Material received at site shall be inspected and stored according to manufacturer recommendations. Material shall be stored in a covered and dry space. During the unloading of the HDPE pipes adequate manpower shall be used to unload the pipes. and the piping and accessories shall be protected and covered with polythene sheets before installation.
Tools Required for HDPE Piping Installation
- Mechanical hand tool
- Cutting Tools
- Drilling Machine
- HDPE butt fusion and welding machine
How To Install HDPE Pipes
- Suitable lifting equipment i.e. crane or forklift shall be used to shift the pipes from stored place to the installation site. All necessary safety precautions as per established safety procedure shall be implemented during shifting and installation.
- The pipe lengths shall be cut according to the approved shop drawing, and shall be joined using butt fusion welding and electro-fusion welding as applicable.
Jointing of HDPE Piping
Smaller diameter HDPE pipes i.e. up to 75-mm will be joined using the hot plate welding, while the pipes above 75-mm shall be joined using a butt fusion machine and as recommended by butt welding machine supplier.
HDPE Electrofusion Welding
For HDPE electro-fusion welding, HDPE accessories are provided with spigot ends. The spigot ends are provided with low irregularities and the welding sleeve has projections to allow their exact distance apart to be determined.
- The HDPE electro-weld sleeve is provided with 2 socket ends which can be welded in a single operation.
- The welding equipment sends current through the resistance wires in the electro-weld socket for a set period. Both electro-weld sockets are welded at the same time.
- The electro-weld socket has stops on the interior. The socket has two contact pins on the outside for the connection of the welding equipment.
- There are two welding indicators which appear during and after the welding operation. These indicate that the welding has been reached and that the welding pressure has been applied.
- The connector cables from the welding equipment should be connected to electro-weld socket.
- This will illuminate “connection” indicator lamp.
- Press the start button. The welding indicator lamp will illuminate. Once the welding time is complete the lamp automatically extinguishes and the current supply switches off.
- Check the weld indicators. They should have emerged by around 2mm.
But Welding Of HDPE Pipes
In butt welding (pipes 75mm and smaller) both pipe ends are placed against a hot plate at a constant temperature and pressure. The plastic pipe ends are now pressed together so that the molecules of the material are transferred between them. Before starting hot plate welding the equipment shall be checked for the following items:
- The hot plate temperature must be 210 C.
- The hot plate must be clean and free of grease.
- Ensure that the two pipe brackets and the two pipe supports are correctly aligned.
- Both pipe clamps must be adjusted so that they hold the pipe tightly enough to withstand the force of the welding process.
- Press the pipe ends against hot plate by briefly applying a high pressure. Continue heating very low pressure until an up stand of 1 mm has formed.
- Quickly remove the hot plate and slowly increase the welding pressure.
- Hold the welding pressure steady and allow the weld to cool.
- Remove the joint and inspect the weld. An irregular weld seam should be rejected.
Install the pipe according to approved shop drawing. The installed pipe shall be inspected by the consultant. After approval for installation, pipe shall be hydro-statically tested.
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