Process and connection of large-diameter plastic-coated steel pipes: Large-diameter plastic-coated steel pipes are mainly divided into two types: inner plastic-coated steel pipes and inner and outer plastic-coated steel pipes. The coating material is generally epoxy resin and polyethylene, and can also be customized according to customer requirements. Plastic-coated steel pipes solve the defects of previous steel-plastic pipes in production and installation and have been well-received and recognized by many customers.

Process standards for large-diameter plastic-coated steel pipes:
1) Coating adhesion: The adhesion of the polyethylene coating layer is ≥30N/cm, and the adhesion of the epoxy resin coating is 1 to 3 levels.
2) Bending performance: Steel-plastic pipes with a nominal diameter of no more than 50mm are bent, no cracks will occur after bending, and no stratification will occur between the steel and the inner and outer plastic layers.
3) Flattening performance: Steel-plastic pipes with a nominal diameter greater than 50mm and not exceeding 600mm are flattened, no cracks will occur after flattening, and no stratification will occur between the steel and the inner and outer plastic layers.
4) Hygiene requirements: The inner plastic layer of the steel-plastic pipe for transporting drinking water, hot and cold water should meet the requirements of GB/T 17219.
5) Pinhole test of the coated plastic layer: Use an electric spark detector to check the entire inner and outer surfaces of the steel-plastic pipe provided for the test. No electric sparks should be generated during the test.
6) Fire resistance test: The steel-plastic pipe for fire protection should be able to withstand the fire resistance test for 15 minutes, and there should be no leakage and deformation damage after the test.

Application field of large-diameter plastic-coated steel pipe: The base steel pipe of the large-diameter plastic-coated steel pipe is made of ordinary hot-dip galvanized welded steel pipe (or welded pipe, spiral pipe, seamless steel pipe) after surface treatment and heating, and then sprayed (rolled, sucked, dipped) with various plastic powders. Large-diameter plastic-coated steel pipes are mainly used in water supply and drainage, fire sprinklers, industrial circulating water, internal and external corrosion protection, deionized pure water, electric and optical cable protective sleeves, and other fields. The industries involved include civil, construction, industry, chemical, electricity, petroleum, medicine, ocean, highway, subway tunnel, natural gas, shipbuilding, agriculture, coal mining, and other industries. The company’s product performance, technical indicators, and appearance have reached the domestic excellent level and can provide systematic supporting services according to customer needs. Large diameter plastic coated steel pipes refer to the implementation standards: CJ/T120-2008 “Plastic coated steel pipes for water supply” GB/T17219-1998 “Sanitary performance index implementation standards” Automatic sprinkler fire extinguishing system Part 20 Coated steel pipes (GB/T5135.20—2010)

Technical parameters of large diameter plastic coated steel pipes:
(1) Coating material: modified heavy anti-corrosion epoxy resin
(2) Common color: red
(3) Coating thickness: 250um-550um
(4) Coating method: internal and external spraying
(5) Product specifications: DN15-DN1200
(6) Ambient temperature: -30℃ to 80℃ (peak 760℃)
(7) Conventional pressure: 0.1Mpa-2.5Mpa
(8) Connection method: thread, groove, flange connection, etc.