There is a need for ASME B&PV Code procedures and acceptance criteria for evaluation of flaws detected by inspection of high density polyethylene (HDPE) piping items in safety Class 3 systems. To support the development of flaw acceptance criteria for butt fusion joints in the HDPE pipe, modified PENT tests were performed on specimens cut from fused HDPE pipes with surface or subsurface flaws placed in the joints prior to fusing. A series of PENT tests have been completed with a range of flaw sizes, temperatures and applied stresses. The failure time from the tests has been correlated to the net section stress and the stress intensity factor for both surface and subsurface flaws. In particular, statistical analysis was performed to fit the test results to the Brown and Lu’s Equation that models the failure time as a function of stress intensity factor and temperature.  The fitted Brown and Lu’s Equation has been used to estimate the allowable stress intensity factors for a piping lifetime of 50 years (438,000 hours) at the maximum code allowable temperature.  The allowable flaw size in butt fusion joints at the maximum code allowable stress has also been calculated using the relation between the flaw size and the stress intensity factor for each type of flaws.  


Analysis of Hdpe Failure Data in Support of Development of Flaw Acceptance Criteria for Butt Fusion Joints

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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