HDPE is a good pipeline, which should not only have good economy.

HDPE is a good pipeline, which should not only have good economy, but also have a series of advantages such as stable and reliable interface, material impact resistance, cracking resistance, aging resistance, corrosion resistance, etc. It is mainly used in municipal water supply and drainage: it is an ideal pipe to replace cast iron pipe and cement pipe; large-scale water conservancy project: water conveyance, sewage, etc.

1 Development of HDPE water supply pipe

In the water supply and drainage pipeline system, plastic pipes gradually replace the traditional pipes such as cast iron pipes and galvanized steel pipes, and become the mainstream use of pipes. Compared with the traditional pipe, plastic pipe has the advantages of light weight, corrosion resistance, small flow resistance, energy saving, simple and rapid installation, low cost and so on. It is loved by the pipeline engineering field. At the same time, with the rapid development of petrochemical industry and the continuous progress of plastic manufacturing technology, the output of plastic pipe is growing rapidly, and the product types are more diversified.

HDPE pipe is the second largest plastic pipe in the world after PVC-U drainage pipe. Medium or high density polyethylene pipes of PE80 and PE100 grade shall be used for gas transmission; medium or high density polyethylene pipes of PE80 and PE100 grade shall be used for water supply pipe, and pe63 has been gradually eliminated. In terms of water delivery, the fastest-growing is PE100 pipeline system, and the growth rate is expected to reach more than 10% in the next five years.

In Europe, HDPE pipeline has been more rapid development and application, HDPE pipeline gradually replaced the status of PVC-U pipeline as the main consumer pipeline. At the same time, HDPE pipes are gradually used outside Europe.


2 Specification and connection mode of HDPE pipe

The diameter of HDPE pipe is from DN32 to DN1000, with a total of 26 grades. The pressure level is between 0.6MPa and 1.6Mpa, 5 levels in total.

HDPE pipes will be melted between 190 and N240 . With this feature, the two melted parts of pipes (or pipe fittings) will be fully contacted and kept at a proper pressure. After cooling, the two can be firmly integrated. Therefore, the connection mode of PE pipe is different from that of U-PVC pipe. Generally, the electric fusion connection and hot fusion butt joint are used. According to the size of pipe diameter, they can be divided into: when DN 63, injection molding hot fusion socket connection is used; when DN 75, hot fusion butt joint or electric fusion socket connection is used; when connecting with different materials, flange or screw connection is used.

In the pipeline repair method, there are expansion pipe construction method and lining HDPE method.

3 Application field of HDPE

HDPE pipeline is mainly used for: municipal engineering water supply system, indoor water supply system of buildings, outdoor buried water supply system, residential quarters, plant buried water supply system, old pipeline repair, water treatment engineering pipeline system, garden, irrigation and other industrial water pipes.

However, it should be noted that HDPE pipes cannot be used for hot water pipes.

4 Advantages of HDPE water supply pipeline in application

HDPE water supply pipeline is widely used, mainly because it has advantages that other pipelines can not compare:

1. It is easy to form a closed anti-seepage system by butt welding and electrofusion welding. When laying along the trench, the earthwork volume of trench excavation and the consumption of accessories can be reduced.

2. Light weight and easy to install;

3. Strong wear resistance and excellent hydraulic performance, no need for outer protection in buried pipeline. It can be used in the area of earthquake and subsidence of soil layer in mining area, and can also be laid at the bottom of river by sinking method.

4. Resistant to chemical corrosion, internal, external and microbial corrosion, strong corrosion resistance and health. It is suitable for transporting acid and alkaline substances, sewage, natural gas, gas and other substances;

5. Good environmental adaptability and frost resistance. It can be used for indoor and outdoor water supply pipes.

6. It has a long service life of more than 50 years;

7. Easy to recycle.

5 Matters needing attention in application of HDPE water supply pipeline

1. Outdoor laying, where there is sunshine, it is recommended to take shelter measures.

2. For buried HDPE water supply pipeline, the pipeline with DN 110 can be installed in a slightly serpentine way in summer, and the pipeline with DN 110 can resist thermal stress due to sufficient soil resistance, so it is unnecessary to reserve the pipe length; in winter, it is unnecessary to reserve the pipe length.

3. When installing HDPE pipeline, if the operation space is too small (such as pipeline well, construction in ceiling, etc.), electric fusion connection shall be adopted.

4. During the hot melt socket connection, the heating temperature shall not be too high or too long, and the temperature shall be controlled at 210 ± 10 , otherwise, the molten slurry extruded in the fittings will be too much, and the inner diameter of water will be reduced; during the socket connection, the fittings or pipe joints shall be clean, otherwise, the socket will be disconnected and water leakage will occur; at the same time, the angle and direction of the fittings shall be controlled to avoid rework.

5. During butt fusion connection, the voltage is required to be between 200-220v. If the voltage is too high, the temperature of the heating plate will be too high and the voltage will be too low, the butt joint machine will not work normally; the butt joint should be aligned, otherwise, the butt joint area will not be enough, the strength of the weld joint will not be enough, and the crimping will not be correct; when the heating plate is heated, the pipe joint is not cleaned or heated There are impurities such as oil and sediment on the plate, which will cause the interface to be disconnected and water leakage; the heating time should be well controlled, the heating time is short, and the heat absorption time of the pipe is not enough, which will cause too small welding edge curling and too long heating time, which will cause too large welding edge curling, which may lead to faulty welding.

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