When renovating and changing water, community water supply or farmland irrigation, it is often encountered that PE pipes (polyethylene pipes, good flexibility) and PVC pipes (polyvinyl chloride pipes, high hardness) need to be connected - but the two materials are not compatible, and they will leak directly with glue or hot melt, which must be solved by the "transition method". The following shares 4 practical connection methods, with key precautions, to help you avoid leakage pits.

1. Flange connection: suitable for large pipe diameter, high pressure scene

If it is a large pipe diameter above DN50 (such as the main water pipe of the community), or needs to withstand high pressure (such as gas, industrial water supply), flange connection is preferred. Operation steps:

1. Install "hot melt flange" for PE pipe (use a hot melt machine to weld the flange and PE pipe), and install "adhesive flange" for PVC pipe (apply PVC glue to stick to the end of PVC pipe);

2. Put a rubber gasket between the two flanges (choose temperature-resistant and corrosion-resistant, such as nitrile rubber);

3. Align the bolt holes on the flange and gradually tighten it diagonally with stainless steel bolts (to avoid uneven force causing the gasket to deviate).

has the advantages of strong pressure resistance and long life, but the disadvantage is high cost and space occupation, which is suitable for outdoor projects.

Second, special adapter: the most commonly used "lazy method"

household or small and medium pipe diameter (DN20-DN40) is the most recommended - buy ready-made "PE-PVC conversion direct", one end is PE socket (can hot melt PE pipe), the other end is PVC socket (can stick PVC pipe). The steps are super simple:

1. Confirm that the joint specifications are consistent with the pipe (such as the PE pipe of φ 20 with the adapter of φ 20);

2. Clean the oil/burr of the PE pipe end and the PE end of the joint, and use a hot melt machine to weld the two (the temperature is adjusted to about 220 ° C, and the insertion depth is subject to the marking);

3. Clean the PVC pipe end and the PVC end of the joint, apply a layer of PVC special glue (to be evenly coated), rotate 1/4 turn after insertion, and keep it fixed for 10 seconds.

This method is compatible and fast to operate, and can be used in 90% of household scenes.

3. Threaded connection: Small pipe diameter is easy to disassemble

If it is a small pipe below DN20 (such as water pipes of water purifiers and water heaters), choose a threaded adapter - one end is PE internal thread, and the other end is PVC external thread (or vice versa). Steps:

1. Wrap 3-5 layers of raw material tape clockwise at the thread (avoid loosening when screwing);

2. Screw the PE pipe into the PE end of the joint (tighten it by hand, and then screw it half a turn with a wrench);

3. Screw the PVC pipe into the PVC end of the joint, and do not use too much force (to prevent slipping).

The advantage is that it can be disassembled repeatedly, which is suitable for scenarios that require frequent maintenance (such as changing the filter element of the water purifier).

Fourth, hot melt + glue combination: emergency use (not recommended for long-term)

If the adapter cannot be found temporarily, you can use "PE direct + PVC direct + transition pipe" emergency: For example, first heat melt the PE pipe directly with PE, and then glue the other end of the PE directly with PVC glue, and finally stick the PVC pipe. But the sealing of this method is not as good as that of the special adapter, it is recommended to only do short-term emergency.

Key precautions: Avoid 90% of the leakage problem

1. Specifications must match: the nominal diameter of the joint (such as DN25) should be consistent with the pipe, and the wall thickness should also correspond (such as PE pipe SDR11 corresponding to the wall thickness 3.7mm, PVC pipe PN1.0 corresponding to the wall thickness 2.0mm), to avoid inserting too loose or too tight;

2. Cleaning is the foundation: the oil, soil and burrs of the nozzle must be wiped clean (with alcohol or dry cloth), otherwise there will be gaps in hot melt or gluing, resulting in water leakage;

3. Must do stress testing: After connecting, use a pressure pump to hit 1.5 times the working pressure (such as household tap water pressure 0.3MPa, hit 0.45MPa), keep it for 30 minutes - the pressure does not drop, and the joint does not seep water to pass;

4. Leave expansion and contraction amount: PE pipe thermal expansion and contraction is larger than PVC. When connecting long distances (such as more than 10 meters), leave 5-10mm expansion and contraction space near the joint to avoid temperature changes and cracking the joint.

Finally summarize

The core of the connection between PE and PVC is to "find transition parts" - choose flanges for large pipes, conversion joints for small pipes, and temporary threads. Remember: sealing gaskets, raw material belts, and stress testing are three "life-saving steps", and no matter how urgent it is, you can't save it. Do it according to the above method, it will basically not leak!