TEXAS GAS TRANSMISSION, LLC

Incident Narrative

TEXAS GAS EXPERIENCED A PIPELINE FAILURE OF ITS MAIN LINE SYSTEM 26"" NO. 1 LINE IN UNION PARISH, LOUISIANA. THERE WERE NO INJURIES. THE CAUSE REMAINS UNDER INVESTIGATION. 3-15-16 UPDATE TO FINALIZE REPORT INCLUDING COST AND CAUSE. BASED ON STRESS ENGINEERING'S VISUAL EXAMINATION AND METALLURGICAL ANALYSES OF THE SAMPLES PROVIDED, ALONG WITH OBSERVATIONS FROM A VISIT TO THE SITE, SES CONCLUDED THAT THE MONROE FAILURE WAS CAUSED BY A COMBINATION OF CORROSION AND NEAR-NEUTRAL PH STRESS CORROSION CRACKING. THE INFORMATION AVAILABLE TO SES DID NOT ALLOW A DETERMINATION OF THE PRECISE TIMING OR EXACT CONDITIONS THAT LED TO THE FAILURE. HOWEVER, IT WAS APPARENT THAT CORROSION ENLARGED CRACKS IN THE PIPE, THEREBY SIGNIFICANTLY CONTRIBUTING TO THE FAILURE. THE MECHANICAL PROPERTIES OF THE PIPE MATERIAL WERE TESTED AND FOUND TO MEET THE REQUIREMENTS OF API 5LX IN EFFECT IN 1948 (AS WELL AS CURRENT REQUIREMENTS). WHILE THE MATERIAL TOUGHNESS WAS LOW, THIS PROPERTY ALONE DID NOT PLAY A SIGNIFICANT ROLE IN THE FAILURE. 4-29-16 REVISED CAUSE ON PART G TO REFLECT LABORATORY ANALYSIS FINDINGS. 5-23-16 REVISED PER PHMSA REQUEST TO REPORT CAUSE UNDER SECTION G5 INSTEAD G1.