What are the problems that may occur during the hot-melt butt welding process of HDPE butt fusion thread fitting

In the hot-melt butt technology, the forming problem of the welding interface is a key link that needs urgent attention. This problem is usually manifested as the geometry of the welding interface not meeting the design standards. Common defects include uneven curling and excessive thickness deviation. The generation of these forming defects is often closely related to the contamination or foreign matter residue of the welding end face, which leads to uneven heat distribution during the welding process. In addition, moisture or water vapor residue on the welding end face will also have a negative impact on the welding quality, which may form a leakage channel and reduce the reliability of the connection. Factors such as the ovality of the pipe not meeting the standard, the deviation of the fixture stroke, the insufficient melting temperature and pressure, and the short welding time may all lead to poor forming of the welding interface, thereby affecting the performance of the overall pipeline system.

Microscopic defects are also technical problems that cannot be ignored in the hot-melt butt process. Such defects are usually hidden inside the welding interface, manifested as cracks, insufficient penetration, etc. The causes of these defects may involve poor quality of the hot melt or deviation of the flow rate, resulting in a significant reduction in the quality of the pipe butt. At the same time, insufficient melting temperature or harsh conditions of the welding environment may also cause cracks and cracks in the welding interface. In addition, if the pipe end faces are not kept parallel or the welding process is not sufficient, the welding permeability will be poor, which will affect the strength and stability of the connection.

During the implementation of hot-melt butt welding, excessively high heating temperature or excessively long heating time may cause material degradation. This degradation is usually manifested as oxidation and carbonization on the surface of the pipe, which seriously affects the welding quality. Excessive heating temperature may cause thermal degradation of high-density polyethylene (HDPE) materials, significantly reducing its mechanical properties and sealing properties. Excessive heating time may cause excessive melting of the material, forming too much molten material, thereby affecting the strength and stability of the welding interface.

In addition, improper operation is also a common source of failure during hot-melt butt welding. For example, if the speed of the clamp is too fast or the temperature and pressure are set too high, the height of the welding interface may be too high or the width may be too large, which will artificially reduce the water flow section and reduce the design flow rate. At the same time, if the surface of the heating plate is not fully cleaned during the welding process, the entry of impurities will directly affect the welding quality and lead to a decrease in the strength of the connection.

In order to effectively prevent the occurrence of the above-mentioned failures, manufacturers and construction personnel need to take a series of preventive measures. First, it is very important to ensure the cleanliness and flatness of the welding end face to avoid contamination and foreign matter residue. Secondly, choosing the appropriate melting temperature and pressure to ensure the full fusion of the welding interface is the key to improving welding quality. In addition, strict inspection of pipes and fittings to ensure that their ovality, wall thickness and other parameters meet the design specifications should not be ignored. Construction personnel should receive systematic professional training and master the correct operating skills to ensure the stability and reliability of the hot melt butt welding process.