GB/T 8923中Sa2.5的规定，外壳管内表面张力达到50达因/厘米 9、聚乙烯外护管采用高密度聚乙烯材料，辅以抗氧剂等各种助剂制成，并对原材料和产品质量进行严格检验，确保产品质量达到CJ/114标准和直埋管外护管的技术要求，提高了外护管的整体质量。
方管由于聚氨酯硬质泡沫保温层紧密地粘结在钢管外皮， 保温无缝钢管制作流程隔绝了空气和水的渗入，能起到良好的防腐作用。同时它的发泡孔都是闭合的，吸水性很小。方管高密度聚乙烯外壳、方管玻璃钢外壳均具有良好的防腐、绝缘和机械性能。因此，工作钢管外皮很难受到外界空气和水的侵蚀。只要管道内部水质处理好，据国外资料介绍，方管的使用寿命可达50年以上， 保温无缝钢管比传统的地沟敷设、架空敷设使用寿命高3~4倍。
Square pipe performance characteristics: 1, the use of low thermal conductivity insulation seamless steel pipe insulation performance good rigid polyurethane as insulation material, with excellent insulation. 2. When water at 130℃ is transported to a distance of 40 kilometers after normal operation, the temperature drop is only about 1℃. 3, has a strong waterproof and corrosion resistance, no need to be attached to the ditch, can be directly buried in the ground or water, simple and rapid construction, low overall cost.
4. It also has good corrosion resistance and impact resistance under low temperature. The production process of seamless steel pipe with insulation can be directly buried into the frozen soil.
5. The prefabricated insulation pipe USES corrosion-resistant (HDPE: high-density polyethylene) outer sleeve, which is free from biological and chemical corrosion. 6. Various pipe diameters and insulation thicknesses between DN20 and DN1200 can be provided according to customers' needs, as well as matching fittings (elbow, tee, variable diameter pipe, fixed section, etc.).
Sa2.5 in GB/T 8923 the provisions of the casing pipe surface tension reached 50 dyne/cm 9 with high density polyethylene, polyethylene outer protection pipe material, supplemented by antioxidant and other additives, and carries on the strict inspection for raw materials and product quality, to ensure product quality reach the standard CJ / 114 and buried pipe outer security technology requirements, improve the overall quality of external protecting tube.
As the rigid polyurethane foam insulation layer of the square pipe is closely bonded to the steel tube skin, the production process of the insulated seamless steel pipe can isolate the infiltration of air and water, which can play a good role in anti-corrosion. At the same time, its foam holes are closed, water absorption is very small. The high density polyethylene shell of the square pipe and the glass reinforced plastic shell of the square pipe have good anti-corrosion, insulation and mechanical properties. Therefore, the outer skin of the steel tube is difficult to be eroded by the outside air and water. As long as the water inside the pipe is treated well, according to foreign information, the service life of the square pipe can reach 50 years or more, and the service life of the insulated seamless steel pipe is 3~4 times higher than that of the traditional trench laying and overhead laying.
Prefabricated directly buried thermal insulation pipe made of polyurethane has good mechanical properties and adiabatic properties. Under normal conditions, it can withstand high temperature 120℃ and can withstand high temperature 180℃ through modification or combination with other thermal insulation materials. It is suitable for thermal insulation engineering of various cold and hot water pipelines with high and low temperature. Advantages: 1, reduce the cost of the project. Calculate according to concerned branch, double control heat supply conduit, can reduce the 25% of project cost below general circumstance (use glass fiber reinforced plastic to do protective layer) and 10%(use high-density polyethylene to do protective layer) left and right sides.