TENNESSEE GAS PIPELINE COMPANY — Gas transmission and gathering — incident on 2015-03-02

Gas transmission and gathering incident in Not Within a Municipality, MARSHALL County, MS. Reported cause: MATERIAL FAILURE OF PIPE OR WELD. Reported consequences: 0 fatalities, 0 injuries, 3664.1 NATURAL GAS released, $238,760 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: 20150040.

Operator ID: 19160.

Reported incident date: 3/2/2015 6:48.

Location detail: 66-1+2.73

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

Cause detail: A PIPELINE LEAK OF NATURAL GAS RESULTING IN NO INJURIES, FIRES, OR CUSTOMER IMPACTS WAS DISCOVERED ON MARCH 2, 2015 ON SECTION OF THE 100-1 MAINLINE OF TGP IN MARSHALL COUNTY, MISSISSIPPI. THE SEGMENT FROM VALVE SECTION 66-1 TO 67-1 WAS SECURED AND PROMPTLY BLOWN DOWN TO ISOLATE THE LEAK AND INITIATE REPAIRS. THE IMPACTED SEGMENT OF PIPE WAS SENT OFF FOR METALLURGICAL ANALYSIS ON MARCH 6, 2015 AND THE RESULTS SHOW THAT THE FRACTURE INITIATED FROM MULTIPLE ORIGINS ON THE INSIDE SURFACE OF THE PIPE AT THE PEAK OF THE WRINKLE. THE FRACTURE MODE WAS BRITTLE (QUASI-CLEAVAGE). THE FRACTURE SHOWED NO EVIDENCE OF FATIGUE AND THE FRACTURE LOCATION WAS ON THE TOP OF A RIDGE CONTAINING TWO 1� SAG WRINKLE BENDS. CONSTRUCTION RECORDS INDICATE THE WRINKLE BENDS WERE COLD-FORMED AND COLD WORK COULD REDUCE DUCTILITY. THE COLD-FORMED REGION IS ALSO POTENTIALLY SUSCEPTIBLE TO STRAIN-AGING, WHICH COULD ALSO CONTRIBUTE TO LOWER DUCTILITY. THESE FACTORS COULD INCREASE THE DUCTILE TO BRITTLE TRANSITION TEMPERATURE OF THE WRINKLE BEND COMPARED TO THE PIPE BODY. RESULTS OF THE ROOT-CAUSE ANALYSIS SHOW THAT THE PRIMARY METALLURGICAL FAILURE MECHANISM WAS BRITTLE FRACTURE AND THAT THE CRACK APPEARS TO HAVE FAILED BY TENSILE OVERLOAD. TGP WAS UNABLE TO DETERMINE THE SOURCE OF EACH OF THE TENSILE FORCES, BUT THE TENSILE OVERLOAD DOES NOT APPEAR TO BE A RESULT OF THIRD PARTY DAMAGE OR OBSERVABLE LAND MOVEMENT. IN ADDITION THE FOLLOWING CONCLUSIONS ARE PRESENTED: 1. THERE WAS NO EVIDENCE THE FAILURE RESULTED FROM INSERVICE FATIGUE CRACK GROWTH OR STRESS CORROSION CRACKING. 2. THE MAOP WAS NOT EXCEEDED AND OVERPRESSURE WAS NOT A CONTRIBUTING FACTOR TO THE FAILURE. 3. INTERNAL OR EXTERNAL CORROSION WAS NOT A CONTRIBUTING FACTOR.

PHMSA trend classification: significant incident, not serious.

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

PHMSA indexed costs: $281,890 reported total cost, $158,492.713 in 1984 dollars, $344,370.543 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.