Electrofusion welding is the process of joining two plastic pipes together using a single use coupler that has an integrated wire heating coil. The electrofusion control unit supplies electricity to this coil, heating it up and causing the plastic to melt. When this cools, a gas-tight joint is formed.
When the electric heating coil is energised, the plastic material touching it melts and forms an expanding pool of molten plastic which comes into contact with the surface of the pipe. The continued heating causes the pipe surface to melt and then mix with the molten plastic of the fitting. This mixing is vital to produce a good weld. Likewise, the correct delivery of energy to the heating coil is vital to create the molten plastic and allow the process to happen.
At the end of the heating cycle, the fitting and pipe are left to cool and the molten material solidifies to create a solid and sound joint. During this cooling phase, the joint must be kept completely still as movement can crack the interface and cause a leak path.
To ensure a good quality joint, the following need to be true:
- The heating coils need to be as close to the pipe/fitting interface as possible.
- The heat distribuiton is uniform over the length of the “hot zone”.
- Melt pressure and temperature are accurately controlled.
- The heating coils are protected from damage prior to and during the welding.
The welding units produced by Advance Welding use microprocessor technology to ensure that the correct energy is applied to the electrofusion joint, giving the perfect weld. Units designed to weld gas fittings are fully approved to the Gas Industry Standards and are CE marked.