At present, in the water supply and drainage pipeline system, plastic pipes have gradually replaced traditional pipes such as cast iron pipes and galvanized steel pipes into mainstream pipes. Compared with traditional pipes, plastic pipes have the advantages of light weight, corrosion resistance, low water flow resistance, energy saving, simple and quick installation, and low cost. They are favored by the pipeline engineering community. At the same time, with the rapid development of the petrochemical industry and the continuous advancement of plastic manufacturing technology, the output of plastic pipes has grown rapidly and the types of products have become more diverse. Moreover, plastic pipe has made great progress in the design theory and construction technology of the building, and accumulated rich practical experience, which has promoted the plastic pipe to occupy a very important position in the construction of water supply and drainage pipeline engineering, and Form an unstoppable development trend.
HDPE pipes and PPR pipes become the most commonly used plastic pipes for water supply pipes. The following polyethylene composite pipe manufacturers discuss the practical fields of HDPE pipes and PPR pipes.
Introduction to an HDPE pipeline and PPR pipeline
HDPE is a high-density polyethylene. The diameter of HDPE pipes ranges from DN16 to DN315 and is divided into 18 levels. The pressure level is between 0.25Mpa and 1.0Mpa, with a total of 4 grades.
PPR is a three-type polypropylene, and the diameter of the PPR pipe is from dn20 to dn110, which are divided into five series. The pressure rating is between 0.125 MPa and 2.5 MPa.
HDPE material composition
Polyethylene, the English name "polythylene" referred to as PE, is a thermoplastic resin obtained by polymerization of ethylene, which has excellent properties against industrial chemicals. According to the long-term hydrostatic strength of PE pipe, the pipe and its raw materials are strictly classified into five grades: PE32, PE40, PE63, PE80 and PE100. The medium and high density HDPE pipes of PE80 and PE100 are mostly used to transport gas and water.
PPR material composition
The PPR pipe is a type III random polypropylene tube. It is a copolymer of propylene monomer Propylene and ethylene monomer Ethene (Poly Propylene Random Copolymer). It is a new type of energy saving and environmental protection with the international level in the 1990s. Plastic products. PPR pipe is a new material.
Comparison of two pipeline advantages
(1) Advantages of PPR water supply pipe
In addition to the characteristics of light plastic, good strength, corrosion resistance and long service life, PP-R pipe is also non-toxic due to its own characteristics (the molecule contains only two elements of carbon and hydrogen, which will not cause damage to the human body. Any poisonous and auxiliary use is a well-deserved environmental health material), no rust, no scaling (smooth inner and outer walls, strong corrosion resistance, and little flow resistance to flowing liquid) heat resistance, antifreeze, heat preservation The waste can be recycled and used. Therefore, it can be used as a hot and cold water pipe, a pure water pipe and a drinking water pipe. It also has the following main features: 1 Heat resistance, heat preservation, and energy-saving products. PP-R tube Vicat softening temperature is 131.3 ° C, the maximum use temperature is 95 ° C, long-term (50 years) use temperature is 70 ° C. The thermal conductivity of the product is 0.24W / m ° C, only 1 / 2 thermal conductivity of steel 200, for hot water pipe insulation energy saving effect is excellent;
2 It is convenient and reliable to install. It adopts hot-melt connection and can complete a joint connection in a few seconds. It is connected with metal pipe and water machine with high-quality metal nickel-plated inserts, which is safe and reliable.
3 Easy to recycle.
(2) Advantages of HDPE water supply pipe
1 HDPE pipe material is non-toxic, non-corrosive and non-fouling, can effectively improve the water quality of pipe network; resistant to chemical corrosion, resistant to internal, external and microbial corrosion, strong corrosion resistance and health; HDPE pipe has good water hammer resistance The ability of pressure, the integral joint of the pipe and the HDPE pipe to effectively resist the underground movement and end load, greatly improve the safety and reliability of the water supply.
2 Easy to match welding and electrofusion welding to form a closed anti-seepage system. When laying along the groove, the amount of earthwork for trench excavation can be reduced and the amount of accessories can be reduced.
3 Light weight and easy to install;
4 Strong wear resistance and excellent hydraulicity, no outer layer protection is required in buried pipelines. It can be applied to earthquake and mining area settlements, and can also be laid at the bottom of rivers by sinking method.
6 Good environmental adaptability and frost resistance. Can be used for indoor and outdoor water supply pipes.
7 Long service life with a service life of more than 50 years;
8 Easy to recycle.
Both pipes are suitable as water supply pipes.
Three kinds of pipe shortcomings comparison
(1) Disadvantages of PPR water supply pipeline
1 There are few pipe specifications and accessories. The types of accessories and valves are not complete, and there is a problem of inconvenient connection with the metal door. Large gauge pipes currently have a maximum of dn110, no larger specifications. It is greatly affected by temperature.
2 Rigidity and impact resistance are worse than metal pipes and are easily damaged.
3 The construction equipment is advanced and complex, the construction process requirements are high, and the requirements for construction personnel quality and construction management. The street quality of hot-melt connection is related to the ambient temperature, heating time and joint pressure, and it is easy to deviate during construction.
4 The linear expansion coefficient of the pipe is large.
5 poor UV resistance. In the long-term exposure of the sun, the PPR pipe is prone to aging and reduces the service life.
(2) HDPE for PPR disadvantages:
1. The cost of PPR and HDPE is high, and the pipe is now acceptable with the constant promotion price, but the price of the pipe fittings is still too high.
2. HDPE cannot be used in hot water pipe networks.
These two types of pipes are widely used in water supply systems (except for fire water supply systems), and PPR pipes can be used for hot water pipes. The outdoor large-diameter water supply network uses HDPE pipes.