Layer 1: Working Steel Tube Layer
Seamless pipe (GB8163-87), spiral welded pipe (GB9711-88; SY/T5038-92) and straight welded pipe (GB3092-93) are usually selected according to design and customer's request.
After the surface of steel tube is treated by advanced shot peening rust removal technology, the grade of steel tube rust removal can reach Sa2 level in GB8923-1988 specification, and the surface roughness can reach R=12.5 micron in GB6060.5-88 specification.
Layer 2: Polyurethane Thermal Insulation Layer
A rigid polyurethane foam plastics raw liquid is injected into the cavity formed between the steel pipe and the outer protective layer by a high-pressure foaming machine at one time. That is commonly known as "tube-in-tube foaming process". Its function is waterproof, heat preservation and self-weight support of heat network. The rigid polyurethane foam is chosen as insulation layer when the temperature of delivery medium is -50 ~120 ~C.
Layer 3: High Density Polyethylene Maintenance Layer
Prefabricated black (yellow) plastic pipes with a certain wall thickness. Its function is to protect the polyurethane insulation layer from mechanical damage. The second is the characteristics of anti-corrosion, waterproof and reinforced polyurethane insulation pipes: using steel pipes as external maintenance layer, it has high strength. It is not easy to damage and can accept large upper load. In order to achieve short life, the steel casing should be stopped anti-corrosion treatment. The design of rolling support structure is reasonable, the rolling friction is small, the force of fixed support is reduced, the mechanical analysis principle is simple, and the stability and safety of pipeline have been greatly improved. The vacuum layer completely eliminated the heat conduction and convection in the air layer and greatly reduced the heat loss. Compared with the air layer structure, the outer wall temperature can be reduced by 8-13 C under the same thermal insulation thickness. Vacuum extraction installation has thoroughly solved the problem that the inner wall of the outer steel casing is easily corroded by hot and humid air, and greatly improved the operation life of the directly buried steam pipeline. The product life has been improved to 30 years.
This article is supported by polyurethane insulating steel pipe manufacturer. For more details, please click on our official website at https://www.sdhpgy.com. We will provide you with satisfactory service wholeheartedly.
