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PP vs PVC for pipes and fittings for sewer, drainage applications

PP vs PVC for pipes and fittings for sewer, drainage applications

While PVC sewer fittings are all rated 400KPa (SN 8), both SANS 8773 and SANS 21138 allow lower stiffness ratings for fittings. A lower stiffness rating makes for a thinner wall thickness and, therefore, a cheaper product. Low-stiffness pipes and fittings are intended for use in shallow drains, whereas SN 8 (400kPa) pipes and fittings can be used in all drains and deep sewers.

“The South African market is not well educated to look for, and know, the difference. Hence, SN 2 (100kPa) and SN 4 (200kPa) PP sewer fittings are sometimes installed in main sewer lines — an application they were not designed or intended for. This may lead to premature failure of sewer lines,” DPI Plastics technical and product manager Renier Snyman warns.

“PP is a new entrant with a minimal track record in the sewerage and drainage market compared to PVC, both locally and abroad,” Snyman points out. His call for increased awareness of PP versus PVC comes in light of PP fittings for sewer and drainage applications slowly being introduced into the local market.

DPI Plastics offers a full product range of PVC pipes up to 630mm, and fittings are available for these sizes. However, only 110mm PP sewer fittings are available in South Africa. “This means that a full system and size range of pipes and fittings are not available locally in PP material,” Snyman cautions.

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