In the medium and low pressure pipe network, ductile iron Pipe has safe and reliable operation, low breakage rate, convenient construction and maintenance, quick and excellent corrosion resistance. Disadvantages of ductile iron pipes: Ductile Iron pipe connection by human factors such as operating level, responsibility and other influential, construction is not as convenient as PE pipe. Advantages of PE pipe: PE pipe has good corrosion resistance, its resistance to inorganic property is much stronger than that of metal tube, so it is not necessary to be embalmed in the buried ground. The small-caliber PE pipe is superior to the steel pipe and ductile iron pipe in the performance price ratio. PE tube has the disadvantage: benzene, gasoline, carbon tetrachloride and other organic solvents on polyethylene has a certain effect. Organic solvents, if infiltrated into polyethylene, there will be swelling phenomenon, the physical properties of the decline, its pressure resistance, temperature change performance is poor.