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

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.