HIGH POINT GAS TRANSMISSION, LLC

Incident Narrative

DUE TO CHARACTER LIMITS, SEE ORIGINAL REPORT 20220107 FOR INCIDENT DESCRIPTION. *UPDATE 10/31/22* THE LAB COMPANY (STRESS ENGINEERING) THAT THE SAMPLES WERE SENT TO IS CURRENTLY PREFORMING METALLURGICAL ANALYSIS ON BOTH SAMPLES THAT THIRD COAST SENT. THE CHIEF INCIDENT INVESTIGATOR THAT THIRD COAST CONTRACTED TO INVESTIGATE THE LAKE LERY INCIDENT IS STILL CONDUCTING THE INVESTIGATION AND INTERVIEWING WITNESSES. MEETINGS WITH THIRD COAST, THE INVESTIGATOR AND THE US COAST GUARD HAS PRODUCED A MARINE CASUALTY INVESTIGATION BY THE COAST GUARD. REPAIRS TO THE 20' ARE UNDER WAY AND ARE NEAR COMPLETION INCLUDING BACKFILLING THE HOLE THAT WAS CREATED. TO PREVENT THIS FROM OCCURRING IN THE FUTURE THE PIPELINE WILL BURIED, HOLE BACK FILLED AND 2 LEVELS OF ARTICULATING CONCRETE MATES WILL BE PLACED ON TOP ALONG THIS SECTION OF PIPE. *UPDATE 01/05/23* THE 20' GATE 6 TO TOCA LINE HAS BEEN DEWATERED, CUT, AIR GAPPED, AND CAPPED FROM ANY PRESSURE SOURCE AND PLACED UNDER A NITROGEN BLANKET. *UPDATE 02/7/23* STRESS ENGINEERING (SES) PERFORMED SEVERAL EXAMINATIONS OF THE PIPE SAMPLES SENT FOR ANALYSIS INCLUDING LASER SCANNING, VISUAL EXAMINATION, SCANNING ELECTRON MICROSCOPY (SEM), ENERGY DISPERSIVE X-RAY SPECTROSCOPY (EDS), X-RAY DIFFRACTION (XRD), CHEMICAL ANALYSIS, MECHANICAL TESTING AND METALLOGRAPHIC EXAMINATION. THE TWO TRANSVERSE FRACTURES ON THE TWO PIPE SEGMENTS (NORTH AND SOUTH) ORIGINATED AT THE 6 O'CLOCK POSITION. THE TWO HELICAL, CIRCUMFERENTIAL FRACTURES LIKELY OCCURRED FOLLOWING A LONGITUDINAL RUPTURE ALONG THE BOTTOM OF THE 13-FEET LENGTH PIPE SEGMENT(S) THAT WAS/WERE DISPLACED AND NEVER RECOVERED. PITTING CORROSION WAS FOUND ON THE INSIDE SURFACE OF THE TWO PIPE SEGMENTS ANALYZED BY SES. THE PITS WERE FOUND TO BE AS DEEP AS 50% OF THE WALL THICKNESS IN THE NORTH SECTION. THE INSIDE SURFACE SCALE CONTAINED IRON CARBONATE AND IRON SULFIDE, WHILE THE DEPOSITS FROM THE PITS CONTAINED IRON CARBONATE AND IRON OXIDE ' WHICH ARE TYPICAL OILFIELD CORROSION PRODUCTS FROM ACID GASES. THE TENSILE PROPERTIES MET THE REQUIREMENTS FOR GRADE X52 STEEL PER API 5LX (1953) SPECIFICATIONS. THE MICROSTRUCTURE OF THE PIPE BASE MATERIAL WAS TYPICAL OF GRADE X52 CARBON STEEL. WITHOUT THE MISSING PIPE SEGMENT(S) AND THE ABILITY TO EXAMINE IT/THEM, SES CANNOT CONCLUSIVELY DETERMINE THE CAUSE OF THE RUPTURE, NOR CAN IT RULE OUT CERTAIN POSSIBLE CAUSES. MULTIPLE ATTEMPTS WERE CONDUCTED USING A COMBINATION OF DIVERS AND HYDROGRAPHIC/MAGNETOMETER UP TO 1 MILE FROM RELEASE POINT; LOCATING/MARKING AND INVESTIGATING BY DIVER HEAVY METAL DEBRIS TARGETS. THE 13-FOOT PIECE WAS NEVER FOUND AND RECOVERED.