DOMINION TRANSMISSION, INC — Gas transmission and gathering — incident on 2013-06-10

Gas transmission and gathering incident in CHAMBERSBURG, FRANKLIN County, PA. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 23856 released, $350,000 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: 20130060.

Operator ID: 2714.

Reported incident date: 6/10/2013 6:10.

Cause detail: FAILURE OF EQUIPMENT BODY (EXCEPT COMPRESSOR), VESSEL PLATE, OR OTHER MATERIAL

Cause detail: A REVIEW OF THE CHAMBERSBURG SILENCER DAMAGE APPEARS TO HAVE OCCURRED FROM FATIGUE THAT LIKELY HAD EXISTED FOR QUITE SOME TIME. THE HISTORY OF THIS UNIT INDICATES THAT DAMAGE OCCURRED DURING COMMISSIONING OF THIS UNIT IN 1996 THAT LIKELY TOOK A SLUG OF HYDRO-TEST WATER AND PROBABLY CRACKED/DAMAGED THE INTERNAL 44" DIAMETER FORMED & DISHED HEAD. REPAIRS TO THE UPPER SECTION WERE REPAIRED AND THE ORIFICE PLATE WAS REDESIGNED/REPLACED AT THIS SAME TIME, BUT NO DAMAGE WAS IDENTIFIED TO THE LOWER SECTION. THE SILENCER'S CURRENT DESIGN HAS THE DISHED HEAD ABSORBING THE MAJORITY OF THE DISCHARGE GAS FORCES. THE DISHED HEAD FAILED DURING THE 6/10/2013 VENTING EVENT CAUSING THE ENTIRE EASTERN WALL OF THE VESSEL TO FAIL. THIS ALLOWED ALL THE GAS TO VENT OUT THE SIDE OF THE SILENCER UNIT.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — FAILURE OF EQUIPMENT BODY.

PHMSA indexed costs: $455,000 reported total cost, $265,145.292 in 1984 dollars, $551,020.697 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.