吉林电网聚氨酯保温钢管
预制聚氨酯保温钢管从里到外分三层结构：
第一层：工作钢管层
根据设计和客户的要求一般选用无缝钢管、螺旋钢管和直缝钢管。钢管表面经过先进的抛丸除锈工艺处理后，钢管除锈等级可达gb/t8923-1988标准中的sa2级，表面粗糙度可达gb6060.5-88标准中r=12.5微米。
第二层：聚氨酯保温层：
用高压发泡机在钢管与外护层之间形成的空腔中一次性注入硬质聚氨酯泡沫塑料原液而成，即俗称的“管中管发泡”。
第三层：高密度聚乙烯保护层：
预制成一定壁厚的黑色或黄色聚乙烯塑料管材。聚乙烯无臭，无毒，手感似蜡，具有优良的耐低温性能，最低使用温度可达-70～-100℃，化学稳定性好，能耐大多数酸碱的侵蚀(不耐具有氧化性质的酸)，常温下不溶于一般溶剂，吸水性小，但由于其为线性分子可缓慢溶于某些有机溶剂，且不发生溶胀，电绝缘性能优良。其作用一是保护聚氨酯保温层免遭机械硬物破坏，二是防腐、防水。高密度聚乙烯聚氨酯发泡保温钢管执行：sy/t114-2000和sy/t115-2001标准。
prefabricated polyurethane insulation steel pipe is pided into three layers from inside to outside: the first layer: working steel pipe layer seamless steel pipe, spiral steel pipe and straight seam steel pipe are generally selected according to the design and customer's requirements. after the steel pipe surface is treated by advanced shot blasting, the steel pipe rust removal grade can reach sa2 in gb / t 8923 - 1988 standard, and the surface roughness can reach r = 12.5 microns in gb 6060.5 - 88 standard. second floor: polyurethane insulation layer: a high-pressure foaming machine is used to inject hard polyurethane foam stock solution into the cavity formed between the steel pipe and the outer protective layer at one time, which is commonly known as " pipe - in - pipe foaming". third layer: high density polyethylene protective layer: prefabricated into black or yellow polyethylene plastic pipes with certain wall thickness. polyethylene is odorless, non - toxic, wax-like and has excellent low temperature resistance. the lowest temperature of use can reach - 70 ~ - 100 ℃. it has good chemical stability, can resist most acid and alkali attacks ( does not resist acids with oxidizing properties ), is insoluble in ordinary solvents at room temperature, and has small water absorption. however, because it is linear molecules, it can slowly dissolve in some organic solvents, and does not swell, and has excellent electrical insulation properties. its function is to protect the polyurethane insulation layer from mechanical hard objects, and to prevent corrosion and water. high density polyethylene polyurethane foam insulation steel pipe implementation: sy / t114 - 2000 and sy / t115 - 2001 standards.