基于正交试验研究燃气用聚乙烯管道热熔接头的冷焊缺陷

Research on cold welding defects of hot melt joints in gas polyethylene pipelines based on orthogonal experiments

以带冷焊缺陷的燃气用聚乙烯管道热熔接头为研究对象,采用正交试验方法制作热熔接头试样,利用多频微波检测试样的反射回波波幅,对试样进行拉伸试验,并采用扫描电镜观察拉伸后试样断口的形貌。结果表明:随着加热板表面温度的降低和吸热时间的减少,热熔接头的冷焊程度、冷焊长度及冷焊占比呈增大趋势,试样拉伸断裂时的最大拉力和位移呈下降趋势;热熔接头微观分子缠结程度与冷焊严重程度存在正向关系。

The hot melt joint of gas polyethylene pipeline with cold welding defects was taken as the research object.The orthogonal experimental method was used to make the hot melt joint sample.The amplitude the reflected echo wave of the sample was detected by multi frequency microwave,and the tensile test was carried out on the sample.The morphology of the fracture surface of the sample after stretching was observed using scanning electron microscopy.The results show that as the surface temperature of the heating plate decreased and the heat absorption time decreased,the degree,length and proportion of cold welding of the hot melt joint increased,while the maximum tensile strength and displacement at tensile fracture of the specimen decreased.There was a positive relationship between the degree of micro molecular entanglement in hot melt joints and the severity of cold welding.