ANR PIPELINE CO — Gas transmission and gathering — incident on 2015-06-29

Gas transmission and gathering incident in Not Within a Municipality, OSCEOLA County, MI. Reported cause: MATERIAL FAILURE OF PIPE OR WELD. Reported consequences: 0 fatalities, 0 injuries, 16012 NATURAL GAS released, $3,684,600 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: 20150100.

Operator ID: 405.

Reported incident date: 6/29/2015 2:50.

Location detail: MP 3.8

Cause detail: ENVIRONMENTAL CRACKING-RELATED

Cause detail: ON JUNE 29TH, 2015, AT 2:50 AM EDT FAILURE OCCURRED AT APPROXIMATE MP 3.8 ON ANR PIPELINE COMPANY'S 8250 LINE PIPELINE NEAR REED CITY, MICHIGAN. THE PIPELINE, WHICH HAS AN MAOP OF 650 PSIG, IS 24-INCHES OD, X52 GRADE, WITH A NOMINAL WALL THICKNESS OF 0.250 INCHES. THE ELECTRONIC FLASH WELDED PIPE WAS MANUFACTURED BY AO SMITH AND INSTALLED IN 1950. FLOW IN THE PIPELINE IS SEASONALLY BI-DIRECTIONAL AND WAS STATIC AT A PRESSURE OF 634 PSI (58% SMYS BASED ON NOMINAL PROPERTIES) AT THE TIME OF THE FAILURE. GAS RELEASED FROM THE FAILURE LOCATION DID NOT IGNITE. THERE WERE NO INJURIES, FATALITIES OR DAMAGE TO SURROUNDING STRUCTURES OR THE ENVIRONMENT. INVESTIGATIONS SUBSEQUENT TO THE INCIDENT REVEALED THAT A FAILURE OF THE WAX-TYPE COATING APPLIED DURING ORIGINAL CONSTRUCTION CONTRIBUTED TO THE EVENTUAL FORMATION OF TRANSGRANULAR STRESS CORROSION CRACKING (SCC), ALSO KNOW AS NEAR NEUTRAL PH SCC, IN THE PIPE, WHICH ULTIMATELY RESULTED IN THE PIPELINE FAILURE. THUS, THE DIRECT CAUSE OF THE FAILURE WAS THE NEAR NEUTRAL PH SCC, AS DOCUMENTED BY A THIRD-PARTY METALLURGICAL ANALYSIS. AND THE ROOT CAUSE OF THE SCC ON THE RUPTURED PIPE WAS ATTRIBUTED TO THE COATING THAT FAILED TO PERFORM ITS INTENDED PURPOSE OF ELIMINATING THE ENVIRONMENTAL COMPONENT REQUIRED FOR TRANSGRANULAR SCC TO INITIATE AND PROPAGATE. CONCURRENT TO THE ROOT CAUSE FAILURE INVESTIGATION, WHICH INCLUDED A REVIEW OF THE RESPONSE OF OPERATIONS AND GAS CONTROL PERSONNEL DURING THE EVENT, REPAIRS WERE MADE TO THE 8250 LINE, INCLUDING SUBSEQUENT MULTIPLE PRESSURE TESTS TO ASSURE PIPELINE FACILITY INTEGRITY AND SAFETY.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: MATERIAL FAILURE OF PIPE OR WELD — ENVIRONMENTAL CRACKING-RELATED.

PHMSA indexed costs: $3,907,400 reported total cost, $1,979,193.073 in 1984 dollars, $4,823,077.1 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.