Abstract: PVC-U water supply pipe fittings are mainly made of sanitary grade polyvinyl chloride (PVC) resin, with appropriate stabilizers, lubricants, fillers, color enhancers, etc. added. They are extruded by plastic extruders and injection molded by injection molding machines. Through cooling, curing, shaping, inspection, packaging and other processes, the production of pipes and fittings is completed. Compared with traditional pipes, PVC-U pipes have the advantages of light weight, corrosion resistance, low water flow resistance, energy saving, quick installation, and low cost