高密度聚乙烯外护保温管的开裂原因

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。

Cracking causes of HDPE outer insulating pipe

In cold areas, the outer PE layer of precast directly-buried insulating pipe may crack during storage and construction process. This paper analyzes the cracking reasons of this HDPE in projects from different aspects, such as physical property, raw materials and formulations of outer pipe, forming processes like extrusion temperature, cooling speed, pulling speed etc., precast process of PE insulation layer, structure characteristics of insulating bending pipe, environmental temperature, and installation process, etc.. This paper gives the repair measures in field repair to cracked insulating pipe with viscoelastic tapes and hot shrink tapes, puts forward relative suggestions in selecting appropriate raw materials, controlling process parameters during the production process, controlling the feeding volume of PE foam, and enhancing the protection of HDPE outer layer, etc..