How is the electric fusion of HDPE tube fused

Update:17-06-2020
Summary:

Electrofusion is a simple method of connecting PE pipes […]

Electrofusion is a simple method of connecting PE pipes when no butt welding is possible (such as adding valves, elbows and tees). Use prefabricated fittings that contain electric heating coils that melt the plastics of the fittings and pipes, thereby fusing them together.

 

Hot melt

 

The characteristics (such as melting time) of the parts to be welded are attached to the parts through labels. The fused control unit (ECU) provides the electrical energy needed to heat the coil. After the coil is energized, the material close to it melts to form an expansion pool. The expansion pool is in contact with the surface of the pipe. The continuously introduced heat energy causes the surface of the pipe to melt, resulting in mixing of the pipe melt and the pipe fitting melt. This is essential for leak-free welding. After the thermal cycle is over, the fittings and tubes are cooled and the molten material solidifies to form a strong joint.

 

After the coil is energized, hot and cold areas are formed, and some terms are also referred to as melting and freezing areas. The length of these areas is particularly important. Each zone ensures that the welding is controlled to the exact length of the accessory socket and that the melt pressure is controlled throughout the connection process. The precise control of the coil relative to the inner surface of the socket, the pitch and the position ensure a uniform heat distribution.

 

The basic fusion parameters: temperature, pressure, and time are controlled by the ECU, and the ECU settings are programmed to the tags marked on the accessories themselves to set these parameters.

 

At present, some small ECUs can be used for one person to perform electrofusion welding in the groove.

 

The effectiveness of electrofusion depends on the preparation of the joining surface, ensuring the surface to be welded; contact during welding and cooling cycles. Before melting, the surface of the pipe to be melted needs to be scraped to remove the surface oxide layer.

 

Pipe clamps can be used to limit, align and re-circulate the pipe during the fusion cycle.

 

Ready to connect surfaces

 

The pipe surface must be scraped with an appropriate pipe scraper in accordance with the pipe or fitting manufacturer's recommendations to remove the entire surface of the pipe to a depth of approximately 0.3 mm.

 

Metal files, wooden files, emery paper, etc. are not suitable as construction tools. After scratching, the scraped surface must be wiped with a cloth soaked in isopropyl alcohol according to the recommendations of the pipe or fitting manufacturer to remove dust residues. It is not recommended to use methylated alcohol, acetone, methyl ethyl ketone (MEK) or other solvents to wipe; scratch the surface. Before processing, the prepared surface must be completely dry.

 

Operating specifications, the welded joints are as strong as the pipes and can withstand all the loads applied during normal installation and operation.

 

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