延性铁管

Ductile iron appeared and developed since 1950s. It causes a a qualitative development in cast iron pipe’s propertis. Ductile iron pipe is not only corrosion proofing like the traditional cast iron pipes, but also with tenacity and good elongation.So it can be seen that ductile iron is with the advantages of both steel and iron. Centrifugal casting technology dramatically improve the producing efficiency and quality of ductile iron pipe. Its mechanical propertis is definitely better than other kind of pipes. Ductile iron pipeGray iron pipeSteel pipetensile strength≥420150 260≥400Elongation≥100≥18Solidity(HB)≤230≤210about140The properties of product submitted for bid Corrosion means the damage and degeneration of materials. The corrosion of metals compound metals is mainly caused by chemical and electrochemical damages with occasional chemical and biological forces. Because of its chemical composition, metallographic structure and installing structure, ductile iron pipe is more corrosion proofing than other kinds of pipe, which is illustrated by the following forms: 2.1 Drinking water flow corrosion experiment: Pipes for experimentCorrosion (g/cm2)45 days later90 days laterDuctile iron pipe0.00600.0090Traditional cast iron pipe0.00600.0103Welded steel pipe0.02940.03962.2 Seawater immersion Test Pipes for experimentTime& corrosionMg/dm2/daymm/yearPeriod of immersion90days180days360days90days180days360daysD I pipe24.016.113.20.1220.0810.066Cast iron pipe24.916.414.50.1270.0830.073Steel pipe30.220.727.30.1400.0970.130Notice: With time going on, corrosion will be reduced because of the substance resulting from corrosion, excluding steel pipes. 2.3 The excelent risistance of electrical corrosion Because of their high electrical resistance, and the rubber seal rings between them, ductile iron pipes are born with excelent resistance of electrical corrosion, which can protect themselves from electrical corrosion. 3. The advantages of cement lining of ductile iron pipe lies in two aspects: on one hand, it can make the pipe stronger to resist corrosion; on the other hand, it helps to keep the quality of water. Different from other kinds of protecting coating, cement mortar coating has hard surface. So even if there is a bit of microbe on it, it would never be damaged by the microbe’s corrosion. Technology of Products Submitted for Bid Centrifugal ductile iron pipe is made of ductile iron of high quality, in which sulfur takes up less than 0.025%,and phosphorus, less than 0.06%. This makes ductile iron much better than the first-grade pig iron. Ductile iron pipes are made by heating the blast furnace molten iron, hardening and tempering, nodularizing, casting, annealing, zinc spraying, hydraulic prssure testing, lining with cement, maintaining, internal grinding and print spraying,etc. Therefore, the products’tensile strength, elongation and corrosion risistance make ductile iron pipe the pipe with the highest ratio of performance and price.