Structure and characteristics of thermal insulation large-diameter spiral steel pipe

Features of thermal insulation large diameter spiral steel pipe:
Polyurethane foam has good mechanical properties and thermal insulation properties. Usually, it can withstand a temperature of 120 °C. The large-diameter spiral tube can withstand the temperature of 180 °C through modification or combination with other thermal insulation materials. The spiral tube has strong thermal insulation performance, which can ensure the internal temperature of the transported material is not subject to external changes, and it has good cold resistance in winter. The sound insulation performance of the spiral steel pipe is very good, and the sound of the liquid flowing through the pipe during transportation can be avoided. At the same time, the spiral steel pipe can be anti-corrosion and does not absorb water, so the installation position of the pipe is not limited and can be used in various places. The construction of the spiral steel pipe is simple and fast, with high efficiency, and reduces the capital cost investment. Spiral tubes are used for low heat loss and can save energy.

Large-diameter spiral steel pipe. The thermal conductivity of the spiral steel pipe is λ=0.013-0.03kcal/m•h•oC, which is much lower than other commonly used pipeline insulation materials in the past, and the thermal insulation effect is increased by 4 to 9 times. Furthermore, its water absorption rate is very low, about 0.2kg/m2. The reason for the low water absorption is that the closed cell rate of polyurethane foam is as high as about 92%. Low thermal conductivity and low water absorption, coupled with a thermal insulation layer and high-density polyethylene or glass fiber reinforced plastic protective shell with good waterproof performance on the outside, have changed the situation of "wearing a wet cotton jacket" for traditional trench laying heating pipes, and greatly reduced the heating pipes. The overall heat loss, the heat loss of the heat network is 2%, which is less than the international standard requirement of 10%.

Insulation large diameter spiral steel pipe structure:
(1) Core pipe: a working steel pipe for conveying steam. The material properties, outer diameter, dimensional tolerance, and minimum wall thickness of the core tube conform to relevant national or industry standards, and the surface of the core tube is free of rust, grease, moisture, and other contaminants.
(2) Protective cushion layer: the interlayer between the core tube and the thermal insulation layer to prevent damage to the inorganic thermal insulation layer due to the displacement of the core tube. When the core pipe is made of spiral welded steel pipe, and the inorganic thermal insulation layer is a hard material, a protective cushion layer is provided. The protective cushion is generally made of aluminum silicate felt, the density is less than or equal to 192kg/m3, the thermal conductivity at room temperature is less than or equal to 0.056w/(m•k), and the shrinkage rate of the heating wire is less than or equal to 4%.
(3) Organic thermal insulation layer: thermal insulation layer made of organic thermal insulation materials. Using polyurethane rigid foam, the density is 55-65kg/m3, the compressive strength is ≥0.2MPa, the thermal conductivity at room temperature is ≤0.027w/(m•k), and the water absorption rate is ≤3%, and the applicable temperature is ≤140℃.
(4) Inorganic thermal insulation layer: thermal insulation layer made of high temperature resistant inorganic thermal insulation materials. Thermal conductivity at room temperature ≤ 0.055w (m•k) according to different structures, microporous calcium silicate (density ≤ 220kg/m3), magnesium silicate, and rock wool (density ≥ 110kg/m3) can be selected. Temperature, compressive strength, and other indicators can also meet the relevant requirements.
(5) Outer protective tube: The outer protective layer that protects the insulation layer from groundwater erosion, supports the core tube, and can withstand a certain pressure. According to different materials, it is generally divided into steel outer protective pipe, high-density polyethylene plastic outer protective pipe, glass fiber reinforced plastic outer protective pipe, composite outer protective pipe, etc. This product generally uses high-density polyethylene (PE) as the outer protective pipe, but in areas with high water levels or abundant surface water, the steel outer protective pipe must be used. The material properties and tolerance dimensions of the steel outer protective pipe conform to relevant national or industry standards. The outer surface of the steel pipe is shot blasted to remove rust.