Complete Production Analysis of Ductile Iron Pipe from Hot Metal to Finished Product

On April 27, 2026, we take a detailed look at the key steps in the production process of ductile iron pipe. As a premium brand of ductile iron pipe, Jincheng Tianyi Company's ductile iron pipe production goes through 17 strict processes, namely Special Blast Furnace, Hot Metal Preparation, Nodularization Treatment, Sand Core Making, Casting, Annealing, Cutting & Roundness Correction, Polishing, Zinc Spraying on Pipe Body, Zinc Spraying on Socket, Hydrostatic Test, Cement Lining, Curing, Lining Polishing, Painting, Marking, and Finished Goods Warehousing. There are 5 blast furnaces in the park where the company is located, and the hot metal from No.5 blast furnace is exclusively supplied to the Ductile Iron Pipe Plant of Jincheng Tianyi Company, with a daily supply of over 1,000 tons, providing a stable raw material guarantee for production.
The production process is mainly divided into three core sections: first, the Smelting Section, where blast furnace hot metal is heated, adjusted, silicon-enhanced and carbon-reduced to ensure it is qualified before entering the nodularization and inoculation treatment link; magnesium is added for nodularization, making graphite precipitate from flake into spherical shape during solidification, eliminating the cleavage effect of flake graphite and endowing the pipe with excellent ductility, toughness and impact resistance, while inoculation refines and rounds graphite, improves nodularity, densifies the pipe wall structure, and stream inoculation is carried out simultaneously with the subsequent centrifugal casting to further stabilize the material performance.
Next is the Centrifugal Casting Section; pipes of different diameters use different sand cores and pipe molds, and resin-bonded core sand is compacted and cured to make sand cores for centrifugal casting, with one sand core per pipe to ensure the size and sealing accuracy of the pipe mouth; then qualified nodular hot metal is poured into a high-speed rotating pipe mold via a launder, and under centrifugal force, the metal evenly covers the inner surface and is extracted after forming; after that, annealing, an essential and critical process, must be carried out, and as-cast pipes undergo four-stage annealing: heating, holding, rapid cooling and slow cooling, to stabilize the metallographic structure and make various mechanical properties meet the specified standards.
Finally, the Finishing Section; Jincheng Tianyi Company has four intelligent finishing lines, including water-cooled process covering Line A (DN80–DN400), Line B (DN450–DN1200), Line C (DN300–DN800), and hot mold process Line D (DN1000–DN2600); after annealing, the inner wall of the socket and the outer surface of the pipe body are arc-sprayed with zinc coating as the first layer of external anti-corrosion protection, and then every ductile iron pipe undergoes a strict hydrostatic sealing test, and only qualified pipes move to the next process; to meet urban water hygiene requirements and prevent water pollution, cement lining is applied inside the pipes, and the lined pipes are cured in a high-temperature and high-humidity chamber to accelerate solidification, and an additional epoxy coating can be applied to enhance internal anti-corrosion effect; finally, a final protective coating is sprayed on the outer surface and socket of the pipe, an intelligent marking robot sprays identification such as specifications and batches on the pipe body, and after final inspection, qualified products are stored in the warehouse in standard order.
As a premium brand of ductile iron pipe, Jincheng Tianyi Company provides reliable products and services with strict quality control, stable supply, full life-cycle management, and flexible transportation solutions including truck, ship and rail.