聚乙烯燃气管道热熔接头微波检测

Microwave Detection of Polyethylene Gas Pipeline Hot-melt Joint

介绍微波检测技术的检测原理和技术特点。制作正常热熔接头试件,模拟施工现场可能导致缺陷产生的情况,制作缺陷热熔接头试件。对聚乙烯热熔接头试件进行微波检测,通过拉伸试验进行验证。聚乙烯热熔接头试件的微波检测结果与拉伸试验结果一致性较高,验证了微波检测技术对热熔接头内部缺陷的检测准确性。尽管采用正常工艺焊接热熔接头,但是微波检测结果显示存在局部缺陷,缺陷位置的拉伸试验断口呈现脆性断裂,说明正常工艺焊接过程中也存在不确定因素,会导致接头局部缺陷。合格的热熔接头微波检测图像显示为宽度及色彩均匀的条带。采用熔合面夹杂的焊接工艺,其微波检测图像表现为接头波动与局部缺陷,缺陷部位的拉伸试验结果为脆性断裂或脆性、韧性混合断裂。微波检测技术具备施工现场应用的可行性,但是缺陷判定指标仍需通过大量实践确定。

The detection principle and technical characteristics of microwave detection technology are introduced.Normal hot-melt joint test pieces are made,the conditions that may lead to defects on the construction site are simulated,and defective hot-melt joint test pieces are made.The polyethylene hot-melt joint test pieces are tested by microwave and verified by tensile test.The microwave detection results of polyethylene hot-melt joint test pieces are consistent with the tensile test results,which verifies the accuracy of the microwave detection technology in detecting the internal defects of the hot-melt joints.Although the hot-melt joints are welded by normal process,the microwave detection results show that there are local defects,and the tensile test fracture at the defect location presents brittle fracture,indicating that there are also uncertainties in the welding process of normal process,which will lead to local defects in the joints.The microwave detection image of qualified hot-melt joints is displayed as a strip with uniform width and color.When the welding process with fusion surface inclusion is adopted,the microwave detection image shows joint fluctuation and local defects,and the tensile test result of the defect part is brittle fracture or brittle and ductile mixed fracture.The microwave detection technology has the feasibility of application in the construction site,but the defect determination index still needs to be determined through a lot of practice.