Polyvinyl chloride water supply pipe
DATE：2022/8/27 9:13:18 / READ： / SOURCE：This station
Polyvinyl chloride water supply pipe
PVC water supply pipe is extruded with special sanitary PVC resin and has the following characteristics. ① Non toxic, chemical resistant, not affected by chlorine or bleaching powder in water. ② It has strong water carrying capacity, small friction coefficient and small flow resistance to water.③ Compared with other plastic pipes, it has better aging resistance and weather resistance, and is free of scale and rust when used in water temperature below 50 ℃ for a long time. ④ It is non flammable and can be extinguished from the fire source. ⑤ The pipes are easy to install and cheap. (1) PVC resin for drinking water pipe molding shall be selected as raw material. It shall be suspension pvcsg5 resin (k value is 68-70, average polymerization degree is 1000). The content of vinyl chloride monomer in the resin shall be less than or equal to 3mg / kg. The maximum allowable value of lead, cadmium and mercury in auxiliary material stabilizer and lubricant is 0.005mg/l. (2) Molding process: ① production process sequence of extrusion molding of PVC conveying drinking water pipe: A. production process sequence of molding pipe with single screw extruder: PVC resin screening → metering of various raw materials in the formula → high-speed hot mixing of raw materials → cooling and mixing of raw materials → extrusion granulation → extrusion and melting of raw materials → mold molding of pipe blank → cooling and setting → traction → cutting → quality inspection → weighing and warehousing; B The production process sequence of forming pipes with twin-screw extruder (counter rotating meshing type) is: PVC resin screening → metering of various raw materials in the formula → high-speed hot mixing raw materials → cooling and mixing raw materials → extrusion and melting with twin-screw extruder → mold forming pipe blank → cooling and setting → traction → cutting → quality inspection → weighing and warehousing ② refer to Chapter 4 for the production process conditions of raw material mixing and extrusion granulation. ③ Process temperature a The process temperature of single screw extrusion molding pipe is 100 ~ 140 ℃ in barrel feeding section, 150 ~ 170 ℃ in plasticizing section and 160 ~ 180 ℃ in homogenizing section. The molding die temperature is 170 ~ 190 ℃. b. The process temperature of the twin-screw extrusion molding pipe is 130 ~ 160 ℃ in the feeding section, 150 ~ 155 ℃ in the plasticizing section and 160 ~ 170 ℃ in the homogenizing section. Molding die 170 ~ 180 ℃. The process temperature of conical twin-screw extrusion forming pipe is 180 ~ 195 ℃ in the feeding section, 170 ~ 180 ℃ in the plasticizing section and 170 ~ 175 ℃ in the homogenizing section. The molding die temperature is 170 ~ 190 ℃. (3) Quality requirements the quality requirements of rigid PVC water supply pipes shall comply with the provisions of GB / t10002.1-1996. In table 5-42, the size of the dead rigid PVC water supply pipe refers to the nominal size of the outer diameter of the rigid PVC pipe under different pressure conditions when the transmission water temperature is 20 ℃. See table 5-43 for the correction coefficient of the drop value of the pressure bearing capacity of the rigid PVC pipe at different temperatures. 5.4.3 PVC drainage pipe PVC drainage (sewage) pipe can replace the traditional cast iron drainage pipe and is widely used in the drainage (sewage) pipeline of urban buildings. Because of its light weight, corrosion resistance, not easy to scale, not easy to block, and no health index requirements, it is widely welcomed by the construction industry. (1) Raw material selection: the main material for extrusion molding of rigid PVC pipes for drainage is suspension PVC SG5 resin (average polymerization degree 1000), and a small amount of stabilizer, lubricant, filler and other additives are added to form the material formula. (2) Molding process: the production process sequence, equipment selection and plasticizing process temperature of PVC drainage pipe extrusion molding are completely the same as that of ordinary PVC pipe, and can refer to the PVC pipe molding process. (3) Quality requirements: the quality of PVC drainage pipe shall comply with the provisions of GB / t5836.1-92. See table 5-47 for its mechanical property requirements. See table 5-48 for outer diameter, wall thickness and deviation requirements of PVC drainage pipe. (4) Key points of process operation for extrusion molding of PVC drainage pipes, in addition to referring to the key points of extrusion molding process of ordinary rigid PVC pipes, the following points shall also be noted. ① Application of PVC drainage pipe. If there are no special requirements, in order to reduce the production cost of pipes, more calcium carbonate filler can be added to the raw materials, but attention should be paid to the fineness control of calcium carbonate (the fineness of light calcium carbonate should not be less than 320 mesh, and the fineness of heavy calcium carbonate should not be less than 500 mesh), and the whiteness should be greater than 90%. Calcium carbonate is preferably activated. ② The proportion of filler in the formula increases. In order to reduce the extrusion difficulty of raw materials, some plasticizers can be appropriately added to the raw materials. ③ An increase in the amount of filler in the raw material. The fluidity of the melt becomes poor. Note that the compression ratio of the mold for forming this melt is about 5; The diversion cone angle is selected between 60 ° and 90 °; The straight section of the core rod for forming the tube blank should be longer, and the length is about 2 times of the tube diameter; The length of the vacuum sizing sleeve is about 400mm. ④ When PVC pipes are extruded by twin-screw extruder, the plasticizing time of materials in the barrel is shorter than that of single screw extrusion, and the plasticizing quality is better, so the amount of stabilizer added in the material formula can be less than that of single screw extrusion pipes. (5) Extrusion molding of buried PVC drainage pipes: the rigid PVC drainage pipes buried underground for urban discharge of domestic and industrial wastewater are different from the drainage pipes in buildings in that the diameter of the pipes is relatively large. According to the national standard, the minimum diameter of buried underground drainage pipe is + 110mm. ① Raw materials and equipment for forming buried drainage pipes the raw materials and production equipment for forming buried PVC drainage pipes are basically the same as those for forming PVC water supply pipes, which can be produced by referring to the parameters in 5.4.2. However, due to the large diameter of the pipe, the twin-screw extruder is generally used for extrusion. A flaring machine is required in the production process to flaring the end of the plastic pipe.The main raw materials for forming buried drainage pipes are suspension PVC resin SG5, and the auxiliary materials include stabilizers, lubricants and other types. The reference examples of its composition formula (dark gray) are as follows (parts by mass). Polyvinyl chloride (pvcsg5s1000) composite stabilizer) 2.8 stabilizer ogp-101 (lead stearate (PBST) 0.5 imported from Japan) the quality of buried polyvinyl chloride drainage pipes the difference between the quality of buried polyvinyl chloride drainage pipes and the quality requirements of drainage pipes in buildings is the requirement of ring stiffness.Author：admin