? Description: At present, the building water supply industry, high-rise building water supply and fire long-term use of pressure pipes is about 1.6MPa, so the design pressure lined steel pipe to determine 2.0MPa can basically meet the requirements of building water pressure , an important parameter while this parameter is the wall thickness design. Temperature is also an important parameter in the design of pipe, plastic-lined steel pipe determines the allowable stress of the material. In the industry, according to the movement of water into the cold water temperature and hot water, cold water temperature is generally 0 ℃ ~ 25 ℃, but the temperature of the medium surface mounted pipeline affected by atmospheric temperature, summer temperatures in southern China up to about 40 ℃, while the north In winter temperatures can fall below -40 ℃, but the water below 0 ℃ will be solidified into ice, so water can not reach the goal. So there are some specification insulation in the industry, so that the temperature of the water pipeline has remained above 0 ℃, in order to maintain the fluid can flow. Hot water is generally used for heating, shower, water temperature is usually below 75 ℃, instantaneous temperature up to about 95 ℃. Between the above research, lined steel pipe into the cold water and hot water type two categories, long-term use to determine the type of cold water temperature is 0 ℃ ~ 55 ℃, hot water pipes long-term use temperature of 0 ℃ ~ 75 ℃, instantly temperature up to 95 ℃. Lishui lined steel pipe outer surface with a three-corrosion measures: the first layer is zinc coating, cathodic protection pipe rust formation. Second layer: epoxy primer, a dense polymer layer on the outer protective film is formed of galvanized, so that air, water, isolation, reduce corrosion of the zinc oxide layer, thereby increasing the useful life of the pipe lined pipe. Third layer: paint, strengthen the protective effect film, improve the appearance of the degree of the product. When buried use, the use of appropriate anti-corrosion measures to improve the life of the system; may also be used in plastic-lined steel pipe as the base, the outer surface and then covered with a layer of plastic pipe, "the double-sided plastic-lined steel bars embedded" ( PE pipe + carbon steel pipe + PP pipe) series products directly buried use.