Long-Term Plastic Pipe Stiffness Measured by Conventional and Accelerated Procedures

Parallel-plate loading mechanism (ASTM D2412 standard test method) was used for investigating the long-term pipe stiffness values of HDPE, PVC and ABS pipes. The conventional and accelerated test procedures were both used. The nominal inside diameters of the test pipes were 300 and 400mm. S-type long-term deflection curve was observed for the test plastic pipes on a semi-log scale. Long-term pipe deflection is a function of pipe material properties, pipe geometry, and external loading conditions. Load deflection rate approximately increases as increasing the pipe diameter. However, the relationship between load-deflection and different plastic pipe materials is still unclear. Long-term pipe stiffness values decrease as increasing test duration on a semi-log scale. The elevated temperature test procedure can be used as an accelerated method for estimating the long-terra pipe deflection and pipe stiffness value in conjunction with the parallel-plate loading mechanism.