Selection and quality control of hot melt connection method
The selection of the hot melt connection method mainly depends on the material grade and density of the plastic pipe. The connection method of the plastic pipe should also be based on the relevant regulations of the buried "Technical Regulations for Polyethylene Water Supply Pipeline" (GJJ101-2004). Most polyethylene pipes can be joined together by two hot melt methods. However, some high-density polyethylene pipes cannot be joined by a receiving method. When used in buried heat exchangers, polybutene is generally a socket connection. A strong joint can be obtained by using both connection methods properly. When the two connections are used properly, a strong joint is obtained, which is stronger than the pipe itself.
It should be noted that different plastics or different grades of plastic should not be welded together due to differences in melting point and service life.
In the construction, the visual inspection and the "back bend" test method are mainly used to detect the welding quality.
Visual inspection - observation with eyes. The cuffs should be solid and round, with a wide root. If the root is narrow and has a curled middle cuff, it may be caused by excessive pressure or too short heat absorption time; the "back bend" test method is to use the finger to press the outside of the cuff and bend the cuff outward. Observe whether there are micro-seam-like defects during the bending process. If there are any, the heating plate may have slight pollution: if conditions permit, the ultrasonic inspection system of the polyethylene hot-melt butt joint may be used, according to the inspection characteristics and the mechanical test. Correlate the analysis results and make judgments on the quality of welding.
