Abstract
Mandatory Appendix XXVI of Section III of the ASME B&PV Code contains rules for the construction of Class 3 pressure piping systems comprised of PE4710 High Density Polyethylene (HDPE) with a minimum Pennsylvania Notched Test (PENT) rating of 2,000 hours. Appendix XXVI contains acceptance standards for the maximum allowable depths of gouges, cuts or other surface conditions that are characterized as indentations. The acceptance standards are very conservative, in particular for large diameter HDPE pipes. Less restrictive maximum allowable indentation depths for PE4710 HDPE pipes with a minimum PENT rating of 2,000 hours were previously developed based on analyses of tests on HDPE pipes containing scratches. These less restrictive maximum allowable indentation depths were published in the ASME Section III Code Case N-891 as an alternative to the acceptance standards in Appendix XXVI. The PENT rating of PE4710 HDPE material can significantly exceed 2,000 hours, and the current maximum allowable indentation depths in Code Case N-891 are overly-restrictive for the higher PENT ratings. Maximum allowable indentation depths for PENT ratings up to 10,000 hours have been developed, and are proposed to be implemented into a revision of Code Case N-891 and Appendix XXVI. The technical basis for the maximum allowable indentation depths for these higher PENT ratings is provided in this paper. The proposed revisions to Code Case N-891 include a provision to permit use of results from accelerated PENT testing at a higher temperature and stress level than standard PENT test conditions. The technical basis for the use of results from accelerated PENT testing is also provided in this paper.