In 1947, H. Morrogh of the United Kingdom found that the graphite was spherical when cerium was attached to peri-eutectic grey cast iron so that its content was above 0.02 wt%. 1948, A. P. Ganganebin of the United States and others pointed out that magnesium was added to the cast iron, followed by ferrosilicon breeding, and when the residual magnesium was greater than 0.04 wt%, spherical graphite was obtained. Since then, ductile iron has been produced on a large industrial scale. The history about the use of ductile iron pipes can be traced back to 1668 in the suburbs of Paris from the Seine to Versailles for the whole field of about 21.14Km water pipeline, 300 years have passed, except for some pipes and joints maintenance and replacement, the main body is still in use today.
China's ductile iron pipe industry started in the early 1990s and has developed rapidly under the strong support of the China Urban Water Supply Association. After nearly 20 years of practical use, its safety and practicality have been generally recognized by the water supply industry, and the annual domestic production has reached 2.2 million tons in 2008, which is 11 times of that in 1990. As China is a country lacking in water resources, at present, China's urban water supply capacity is obviously insufficient, and some cities have serious water shortage. Among the 668 cities in the country, there are more than 300 cities with water shortage, accounting for 46%; among them, there are more than 140 cities with serious water shortage, accounting for 21%, and the cause of water supply and water conservation is emerging, and ductile iron pipes have a broad development prospect.
Bitumen paint coating is used for pipelines carrying gas. Preheating of the pipe before painting can improve the adhesion of the bitumen paint and accelerate drying.
This internal anti-corrosion measure is used for pipes conveying sewage and can improve the corrosion resistance of the lining.
Epoxy coal bitumen coating is suitable for both gas and sewage pipelines. It is a two-component coating, the coating has high adhesion and very smooth surface
Epoxy ceramic lining is suitable for sewage and gas pipelines, but has limitations in use due to the difficult manufacturing process and high cost. Epoxy ceramic lining has high adhesion and finish, and is a good anti-corrosion coating.
Both of these two special cement coatings are suitable for the internal corrosion protection of ductile iron pipes for sewage pipes to improve the resistance to the erosion of acid and alkali components in sewage.
It is a new type of green special coating developed to meet the needs of environmental protection, with good wear and corrosion resistance.
The above information is provided by the ductile iron pipes supplier.
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