Why is the hot melt welding of PE pipe defective

Why is the hot melt welding of PE pipe defective

1.Analysis of welding defects of PE pipe hot melt welder

The PE pipe hot melt welding machine is applied in the installation of a pipe network project. The diameter of the main water supply pipe is greater than 63mm and the wall thickness is greater than 5mm. In the process of welding such pipe elements, the maximum water pressure of the pipe network is within 60m, and the welding precision can be ignored. However, in practical work, due to the mountainous area.If the water pressure required by the terrain is too high and the welding technology is not enough, some defects will appear, so it is difficult to improve its work level and quality and meet its work requirements.

1) Defects in welding forming.

In general, the defects of welded joint forming are mainly due to the deviation in crimping geometry and structure, which can not meet the relevant requirements.

First, if there are stains or foreign matters on the welding end face, it will lead to the deviation of the thickness of the welding wall on both sides. In the case of uneven heating, there will be asymmetry around the welding interface, and the size can not meet the relevant regulations, such as notch, gap and other defects.

Second, if the end face of the welding port is wet during welding, the port welding is not transparent and firm; Or there is water vapor, which will lead to welding quality problems and leakage channels.

Third, if the ovality of welded pipes does not meet the relevant regulations, the reliability of butt joint can not be guaranteed, and the problem of misalignment will occur.

Fourth, if the fixture stroke deviates, or when melting, the docking temperature and pressure are low and the welding time is short, the quality of the welding interface will be reduced. If the speed of the fixture is fast, or the temperature and pressure are high, the height of the welding interface is high or too wide, which artificially reduces the water flow section and reduces its design flow.

2) Micro defect problem.

Micro defects are quality problems in the welding interface, such as cracks, cracks, poor penetration etc.

First, if the quality of hot melt used by construction technicians is poor or there is deviation in flow rate, the butt joint quality of pipes will be reduced. For example, when the deviation in flow rate is greater than about 0.6g/10min, the quality defect of welding interface will occur. If the melting temperature is low or the welding environment is poor, there will also be welding interface cracks and cracks.

Second, in the actual construction, the end faces of the pipeline are not parallel, or the end faces are not fully welded by using the heater plate, resulting in poor welding permeability.

3) Microscopic defects.

In the actual welding work, due to the high heating temperature or long heating time, the pipe will be oxidized and damaged. In serious cases, carbonization will occur, followed by material deterioration. For welding defects, various problems are interrelated. If the operators and technicians lack technical ability and responsibility

Any sense of responsibility, failure to carry out relevant work according to equipment performance and welding requirements will gradually reduce the quality of welding engineering.

Post time: Aug-03-2021