The water-supply pipelines of PP-R and PVC-U are internationally mating advanced and new-typed energy-saved products in 90’s. They have the following advantages: 1) Light: the density is 0.89-0.91g/cm. which is one tenth that of steel pipes. Therefore the cost of transportation will decrease and the labor intensity of installation will be reduced.

2) Sanitary and non-poisonous: The raw materials are composed of only two chemical elements of carbon and hydrogen without any poisonous stabilizer of heavy metal salt. And the examination of the raw materials in sanitary has been passed by the state authoritative department.

3) Heat-resistant: The working water temperature is 70 degrees and the softening temperature is 140 degrees.

4) High impact-resistant: The annular rigidity is 1.3 times harder than that of the other solid pipes.

5) Long lifespan: The pipes can be used for over 50 years under the given pressure and temperature with properties of anti-ultraviolet rays and anti-radiation which would make them not fades.

6) Corrosion-resistant: They are resistant against corrosion from many of chemical agents except few of hydrogenated agents. And they have good properties of acid-resistance, alkaline-resistance and corrosion-resistance. They will never get rusty and breed bacteria and never be corroded by the electrochemistry.

7) Heat-retaining: The coefficient of heat conduction is low. At a temperature of 20 Celsius degrees the coefficient of heat conduction is 0.21-0.24w/mk that is much lower than that of steel pipes (43-52w/mk) and copper tubes (333w/mk). So they have good heat-retaining properties.

8) Small expansion obstruction: Because of the small elasticity the pipes will little expand with the change of the water temperature. They are suitable to be used in walls and floors.

9) Small water-flow obstruction: The inside of the wall of the pipe is smooth. The coefficient of the hindrance is only 0.007 that is much lower than that of steel pipes. The water-flowing volume increases 30 percent as against that of metal pipes of the same specifications.

10) Solid connection: The pipes are connected by way of heat-melting and adhesion. The intensity in the connecting section is stronger than the pipes themselves. Thus the leakage will never happen.

11) Environmental protection: The environment will not be polluted in course of the production and installation.

12) Complete specifications: The full specification of pipes and fittings can satisfy the demand of general civil engineering.

13) Moderate price: The price of the pipes of PP-R and PVC-U is almost the same as that of zinc-plated pipes. What is more, it is convenient for the laying land installation. So the cost is even lower.