How to weld PE pipes

PE pipes are widely used in water supply, gas and other pipeline systems due to their corrosion resistance and good toughness. However, many late-stage water leakage and liquid leakage problems are due to irregular welding operations - seemingly simple "pipe receiving", in fact, there are many details. Only by mastering the correct welding method can we ensure the sealing and durability of pipeline connections.

First, you must prepare before welding. Check the pipes first: see if there are scratches or cracks on the surface of the PE pipe, and whether the pipe ends are deformed. At the same time, confirm that the specifications (pipe diameter and wall thickness) of the two pipes are the same to avoid lax welding due to size mismatch. In terms of tools, you need a hot melt welder (core tool), a special pipe cutter, a clean non-woven fabric or absorbent cotton, and a marker - don't cut the pipe with an ordinary knife, uneven cutting will directly affect the welding effect.

Next is pipe cutting. Cut with a pipe cutter perpendicular to the pipe axis to ensure that the end face is flat and free of burrs - if the cut surface is oblique or burrs, the welding area will be uneven during heating, and it is easy to leak later. After cutting, you can use a marker to draw a circle of positioning lines at the end of the pipe to facilitate alignment during subsequent docking.

The third step is cleaning treatment. Wipe the end of the pipe and the heating plate of the hot melt welding machine with a dry cloth, without leaving dust, oil or water - these impurities will act like a "isolation layer", hindering the fusion between the pipe and the pipe, even small particles that cannot be seen by the naked eye may lead to welding gaps.

Then enter the key heating docking link. First adjust the temperature of the heating plate of the hot melt welding machine to 200-230 ° C (the temperature of PE pipes of different materials is slightly different. Generally, the manufacturer will mark it. If there is no standard, choose the middle value). After the temperature stabilizes, press the end faces of the two PE pipes on the heating plate respectively - pay attention to the uniform force until a uniform "melting ring" appears at the end of the pipe (that is, a ring formed by the melted PE material after heating). The width of the fused ring is particular: for example, for a PE pipe with a diameter of 20mm, the width of the fused ring is about 1-2mm; for a large pipe diameter above 110mm, the fused ring should be 3-4mm. The heating time should also be calculated. For example, the 20mm pipe takes about 5-8 seconds, and the 50mm pipe takes about 15 seconds. The larger the pipe diameter, the longer the time. Don't worry. If the heating is not enough, the welding will not be strong.

After the heating is completed, quickly remove the heating plate (the action should be fast, not more than 1 second), and then quickly connect the end faces of the two pipes - when docking, the pipe cannot be rotated, but should be advanced in a straight line, pushed until the previously drawn positioning line coincides, and then maintain the docking pressure (fixed with the welding machine's fixture) Cool down can not save: 20mm tube takes about 2 minutes, 110mm tube to more than 10 minutes, did not cool well to move the tube, will just fused part of the tear.

Finally, the inspection after cooling. After cooling is completed, first look at the fused ring: is it evenly surrounded at the interface, is there one side thick and one side thin? Then touch the interface: is there a gap, bulging or skewed? If the fused ring is uneven or there is a gap, it means that the heating time is not enough or the docking is not aligned, and it has to be re-welded.

There are still a few precautions to keep in mind: when welding below minus 5 ° C, the pipe should be wrapped in thermal insulation cotton, otherwise the heat will dissipate too fast when heating; the hot melt welding machine should be preheated 10 minutes in advance, do not use the machine as soon as it is turned on; when docking, keep your hands steady and do not let the pipe shake - even a little deviation will affect the welding quality.

In fact, the core of PE pipe welding is "uniform heating + precise docking + full cooling", and each step cannot save details. The seemingly troublesome steps are all to avoid the trouble of digging the ground to repair the pipeline later - after all, the rework cost of the buried pipe is much higher than the careful operation in the early stage. As long as you follow the steps, even if it is the first welding, you can make an interface that meets the requirements.