Corleto, "Fundamental slow crack growth properties using instrumented PENT testing," Proceedings of the 17th International Plastic Fuel Gas Pipe Symposium, Oct.
Table 1: SCG Tests on Butt-fusion Joint ("B") Materials of PE4710 Bimodal HDPE 10,000 Hours PENT ("10k") and 2,000 Hours PENT ("2k") Resins SIF, [K.
This is obviously a poor criterion since the notch which causes a certain lifetime is strongly nonlinearly related to thickness and strongly depends on the PENT value.
11 that the effect of temperature is contained in the exponential term and that PF, the ratio of lifetime to PENT, is proportional to the exponential term.
The critical notch depth depends on pipe geometry, pressure, residual stress, PENT value, and temperature.
The current 10% thickness rule used by industry for deciding when to discard a pipe is simplistic because the absolute value of the pipe thickness, the PENT value of the resin, and the temperature are the important factors.
OD (mm) Pipe thickness (mm) PENT (hr) Life time (mm) 60.
The primary control of the life time of the pipe depends on the choice of the resin with respect to its PENT value.
If the PENT value is not known for an old pipe line, remove a piece of pipe and compression mold it in accordance with ASTM F1473 and make a PENT test.
5 years for pipe failure per 1 hr of PENT instead of 13.
The current ASTM specification D2513 requires a min-imum PENT value of 100 hr.
It can be found by measuring the lifetime of the pipe with the specific defect at 80[degrees]C and comparing it with the lifetime of the same resin in the PENT test as was done by Lu and Brown .