Electrofusion Welding For PE-HD

In the electrofusion method, special fittings are used that contain an internal electrical heating coil that is connected, via terminals, to a source of direct current. The heat generated causes the inside surface of the fitting and the outside surface of the pipe to melt and interact, thus forming the joint. It is a practical system that provides for branches, bypasses, etc. without having to cut the main flow as well as testing of new installations before commissioning. It is a modern solution that is especially suited to the laying of networks and is based on the maximal utilization of Polyethylene’s inherent polymer characteristics.

Equipment Required

• All welding is done as per SABS 4427.
• Fusion welding machine
• Generator (if necessary)
• Clamping tools (if necessary)
• Clean Water of Clear Spirits lint free cloths

Electrofusion Procedure

• Cut pipe square and remove burrs.
• Thoroughly scrape the outer surfaces of each pipe and spigot fitting to remove the surface layer (oxidized layer) from the areas to be welded.
• Assemble the joint and ensure that both components to be welded are in contact with the centre register inside the coupling.
• The joint should be clamped in instances where self-clamping is not available to ensure positioning during welding.
• Electrofusion fittings are usually packaged in protective plastic and should not be removed unless a weld is to be performed. This ensures that the fittings are free from dirt or impurities.
• On commencement of an electrofusion joint, connect terminals to fitting. (In instance where a bar code is available, swipe reading pen of electrofusion machine to enter parameters.) Press START.
• Should this type of technology not be available, enter parameters as contained on bar code into equipment. Press START once all data has been entered. Allow for prescribed cooling times.

Electrofusion Sequence

The sectional drawings show the jointing sequence from energising the coil until completion of fusion. The whole cycle is electronically monitored by the electrofusion control unit (ECU).