ENERGY WEST MONTANA

Incident Narrative

THE 1"" CTS, SDR 11.5, ALDYL-A PIPE AND 1"" SOCKET FUSION COUPLING WERE DIRECTLY UNDER THE FOOTING AND FOUNDATION OF 4601 WILLOWDALE LANE. THERE APPEARED TO BE EXTERNAL DAMAGE TO THE 1"" COUPLING AND THE 1"" CTS PIPING APPEARS TO HAVE BEEN LOWERED IN PLACE BY THE HOME BUILDER. THE 1"" CTS PIPING WAS A DEAD END SERVICE STUB AND WAS UNKNOWINGLY OPERATING AT 230 PSI DUE TO A PREVIOUS UPRATE OF A 10"" STEEL PIPELINE. THE 1"" CTS, SDR 11.5, ALDYL-A PIPE AND 1"" SOCKET FUSION COUPLING WERE SUBJECT TO A SHOCKWAVE CREATED BY THE HOME EXPLOSION. THE 1"" CTS, SDR 11.5, ALDYL-A PIPE AND 1"" SOCKET FUSION COUPLING IS BEING SENT TO AN INDEPENDENT LAB FOR A FORENSIC INVESTIGATION AND TESTING. 4/12/2019: LAB TESTING RESULTS WERE RECEIVED FROM TWO THIRD PARTY CONSULTANTS. RESULTS INDICATED THAT THE 1"" COUPLING FAILED DUE TO SLOW CRACK GROWTH PROPAGATION AS A RESULT OF MULTIPLE STRESSES BEING APPLIED TO THE FITTING. PER THE REPORTS, THE CRACK GROWTH AND LEAK POINT ON THE COUPLING WAS CONSISTENT WITH A TENSILE LOAD ON THE COUPLING. THE PHENOMENA OF A BRITTLE CRACK WHICH STARTS IN THE LOCATION WHERE THE HEAT FUSION JOINED TUBING TERMINATES ON THE INTERIOR OF A SOCKET FUSION HAS BEEN DOCUMENTED PREVIOUSLY IN INDUSTRY. THE CRACK FORMED BY THE NOTCH GEOMETRY CREATED BY THE INSERTED TUBING AND ITS POINT OF HEAT FUSION JOINING TO THE SOCKET WHICH, WHEN UNDER GAS PRESSURE, CAN CREATE A STRESS RISER. THE NOTCH GEOMETRY MAY HAVE BEEN CONTRIBUTED BY THE SOCKET FUSION TOOLS AVAILABLE AT THE TIME OF INSTALLATION. THE FAILURE IS ALSO CONSISTENT WITH INDUSTRY KNOWLEDGE OF ALDYL-A PIPE AND FITTINGS MANUFACTURED PRIOR TO 1984 AND SUSCEPTIBILITY TO INNER WALL CRACKING. THE COUPLING WAS 10"" UNDER THE FOUNDATION OF THE GARAGE AND APPEARED TO BE LOWERED IN PLACE DURING THE CONSTRUCTION OF THE STRUCTURE. LOWERING WOULD HAVE CAUSED TENSILE STRESS ON THE PIPE AND COUPLING. NO EXTERNAL DAMAGES WERE SEEN ON THE PIPE OR COUPLING FROM CONSTRUCTION OF THE GARAGE STRUCTURE. AGAIN PER THE REPORTS, THE INTERNAL PRESSURE IN THE PIPE MAY HAVE ACCELERATED THE FAILURE IN THE COUPLING BUT COULD NOT BE DETERMINED AS THE SOLE ROOT CAUSE OF THE FAILURE. THE TIME TO FAILURE FROM CRACKING COULD NOT BE ESTIMATED OR DETERMINED IN EITHER REPORT. 11/19/2019 - SUBMITTED AS FINAL REPORT WITHOUT FURTHER CHANGES AT THIS TIME.