TRANSCONTINENTAL GAS PIPE LINE COMPANY — Gas transmission and gathering — incident on 2014-03-18

Gas transmission and gathering incident. Reported cause: CORROSION FAILURE. Reported consequences: 0 fatalities, 0 injuries, 241 NATURAL GAS released, $175,000 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: 20140038.

Operator ID: 19570.

Reported incident date: 3/18/2014 14:50.

Cause detail: INTERNAL CORROSION

Cause detail: RCA : WE (TRANSCO) RECEIVED A CALL FROM PRODUCER (FIELDWOOD) AT APPROXIMATELY 2:50PM ON 3-18-14 REPORTING THAT THEY SPOTTED BUBBLES COMING FROM PLATFORM SS 182. A HELICOPTER IS DISPATCHED TO LEAK SITE AND THEY PLOT GIVEN COORDINATES. THE LEAK LOCATION IS VERY CONGESTED WITH PRODUCER GATHERING PIPELINES WHICH COMPLICATE OUR INVESTIGATION. WITH THE INFORMATION GATHERED WE DETERMINE THAT IT IS OUR 10" (SELA) OFFSHORE GATHERING LINE THAT COULD BE LEAKING. A DIVE BOAT IS DISPACHED TO THE LEAK LOCATION. MULTIPLE PRODUCER LINES ARE ISOLATED. 03-21-2014. EXAMINATION BY DIVERS IDENTIFIED AN ISOLATED PINHOLE LEAK AT THE 7 O'CLOCK POSITION ON THE 10" GATHERING LINE. THE ISOLATED PINHOLE LEAK WITH NO WALL LOSS IS CONFIRMED BY ULTRASONIC TEST READINGS . 03-22-2014 REPAIR CLAMP IS INSTALLED AND THE 10" GATHERING LINE IS PUT BACK INTO SERVICE. THIS OCCURRENCE SUPPORTS THE LEAK CAUSE IS DUE TO INTERNAL CORROSION; THIS CONCLUSION IS CONSISTENT WITH OUR EXPERIENCE WITH PREVIOUS INCIDENTS OF THIS NATURE. THE LINE IS UN-PIGGABLE, AND IS IN TWO-PHASE WET GAS GATHERING SERVICE. THE LINE IS TREATED WITH CHEMICAL INHIBITORS AND BIOCIDES THROUGH CONTINUOUS INJECTION AND BATCH TREATING. THIS LINE AND SEVERAL OTHERS COMINGLE FLOW TO OUR FACILITY AT MOSQUITO BAY, WHERE WE COLLECT SAMPLES AND MONITOR RESIDUALS. THE CHEMICAL INJECTION EQUIPMENT OPERATION AND CHEMICAL QUANTITIES ARE CHECKED MONTHLY BY OUR FIELD TECHNICIANS. THESE ACTIONS ARE CONSISTENT WITH OUR SOP 20.11.03, WILLIAMS GENERAL INTERNAL CORROSION POLICY

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: CORROSION — INTERNAL.

PHMSA indexed costs: $179,915 reported total cost, $91,737.337 in 1984 dollars, $223,857.869 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.