PPR & HDPE Socket Fusion: How to Get Joints That Never Leak
Socket fusion is simple, and that is why it gets rushed. Here is the process that gives you a joint as strong as the pipe.
What socket fusion actually does
You are not gluing. You heat the pipe outside and the fitting inside at the same time until both surfaces melt, then push them together and let them fuse into one piece of plastic. Done right, the joint is as strong as the pipe.
Before you heat anything
- Cut square. An angled cut fuses on one side only.
- Clean and dry both surfaces. Dust or water = a weak joint. Wipe with a clean cloth.
- Mark your depth on the pipe so you know how far to push — and so you can see if it slipped back.
Temperature and time
Set the machine to around 260°C and let it fully reach temperature — the ready light is not a suggestion. Heating time goes up with pipe size; the machine's chart is your guide, not your instinct.
| Too little heat | Surfaces do not melt — the joint pulls apart later, often under pressure |
|---|---|
| Too much heat | Plastic deforms, the bore narrows, material squeezes into the pipe |
The join
- Pull both off the dies and push together straight and immediately — you have seconds
- Do not twist. Twisting tears the melted layer apart. Straight in, that is it.
- Hold still while it sets. Let go early and it creeps back.
- A small, even bead all around means you got it right.
Look after the dies
The PTFE coating is what stops plastic sticking. Never scrape it with a knife or a wire brush — clean it with a cloth while it is still warm. Once the coating goes, plastic drags and your joints suffer. PTFE-coated dies
Kit
- PPR / HDPE Socket Fusion Welding Machine
- Temperature Controller — replaceable when the thermostat drifts
