31 March 2026
Butt fusion machines are used to weld gas and water pipes together, particularly those made from thermoplastic materials, such as polyethylene. This type of welding is a technique that can create highly durable, permanent joints without the need for additional fittings or ancillary items.
In this quick guide, we’ll cover the steps involved to operate a butt fusion machine, including how the pipes should be prepared, as well as handy tips for a perfect weld and smooth operation.
Preparation & checks
Firstly, the inner and outer surfaces of the pipe ends must be cleaned to ensure that there is no dirt, oxidation, imperfections, or contaminants. This can impact the quality and longevity of the weld. You can use a clean, damp lint-free material or isopropanol wet wipe. Be sure to wipe both the inner and outer surfaces and allow all surfaces to dry fully after.
The two pipe ends must also be trimmed. Make sure that all loose shavings are removed from in and around the jointing area. Do not touch the shaved areas as this may contaminate the surface and affect the overall weld quality/integrity.
Alignment and pipe slippage should then be checked. Simply bring the pipe ends together and visually check that the outside pipe diameters are within the following limits:
- Less than 1mm up to and including 180mm
- Less than 10% of wall thickness above 180mm
Source: WIS 4-32-08, June 2016: Issue 4 (Amendment August 2023)
If the measurements are greater than the above, they should be realigned and re-trimmed.
Our WeldMaster butt fusion machine has an automated pipe slippage and alignment check prompt as part of its welding software program, with supporting details and animated user guidance.
Step 1: Bead Up & Soak
After all checks are completed, the pipe ends are held against a heating plate until they become soft and pliable at a specific bead size. This phase is called bead up and the WeldMaster carefully controls the key parameters such as temperature, pressure and time to ensure that this is all completed within the welding specification selected.
After bead up, the pressure is dropped between zero drag pressure, which controls bead growth and allows the heat to soak into the material.
Step 2: Dwell
Here the chassis must open, the heater plate is removed and the chassis closes again to bring the pipes together. It is important that this is all completed in a controlled and timely manner, so as to maintain maximum weld quality and meet the selected weld specification.
The WeldMaster completes this phase accurately and promptly, maintaining high heat retention in the pipe ends, supporting weld integrity.
Step 3: Fusing
When the pipe ends are malleable and at the required temperature, they can be pressed together. The pressure used for this must be maintained for a specified time to allow the pipes to be properly and accurately welded together.
Step 4: Cooling
The joint must then cool in the machine whilst pressure is monitored and controlled. This is a crucial final step of the butt fusion welding process as it allows the new fused pipe to set in place. This is controlled by our fully automated WeldMaster system.
Once fully cooled, the joint will be as secure as a continuous length of original pipe.
Final tips & quality checks
Here are some important things to be aware of when using a butt fusion machine for pipe welding:
- Make sure to check the correct specified operating temperature, pressure, and timings for fusing and cooling periods. These elements differ for each pipe size, wall thickness, weld specification and type of thermoplastic material.
- Don’t operate the machine under challenging weather conditions (such as rain, fog, or snow), without suitable ground and equipment covering, or without using suitable PPE.
- Only those suitably trained should operate a butt fusion machine.
- Ensure that the work is being completed with a suitable ambient temperature.
- Make sure to keep an eye out for leaks and oil levels before each use, as these can impact machine performance.
- If the pipe ends come into contact with any contaminants after they have been cleaned and trimmed, this step must be repeated. Make sure to leave the pipe ends to dry before heating if you are using an isopropanol wet wipe.
Partner with Hy-Ram Engineering for high-performance butt fusion machines
Our butt fusion WeldMaster machines feature innovative functionality and automated operator interface to create long-lasting pipe joints. Support can be offered in relation to sales, hire, repair and training of our Butt Fusion Machines.
Get in touch with the Hy-Ram team today to discuss!
