Butt Fusion Welding
What is Butt Fusion Welding?
Butt fusion welding is the name given to hot plate welding of thermoplastic pipes.
Pipe ends are brought together in the chassis of a machine where two separate pipes ends are clamped, faced square and then brought together against a heater plate under pressure for a period of time that is calculated by the pipe size – the thickness off the pipe and the cylinder area of the machine.
The heating phase, sometimes referred to as the ‘bead up. Is where the pipe ends are pressed against a heated plate for a period of time.
This is followed by the ‘heat soak’ phase where the pressure is reduced to just hold the pipe ends on the hot plate. This allows time for the heat to soak into the material at the pipe ends.
After the heat soak phase, the hot plate is removed, and the pipe ends are brought together. The time taken to do this is called ‘change over’ and needs to be as short as possible. The final phase is the welding/cooling time predetermined subject to pipe diameter and wall thickness.
The welding process allows the technician to produce what are referred to as strings that can be anywhere from 24m up to 100m depending on the allowable work site. The pipe string is then introduced into the trench where it is joined together either by butt fusion or electrofusion welding.
What is Electrofusion Welding?
The electrofusion welding process involves the use of a moulded socket fitting containing an electrical resistive heating coil.
The prepared pipe ends are inserted into the sockets and clamped. An electric current is then passed through the coil for a pre-set time.
Heating of the surrounding polymer and heat transfer to the pipe wall takes place. Cold zones at the ends of the fitting contain the melt in the central section, allowing a high melt pressure to develop and the formation of a homogeneous joint.
The process is more commonly seen in trench to join strings and fittings together where butt welding was not able to be achieved efficiently. Each fusion solutions welding technician has a calibrated EF welding machine along with multiple rational peelers and pipe alignment tools to ensure a successful weld is achieved every time.
PE Weld Limited is a company that specialises in the supply and fusion of polyethylene pipe.
