DOMINION EAST OHIO — Gas transmission and gathering — incident on 2016-03-16

Gas transmission and gathering incident in PORT WASHINGTON, TUSCARAWAS County, OH. Reported cause: MATERIAL FAILURE OF PIPE OR WELD. Reported consequences: 0 fatalities, 0 injuries, 2.25 released, $96,805 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: 20160033.

Operator ID: 4060.

Reported incident date: 3/16/2016 14:30.

Location detail: 2424+00

Cause detail: DESIGN-, CONSTRUCTION-, INSTALLATION-, OR FABRICATION-RELATED

Cause detail: ON MARCH 16, 2016, DOMINION EMPLOYEES WERE NOTIFIED OF A POTENTIAL GAS LEAK IN PORT WASHINGTON, OHIO. DOMINION REPRESENTATIVES REPORTED TO THE AREA AND VERIFIED A LEAK. GAS CONTROL WAS NOTIFIED TO BEGIN PRESSURE REDUCTIONS IN THE LINE BEGINNING AT APPROXIMATELY 14:00, AND A BLOW DOWN PROCEDURE WAS COMPLETED AROUND 18:00 ON THE SAME DAY. THE SITE WAS EXCAVATED ON MARCH 17, 2016 AND THE LEAK WAS VALIDATED. THE LEAK WAS REPAIRED BY REPLACEMENT OF THE AFFECTED SECTION OF PIPE ON MARCH 19, 2016 AND THE LINE RESTORED TO SERVICE. THE SECTION OF PIPE THAT LEAKED WAS ANALYZED INTERNALLY DUE TO THE CIRCUMSTANTIAL SIMILARITIES FROM A RECENTLY REPORTED FAILURE, WHICH WAS SENT TO A 3RD PARTY LABORATORY FOR ANALYSIS. AFTER COMPLETION OF THE INTERNAL ANALYSIS, IT WAS CONFIRMED THAT THE CONDITIONS SURROUNDING THIS FAILURE ARE IDENTICAL. THE PREVIOUS FAILURE ANALYSIS DETERMINED THAT THE FAILURE WAS CAUSED BY DUCTILE OVERLOAD OF THE PIPE WALL AT THE WELD TOE. THE PRIMARY FACTOR TO THE FAILURE WAS SETTLEMENT OF THE BRANCH CONNECTION DUE TO IMPROPER SUPPORT. THE SETTLEMENT CAUSED BENDING STRESSES IN THE CARRIER PIPE AT THE SADDLE REINFORCEMENT FILLET WELD WHICH RESULTED IN THE FORMATION OF A CRACK. THE GEOMETRY OF THE FILLET WELD THAT ATTACHED THE SADDLE REINFORCEMENT PAD TO THE CARRIER PIPE WAS ALSO A CONTRIBUTING FACTOR TO THE FAILURE. THE SADDLE THICKNESS WAS 2.5 TIMES THE THICKNESS OF THE CARRIER PIPE WHICH CONTRIBUTED TO A STRESS CONCENTRATION IN THE THINNER PIPE AT THE FILLET WELD TOE. UNDERCUT AT THE TOE OF THE FILLET WELD FURTHER CONCENTRATED THE STRESS AND CONTRIBUTED TO THE FORMATION OF A CRACK.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: MATERIAL FAILURE OF PIPE OR WELD — CONSTRUCTION, INSTALLATION OR FABRICATION-RELATED.

PHMSA indexed costs: $115,550 reported total cost, $65,286.624 in 1984 dollars, $142,709.949 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.