24 June 2025
Electrofusion welding is a method used to join polyethylene (PE) and polypropylene (PP) pipes. It works by applying an electric current to specialist fittings that have built-in heating coils. These coils heat both the fitting and the pipe surface, fusing them together to form a strong, reliable joint.
It’s a go-to technique for installing pipelines that carry water, gas, chemicals, and other utilities. Especially where space is tight or excavation needs to be kept to a minimum, electrofusion delivers dependable results.
With over 45 years’ experience, we design and manufacture specialist tools for plastic and metal pipelines used around the world – and provide training on how to use them. Based on the questions we’re commonly asked about electrofusion welding, we’ve created this essential, back-to-basics guide on this popular technique.
Electrofusion vs butt fusion: which should I use for joining PE pipes?
Both methods create strong, leak-proof joints, but the right choice depends on the project at hand.
Butt fusion involves heating the pipe ends and pressing them together to form a seamless joint. It’s typically used for larger diameter pipes in open, accessible spaces where there’s room to set up alignment and fusion equipment. The weld is strong and cost-effective, but it does require clean pipe ends, exact alignment and consistent wall thickness across the joint.
If you’re working with smaller to medium-sized pipes, short sections, awkward locations or areas where digging needs to be kept to a minimum, electrofusion is the best option for joining pipes. Electrofusion uses specialised fittings with embedded heating coils to fuse the pipes. Because the fusion happens within the fitting itself, it means this technique can handle slight variations in pipe wall thickness and can be used in tight spaces or trench work.
Simply put, choosing between electrofusion and butt fusion usually comes down to:
- Pipe size – Electrofusion is typically used for pipe sizes up to 710mm, whereas butt fusion is used for larger pipe diameters up to 2000mm.
- Pipe material – Electrofusion can be used to join different grades of PE pipes, e.g. joining MDPE to HDPE.
- Pipe structure – Electrofusion can be used to join pipes with varying wall thicknesses, as well as pipes with multiple layers.
- Pipe accessibility – Electrofusion is best suited to installations with minimal access, like trenches or around other pipes.
In short, use butt fusion when you have space and uniform pipes, and electrofusion when access is restricted or the layout is more complex.
How does electrofusion work?
Here’s a step-by-step breakdown of the electrofusion welding process:
1. Surface preparation
Clean the pipe ends and mechanically scrape off the outer oxidised layer using a proper pipe scraper. This ensures a clean bonding surface. Most specifications require circa 0.2mm to be uniformly removed, but it can vary depending on pipe size and welding specification.
2. Pipe alignment & fitting insertion
Use alignment clamps to hold the pipes and fitting in place. This keeps everything in the correct orientation during welding, and prevents movement from the energy applied to the electrofusion coupler.
3. Electrofusion welding
A control unit (also known as an electrofusion box) passes a current through the fitting’s internal coils. These coils heat up and melt the inside of the fitting and the outer pipe surface, forming a fused zone.
4. Cooling
Keep the clamps on during cooling. Premature movement can compromise the joint.
5. Testing
Once cooled, carry out pressure tests or non-destructive checks to confirm weld quality.
A brief history of electrofusion
Early polyethylene discoveries
Polyethylene (PE) was first stumbled upon in 1898 by Hans von Pechmann, and later in 1933 by Eric Fawcett and Reginald Gibson at ICI in Northwich, UK. By 1935, Michael Perrin at ICI developed the process further, leading to large-scale production by the late 1930s.
Commercial metal catalysts & HDPE
In 1953, Karl Ziegler introduced a catalyst enabling low-pressure production of high-density PE (HDPE), a breakthrough later recognised with the Nobel Prize .
PE in gas networks
PE pipes began appearing in US gas distribution around 1959, soon followed by the first UK gas installations in 1969 using butt fusion and socket connections.
Electrofusion arrives in the UK
While electrofusion was used in Europe from the mid-1950s, it emerged in the UK around 1975. British Gas experimented with its own “Gascoil” fittings and control box, though widespread adoption followed the introduction of commercial units from DuPont and European fittings.
Modern adoption & UK involvement
Through the 1990s and 2000s, the resilience, ease of installation, and lifespan of PE and its fusion methods made them standard across utilities. Electrofusion fittings are now produced worldwide, with standardized practices and tooling evolving to support consistent, quality installations.
For the full story, deep dive into our dedicated blog post: The History of Polyethylene & Electrofusion Welding.
What equipment do you need for electrofusion welding?
We’ve designed our electrofusion range to equip you for every challenge you’ll face on site. Whether you’re dealing with limited access or large diameter pipework, here are the tools you’ll need for reliable, repeatable and efficient electrofusion welding.
Electrofusion control units
Hy‑Ram offers a full suite of electrofusion control boxes, available to buy or hire. Our models cover the full gamut of pipe sizes and applications, from compact site-ready units to advanced systems with barcode scanners, job reporting and full calibration and repair services.
Pipe scrapers (PrepMaster & PatchMaster)
Proper surface prep is critical for strong electrode bonds. Our PrepMaster Mono and Multi scrapers, as well as our PatchMaster tools, deliver consistent scrape depths across PE pipe diameters from 20 to 710 mm. The rotating carbide-blade design makes for controlled, repeatable cleaning so you can be sure of airtight fusion.
Re‑rounding tools
For oval or deformed PE pipe (an issue that’s common with prolonged storage), we provide a range of pipe re-rounding tools from 16 to 710 mm. These tools restore the pipe’s circular shape, allowing for accurate alignment with electrofusion fittings.
Alignment clamps
Once you’ve prepped and straightened the pipes, our precision-engineered alignment clamps hold everything together during welding. These clamps can ensure accurate joint alignment, supporting the joint weld cycle correctly.
Hy-Ram Engineering has your next electrofusion project sorted
Electrofusion is one of the most reliable and versatile pipe-joining methods in modern utility work. Whether you’re building out a new water system or patching a gas main, it’s a technique that delivers strong, clean and lasting connections.
Want to talk equipment specs, hire options, training support or real-world case studies? Get in touch with our team; we’re here to help keep your projects running smoothly.
