NEWS

2023

Production process of ductile iron pipe

1. Boiling water in blast furnace.
2. Quenching and tempering of molten iron in electric furnace. Refine low phosphorus and low sulfur molten iron and ensure that the content of carbon, phosphorus, and sulfur in the molten iron meets the requirements. The intermediate frequency electric furnace ensures the stability of molten iron composition through advanced analysis and perfect process control during the quenching and tempering process.
3. Spheroidization of molten iron. The hot metal produced by electric furnace is spheroidized by adding a spheroidizing agent, and the composition is adjusted to meet the process requirements. Each furnace of molten iron must undergo component analysis by a spectrometer to fully meet the requirements of centrifugal casting.
4. Core making.
5. Centrifugal casting. Centrifugal casting using a water metal process. After melting in the electric furnace, molten iron at about 1360 ℃ is continuously poured into a high-speed rotating pipe mold, and is cooled by water to solidify the molten iron to form a ductile iron pipe.
6. Weighing.
7. Annealing. It refers to slowly heating a ductile iron pipe to a certain temperature, holding it for a sufficient time, and then cooling it at a suitable speed. The purpose is to reduce hardness and improve machinability; Eliminate residual stress, stabilize size, reduce deformation and crack tendency; Refine grain, adjust structure, and eliminate structural defects.
8. Spray zinc. In order to further enhance the corrosion resistance of ductile iron pipes, it is necessary to spray zinc on the outer surface of the pipes. Adopt metal zinc spraying, and the material is metal zinc with a zinc content of more than 99%. To ensure the quality of zinc spraying, zinc spraying should be carried out when the pipe body still has a certain temperature after the completion of the heat treatment process.
9. Rounding and polishing.
10. Hydrostatic test. Hydrostatic testing shall be conducted on each ductile iron pipe in accordance with international ISO standards. In the event of leakage, the pipe shall be immediately scrapped, and all cast iron pipes shall not be welded or glued.
11. Cement internal coating.
12. Health preservation. Create appropriate temperature and humidity to continuously increase the strength of cement.
13. Asphalt spraying: After internal coating and curing, the zinc sprayed ductile iron pipe is heated, and then the imported asphalt paint is sprayed by the asphalt external coating machine under high pressure to increase the anti-corrosion ability of the ductile iron pipe.
14. Finished ductile iron pipe.