TCO. THE LEAK WAS LOCATED ABOVE THE WATER LINE ON THE PIPELINE RISER NEAR MILEPOST 0 ON THE 757 12' TRANSMISSION LINE ON A PLATFORM OWNED BY ENERGY XXI (28.45374, -91.456405). THE INCIDENT WAS REPORTED TO THE NATIONAL RESPONSE CENTER ON 15 MAY 2015 AT 18:08 CDT (REPORT #116658). FOLLOWING THE REPORT OF THE INCIDENT TO THE NATIONAL RESPONSE CENTER, ANR MAINTAINED CONTACT AND UPDATED U.S. COAST GUARD, BSEE, AND PHMSA. FOLLOWING THE DISCOVERY LEAK, THE 10.83 MILE PIPELINE SECTION WAS ISOLATED AT 09:30 CDT ON 16 MAY 2015 FROM EI259 TO EUGENE ISLAND 231. THE PIPELINE WAS ATTEMPTED TO BE BLOWN DOWN BEGINNING ON 16 MAY, WHEN PROCESS WATER WAS DISCOVERED IN THE PIPELINE. DURING THE BLOW DOWN, THE WATER FROM THE PIPELINE WAS PROCESSED BY A VENT SCRUBBER AND STORED IN TANKS AT THE PLATFORM ON EI259. ADDITIONALLY, A GAS BUSTER WAS USED TO FURTHER REDUCE THE PRESSURE ON THE PIPELINE AND REMOVE PROCESS WATER. ON 18 MAY 2015 AT 06:45, A PIPELINE TECHNICIAN OBSERVED THE PRESENCE OF SHEEN ON THE SURFACE OF THE WATER FROM LEAK LOCATION. AN ADDITIONAL NRC REPORT WAS FILED ON 18 MAY 2015 AT (NRC REPORT #1116799). LOCATION AND AREA OF THE SHEEN WAS MONITORED UNTIL THE LEAKING CEASED ON 21 MAY 2015. ON 24 MAY 2015, VENTING WAS COMPLETED, THE LINE WAS PURGED WITH NITROGEN, AND PREPARATIONS WERE MADE TO REPAIR THE LINE. FOLLOWING VENTING OF THE LINE, THE CLAMP ON THE PIPELINE RISER WAS REMOVED AND NON-DESTRUCTIVE EXAMINATION (MAG PARTICLE) WAS PERFORMED ON THE LEAK AREA. ANALYSIS DETERMINED THAT THE LEAK WAS CAUSED BY PITTING ATTRIBUTED TO EXTERNAL CORROSION. ON 25 MAY 2015, AN EXTERNAL WELD-ON SPLIT SLEEVE REPAIR CLAMP WAS SUCCESSFULLY INSTALLED ONTO THE PIPELINE TO REPAIR THE LEAK LOCATION. THE PIPELINE WAS RE-COATED WITH CARBO-MASTIC EPOXY PAINT AND THE RISER CLAMP WAS REINSTALLED. IN SEPTEMBER 2015, THE PIPELINE WAS PLACE RETURNED TO SERVICE

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: CORROSION — EXTERNAL.

PHMSA indexed costs: $383,104 reported total cost, $195,639.332 in 1984 dollars, $472,520.508 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.