1.What materials are there for steel-lined plastic composite pipes?
Steel-lined plastic composite pipes use steel pipes as the base pipe and plastic as the coating or lining material. Different types of steel-lined plastic composite pipes have different plastic materials, the most common of which are:
High-density polyethylene (HDPE): This material is used in the lining of some plastic-lined composite steel pipes. For example, in the manufacture of plastic-lined composite steel pipes, professional high-density polyethylene is used to prepare the lining through an extrusion molding process.
Polypropylene (PP): Steel-lined polypropylene pipes (GSF.PP) use polypropylene as the inner coating material.
Polyvinyl chloride (PVC): Including rigid polyvinyl chloride (PVC-U), chlorinated polyvinyl chloride (PVC-C), etc. Steel-lined polyvinyl chloride pipes (GSF.PVC) are mainly lined with this type of material.
Polyethylene (PE): For example, steel-lined polyethylene pipes (GSF.PE), the medium working temperature is -20~80℃.
Polyolefin (PO): It is the inner coating material of steel-lined polyolefin pipes (GSF.PO).
Polytetrafluoroethylene (F): Applied to steel-lined polytetrafluoroethylene pipe (GSF.F), the applicable medium working temperature range is -100~250℃.
Random copolymer polypropylene (PP-R): PSP steel-plastic composite pipe is a composite of steel pipe and random copolymer polypropylene pipe
2.Advantages in materials and structures
The plastic material used in the lining has excellent corrosion resistance and wear resistance, which can greatly extend the service life of the pipeline. For example, the composite pipe using high-density polyethylene (HDPE) as the lining can effectively resist the erosion of external corrosive media1.
The liner and the steel pipe are physically or chemically bonded to form a unique structure. The liner and the outer shell form a protective layer, which not only blocks the erosion of the steel pipe by external corrosive media, but also maintains the strength and rigidity of the steel pipe.
3.Performance
Lightweight and high strength: Compared with traditional metal pipes, plastic-lined composite steel pipes are lighter, but have higher compressive and bending strength, and can withstand greater pressure and load1.
Wide temperature range: Steel-lined plastic composite pipes of different materials can adapt to different temperature ranges. For example, steel-lined polytetrafluoroethylene pipes (GSF.F4) can be used at medium working temperatures of -100~250℃4.
Safe use: The lining material is low-toxic, odorless, and pollution-free, which can ensure that the medium transported by the pipeline is not polluted by secondary pollution and meets environmental protection requirements. For example, the steel-plastic composite pipe that can be directly used in direct drinking water projects has good corrosion resistance in the inner and outer plastic materials12.
Smooth inner wall: not easy to scale and breed microorganisms, reducing the risk of pipeline blockage and water pollution.
Small linear expansion coefficient: For example, Baoyi PSP steel-plastic composite pipes have a small linear expansion coefficient, a long compensation distance, and no deformation when exposed.
4.Construction and connection
Diverse connection methods: During construction, various connection methods such as welding, groove, flange and wire connection can be selected according to different uses, and some connection methods are easy to operate. PSP steel-plastic composite pipes use fully automatic electromagnetic fusion welding, and the pipe and pipe fitting connection machine is fully automatic with one-button "fool-proof" operation. The quality of joint welding is guaranteed, safe and reliable, and watertight
5.Disadvantages
During the gasket replacement construction, if the construction team relies on brute force to remove the pipeline in order to shorten the construction period, it is easy to cause damage to the sealing surface and lining plastic layer of the pipeline. This is because the construction workload is large, the construction period is short, and the pipeline is uneven from the ground, which increases the difficulty of gasket replacement.
