First floor: Working steel pipe According to the design and customer requirements, the seamless steel pipe (GB8163-87) spiral welded pipe (GB9711-88; SY/T5038-92) and straight seam welded pipe (GB3092-93) are generally selected. After the surface of the steel pipe is treated with advanced shot blasting, the derusting grade of the steel pipe can reach Sa2 grade in GB8923-1988 standard, and the surface roughness can reach R=12.5 micron in GB6060.5-88 standard.
Second layer: Polyurethane insulation A high-pressure foaming machine is used to inject the rigid polyurethane foam raw liquid into the cavity formed between the outer sheaths at one time. This is commonly known as the “tube-in-tube foaming process.” One of its functions is waterproof, the other is thermal insulation, and the third is to support the heat network. When the medium temperature is: -50 °C -120 °C, use rigid polyurethane foam insulation layer.
Third layer: high-density polyethylene protective layer The black (yellow) plastic pipe prefabricated with a certain thickness has the function of protecting the polyurethane insulation from mechanical hard objects. The second is that the outer casing of the corrosion-resistant and waterproof polyethylene is made of high-density polyethylene and has a high Mechanical strength and excellent corrosion resistance can protect the pipe from damage caused by external factors during transport, installation and use. Outer casing should be added with antioxidants, UV stabilizers and carbon black.
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