An electrofusion fitting (electrofusion or resistance-coil welding) joins PE pipes permanently, tightly and with full pressure resistance – the welded joint is just as load-bearing as the pipe itself. Heating coils embedded in the fitting body melt the material of pipe and socket as current flows, so that both fuse in a material bond. This electrofusion fitting guide shows you how to proceed step by step when welding PE pipe.
Electrofusion makes sense wherever a permanent, durably tight connection matters: with buried drinking-water and gas lines, in pressure irrigation, with well and pool systems, or where electrofusion fittings have to be installed in tight spaces with little freedom of movement.
Professional note: welding work on pressure lines – especially on drinking-water and gas networks – may only be carried out by trained personnel in accordance with DVGW GW 330. This guide explains the procedure correctly from a technical standpoint but does not replace training. Difficulty: demanding · Duration: depending on dimension approx. 15–40 min. including cooling · Pressure rating: up to PN 16 and above.
What you need
Material:
- PE pipe in the right dimension and pressure rating (see PE pipe pressure ratings PN/SDR)
- Electrofusion fitting (socket, elbow, tee, reducer) from the range of electrofusion fittings in exactly the right size
- Cleaning wipes with PE cleaner (Tangit, isopropanol or similar, evaporating without residue)
Tools:
- Scraping tool (rotary scraper) for evenly removing the oxide layer
- Electrofusion welding unit with barcode scanner
- Pipe cutter or fine-toothed saw for a right-angled cut
- lint-free cleaning wipes
- Re-rounding clamp / positioning aid (welding clamp) and marker pen
Safety & standards
Resistance-coil welding is governed by the guideline DVS 2207-1 (welding of thermoplastics, PE-HD). For supply lines, the DVGW code of practice GW 330 also applies: assembly and welding work may only be carried out by trained and certified personnel (PE welders according to GW 330).
Wear suitable PPE (protective gloves, safety goggles if needed) and work absolutely cleanly – dirt, grease or moisture in the welding zone is the most common cause of defective joints. Protect the welding point in wind, wet or cold and observe the permissible ambient temperatures as well as the manufacturer’s specifications for the respective fitting.
Step by step
- Cut to length: cut the PE pipe exactly at a right angle with a pipe cutter or saw. An angled cut prevents the pipe from sliding evenly to the stop in the socket.
- Scrape / remove the oxide layer: use the scraping tool to remove the oxidised outer layer of the pipe all around over the entire insertion depth. A continuous, even shaving is important – the bare welding surface must not be touched by hand. Never just sand it down with abrasive paper.
- Clean: wipe the scraped pipe surface and the inside of the socket with a PE-cleaner wipe and let the agent evaporate completely. This removes chips, grease and moisture from the welding zone.
- Mark: mark the insertion depth all around the pipe (measure the socket length to the centre). This lets you see whether the pipe is seated correctly and deeply enough after insertion.
- Clamp: push the pipe and fitting together up to the mark and fix both with the re-rounding clamp/positioning aid. The parts must remain stress-free and motionless throughout the entire welding and cooling process.
- Weld with barcode: connect the fitting’s contacts to the welding unit and scan the fitting’s barcode. The unit automatically reads out the welding time and voltage and logs the process. Start the welding process and wait until the unit reports the end.
- Observe the cooling time: let the connection cool completely in the clamp for the cooling time specified by the manufacturer or fitting barcode. Only then release the clamp and load the line – moving it too early destroys the still-soft joint.
Pressure test
After complete cooling, the pressure test follows to check tightness and strength. Pressurise the line slowly and in a controlled manner (test pressure according to standard and application, often 1.3 to 1.5 times the operating pressure) and hold the pressure for the prescribed test duration.
Watch the pressure curve on the gauge and check all joints for drips or pressure drops. A constantly held pressure confirms the tight connection. For drinking-water and gas lines, the pressure test must be documented in accordance with the relevant DVGW codes of practice. More on the design in the article PE pipe pressure ratings PN/SDR.
Common mistakes
- Oxide layer not scraped or scraped unevenly: the most common cause of leaking joints. Always use the scraping tool, never abrasive paper.
- Welding surface touched or soiled: grease, chips or moisture prevent clean fusing – after cleaning, do not touch the bare surface again.
- Cleaner not evaporated: residual moisture in the welding zone leads to pores and defects.
- Pipe not pushed in to the mark: too shallow an insertion depth weakens the connection.
- Cooling time shortened: if the clamp is released or the line loaded too early, the still-soft joint tears.
- Angled cut or stress in the line: both create uneven melting zones.
FAQ
When does electrofusion make sense over other connections?
Electrofusion fittings are ideal when a permanently undetachable, fully pressure-tight connection is required or when there is little room to align. Anyone looking for a detachable or low-tool solution will find the right alternative in the PE pipe connection comparison.
Do I really have to scrape off the oxide layer?
Yes, mandatorily. The oxidised outer skin of the pipe prevents clean fusing. It is removed with a scraping tool all around and evenly over the entire insertion depth – sanding is not enough.
How long does the connection have to cool?
The cooling time depends on the dimension and manufacturer and is specified by the welding unit via the fitting’s barcode. It must be observed in full before the clamp is released and the line loaded.
May I carry out electrofusion myself?
On drinking-water and gas lines, a qualification according to DVGW GW 330 is required. For the selection of the right fittings and standard-compliant processing, the expert advice from KLN is at your side.
Standards, planning & advice
Decisive are DVS 2207-1 for the welding method and DVGW GW 330 for personnel qualification. In addition, always observe the assembly specifications of the fitting manufacturer. For the overall planning of your outdoor system, our hub Planning your irrigation helps, and which connection method suits your project is clarified by the PE pipe connection comparison.
Are you unsure about the method, dimension or pressure rating? The expert advice from KLN supports you in selecting suitable electrofusion fittings and the standard-compliant design of your PE pipe connection.