Polypropylene is not, polyethylene is not, polyethylene is not. There is no best, only the most appropriate. The scientific material selection method is to select the most cost-effective pipeline according to the characteristics and requirements of different application fields。
From the objective analysis of the technical indexes of PE-RT material, we believe that the material still has its advantages and certain market prospects: compared with traditional PEX pipe and aluminum composite pipe, PE-RT pipe not only maintains the characteristics of hot-melt connection, but also improves the thermal creep to a certain extent. If the material price is appropriate, it is expected that it does have a certain competitive advantage and market impact in the field of domestic floor radiant heating, but entering the building hot water market and high-temperature radiator heating market will attack each other with their own shortcomings.
First, heat resistance: compared with PP pipe and PE-RT, the ring stress of PE-RT material is lower than that of PP-R material. Heat resistance directly affects the application field of pipeline. It can be said that PE-RT material is not suitable for high temperature operation conditions at present. In view of this, some domestic enterprises began to learn from the forming principle of aluminum-plastic composite pipe and develop double hot-melt polyethylene RT aluminum-plastic composite pipe to improve the thermal strength of the pipe. This approach is far more responsible than unrealistic exaggerated publicity, but the products must also be strictly tested and recognized by the market.
Elastic modulus E: the elastic modulus of PP-R is 850mpa, PE-RT is medium density polyethylene, and the elastic modulus is about 550MPa. It has good flexibility and insufficient rigidity. It is used in the field of building water supply. The pipeline has poor straightness, is easy to bend and deform, and the pipeline is not beautiful.
Thermal conductivity: polypropylene-r is 0.24, polyethylene-rt is 0.42, and the height is nearly twice. If it is used for floor heating, this is its advantage. Good heat dissipation indicates better heat radiation effect. However, the use of hot water pipe is its disadvantage. If the heat dissipation is good, the heat loss will be great, the temperature of the pipe surface will be higher, and the hands are easy to burn.
Weldability: PP-R and PE-RT can be hot-melt welded, but PP-R is easy to operate, the edges of PP-R are round, the edges of PE-RT are irregular, and the welding temperatures that are easy to be blocked are also different. PP-R is 260 ℃, PE-RT is 230 ℃, and PP-R special welder sold in the market is adopted. In addition, due to the easy oxidation of polyethylene materials, special tools must be used to scrape the oxide scale on the surface before welding, otherwise the real integrated pipeline cannot be formed, and the pipeline is easy to leak, Construction is more troublesome.
Low temperature impact strength of polypropylene pipe: This is the advantage of polyethylene RT material in index. Polypropylene is stronger than polyethylene and polyethylene is softer than polypropylene. This is determined by the nature of the material. However, it is meaningless to exaggerate the cold brittleness of polypropylene-r. Polypropylene-r pipe has been used in China for more than ten years. Production enterprises gradually reduce the hidden dangers caused by improper handling to a minimum through effective packaging and strengthened publicity.
