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在寒冷地区,预制直埋式保温管在储存和施工过程中会出现聚乙烯外护层开裂现象。针对高密度聚乙烯外护保温管开裂的工程实例,从保温管材料的物理性能,外护管原料及配方,挤出温度、冷却速度、牵引速度等成型工艺,聚氨酯保温层的预制过程,保温弯管的结构特点,环境温度以及施工过程等方面,全面分析了可能导致高密度聚乙烯外护保温管开裂的原因。介绍了采用粘弹体胶带和热收缩带对现场已开裂保温管的修复补救措施,提出了选用适宜原材料、严格控制生产过程工艺参数、控制聚氨酯泡沫投料量以及加强高密度聚乙烯外护层保护等建议。
In cold areas, the prefabricated buried pipe insulation during the storage and construction of polyethylene sheath cracking occurs. According to the engineering examples of high temperature polyethylene pipe insulation cracking, from the physical properties of the insulation pipe material, raw materials and formulations of the outer sheath, extrusion temperature, cooling rate, traction speed and other molding processes, polyurethane insulation layer prefabrication process, insulation Elbow structural characteristics, ambient temperature and construction process, a comprehensive analysis of the reasons may lead to high-density polyethylene insulation pipe cracking. The repairing and remediation measures of cracked insulation pipe on the site by using the viscoelastic tape and heat shrink tape are introduced. The suitable raw materials, the process parameters of the production process are strictly controlled, the dosage of polyurethane foam is controlled, and the protection of high density polyethylene outer sheath is strengthened Other suggestions.