The polyethylene made of polyethylene tube is odorless, non-toxic, waxy, has excellent low temperature resistance (minimum use temperature can reach -70 ~ -100 °C), has good chemical stability, and is resistant to most acid and alkali corrosion ( Not resistant to acids with oxidizing properties), insoluble in common solvents at normal temperature, low water absorption, but due to the linearity of PPR tubes, it can be slowly dissolved in some organic solvents, and does not swell, and has excellent electrical insulation properties; It is very sensitive to environmental stress (chemical and mechanical action) and has poor heat aging resistance. The nature of polyethylene varies from species to species and depends primarily on molecular structure and density. (1) LDPE: low density polyethylene, high pressure polyethylene (2) LLDPE: linear low density polyethylene (3) MDPE: medium density polyethylene, bimodal resin (4) HDPE: high density polyethylene, low pressure polyethylene ( 5) UHMWPE: ultra high molecular weight polyethylene (6) modified polyethylene: CPE, crosslinked polyethylene (PEX) (7) ethylene copolymer: ethylene-propylene copolymer (plastic), EVA, ethylene-butene copolymer , copolymers of ethylene-other olefins (such as octene POE, cyclic olefin), ethylene-unsaturated ester copolymers (EAA, EMAA, EEA, EMA, EMMA, EMAH) with molecular weights of 3,000,000-6,000, The linear polyethylene of 000 is called ultra high molecular weight polyethylene (UHMWPE). Ultra high molecular weight polyethylene is very strong and can be used as a body armor. Plastic pipe characteristics and applications Polypropylene pipe (PPR) (1) PPR pipe (piece) for heating and water supply. The utility model has the advantages of convenient and quick installation, economical and environmental protection, light weight, hygienic non-toxicity, good heat resistance, corrosion resistance, good heat preservation performance and long service life. The pipe diameter is one size larger than the nominal diameter. If PPR32 is equivalent to DN25, PPR63 is equivalent to DN50. The pipe diameter is specifically divided into DN20, DN25, DN32, DN40, DN50, DN63, DN75, DN90, DN110. Pipe fittings are available in a wide variety of tees, elbows, pipe ferrules, reducers, pipe plugs, pipe clamps, brackets, and hangers. The hot water pipe is divided into two parts, the cold water pipe is a green strip pipe, and the hot water pipe is a red strip pipe. The valve has PPR ball valve, globe valve, butterfly valve, gate valve, and copper core inside the PPR material. (2) PPR pipe connection methods include welding, hot melt and screw connection. Among them, the hot-melt connection is the most reliable, the operation is convenient, the airtightness is good, and the interface strength is high. The pipe connection uses a hand-held fusion splicer for hot melt connection. Remove dust and foreign matter from pipes and accessories before connecting. When the red light of the machine lights up and stabilizes, align the pipe to be connected (piece) DN<50 hot melt depth is 1-2MM, DN<110 hot melt depth is 2-4MM. When connected, the tube end is inserted into the heating jacket without rotation to a predetermined depth. At the same time, the tube is pushed onto the heating head without rotation to heat, and after the heating time is reached, the tube and the tube are immediately removed from the heating sleeve and the heating head, and the tube is quickly and non-rotatingly and evenly inserted into the required depth, so that A uniform flange is formed at the joint. The newly welded joint can be calibrated within the specified heating time, but rotation is strictly prohibited. When the pipe and the pipe are heated, excessive heating should be prevented to make the thickness thin. The pipe is deformed within the pipe fitting. Rotation is strictly prohibited during hot melt cannula and calibration. There shall be no open flames at the operation site, and it is strictly forbidden to bend the pipes with open flames. When the heated pipe and pipe are vertically aligned, the force should be light to prevent the elbow from bending. After the connection is completed, the pipe and the pipe must be tightly held for a sufficient cooling time, and after cooling to a certain extent, the hand can be released. When the PP-R pipe is connected with the metal pipe fitting, the PP-R pipe with the metal insert should be used as the transition. The pipe fitting and the PP-R pipe are connected by the hot melt socket, and are connected with the metal fittings or the hardware fittings of the sanitary ware. When using a threaded connection, a polypropylene raw tape should be used as the sealing filler. If the faucet is connected to the mop pool, the inner elbow (threaded inside) is installed at the end of the upper PPR tube. During the installation of the PPR pipe, do not use excessive force to avoid damage to the threaded fittings and cause leakage at the joint. Pipe cutting can also be cut by special pipe: the pipe cutter blade should be adjusted to match the diameter of the pipe to be cut. When the rotation is cut, the force should be evenly applied. After cutting, the complete round of the complete rounder should be applied to the fracture. When the pipe is broken, the section should be perpendicular to the pipe axis and free of burrs.