Natural weathering effects on some properties of CPVC pipe material

Polyvinyl chloride (PVC) and more recently chlorinated-PVC (CPVC) pipes are extensively used for water distribution, wastewater and in limited applications for gas distribution. More and more cities are using CPVC pipes and pipefittings in their water distribution networks. Chlorinated-PVC is a material designed to withstand higher service pressures and temperatures than PVC. Its utilization in harsh environmental conditions, such as those of the Arabian Peninsula requires understanding of weathering effects, including UV, moisture and high ambient temperature on its mechanical properties. In this work, tensile and single-edge-notch bending (SENB) specimens prepared from locally manufactured CPVC commercial pipes have been naturally weathered for different periods (1-9 months) in harsh Saudi weather conditions. Standard tensile and SEN fracture toughness tests were performed after natural exposure periods of 1, 2, 3, 6 and 9 months. The tensile test results show that exposure for periods up to 9 months, including summer season, had limited effects on the tensile strength and modulus of elasticity of the material. This was expected given that the damage due weathering is mainly a surface phenomenon. However, the deterioration of the ultimate elongation is noticeable for exposure periods as low as 1 month. Analysis of fracture toughness results reveals a general trend that indicates a deterioration of this property at the beginning of the exposure time.