Accelerated Tests for Lifetime Prediction of PE-HD Pipe Grades

Pipe failure in long-term applications is characterized by creep crack initiation and creep crack growth. Both can be determined by fracture mechanics based tests of the pipe materials. Nowadays, several accelerated tests are available: PENT (Pennsylvania Edge Notch Tensile test), FNCT (Full Notch Creep Tensile test), CRB (Cracked Round Bar test) or SHT (Strain Hardening Test) and NCBT (Notched Cylindrical Bars Test). The PENT, CRB and SHT were applied to one unimodal polyethylene (PE 80), four bimodal polyethylene (three of PE 100 and one of PE 100-RC) and one PE-BF (for blow molding). The contribution is focused mainly on two topics: (i) difference in specimen's preparation and test conditions and (ii) comparison of the experimental results obtained using different accelerated tests.