How is HDPE Pipe Fused by Electric Fusion?
Electrofusion is a simple method to connect HDPE pipes when butt welding is not possible (such as adding valves, elbows, and tees). Use prefabricated fittings that contain electric heating coils that melt the plastic of the fitting and pipe, causing them to fuse.
Hot Melt Complaint For HDPE Pipe
Label the fittings with the characteristics of the fittings to be welded (e.g. melting time). The electrofusion control unit (ECU) provides the power required to heat the coil. After the coil is energized, the material near it melts to form an expansion pool. The expansion pool contacts the surface of the HDPE pipe. The continuously introduced heat energy causes the surface of the pipe to melt, resulting in a mixture of the pipe melt and the pipe fitting melt. This is crucial for flawless welding. After the thermal cycle is complete, the fitting and tube are cooled and the molten material solidifies to form a strong joint.
When the coil is energized, hot and cold zones are created, also known as melting and freezing zones in some terms. The length of these areas is particularly important. Each area ensures that the weld is controlled to the precise length of the fitting socket, ensuring melt pressure is controlled throughout the connection process. Precise control of the coil’s pitch and position relative to the socket’s inner surface ensures even heat distribution.
Basic fusion parameters: temperature, pressure, and time are controlled by the ECU. The ECU settings are programmed to set these parameters with labels marked on the accessory itself.
Some small ECUs now allow one person to perform electrofusion welding in the trench.
The effectiveness of electrofusion depends on the preparation of the joining surfaces, ensuring surfaces are welded; and contact during welding and cooling cycles. Before melting, the surface of the HPDE pipe to be melted needs to be scraped to remove the surface oxide layer.
HDPE Pipe clamps can be used to restrain, align, and re-circulate the pipe during the fusion cycle.
Prepare the Joining Surface
The HDPE pipe surface must be scraped with a suitable 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, wood files, emery paper, etc. are not suitable as construction tools. After scraping, the scraped surface must be wiped with a wipe soaked in isopropyl alcohol as recommended by the pipe or fitting manufacturer to remove dust residue. It is not recommended to use methylated alcohol, acetone, methyl ethyl ketone (MEK), or other solvents to wipe; or scrape the surface. The prepared surface must be completely dry before treatment.
Operating specifications, the fused joint is as strong as the pipe and can withstand all loads imposed during normal installation and operation.
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