Ring Stiffness by Long-Term Creep and Relaxation Tests of Rib-Reinforced uPVC Sewer Pipes

The ring stiffness of a new design ribreinforced uPVC sewer pipe is studied. Creep measurement for 1000 h gives a reasonable first approximate of long-term stiffness. Because of the specific creep behaviour of uPVC, the measurement for 10,000 h gives a higher estimated stiffness. Relaxation results on new pipes compare with those on conventional smooth wall uPVC sewer pipes. Creep and stress relaxation in plastics are material properties.

Sewer pipes are developing towards lighter constructions. New product standards and test methods are needed. Practical and good experience of plastics sewer pipes of comparable materials is available since early 1960s. Some early results of laboratory tests help to build a bridge between the stiffness behaviour of traditional smooth solid wall pipes and new rib-reinforced constructions. New test data of new products is still necessary to confirm the quality.