Centrifugal spheroidal iron pipes are made by casting iron water with a number 18 or higher, adding spheroidizing agent, and then centrifugally casting through a centrifugal spheroidal iron casting machine. These pipes are known as "Ductile Cast Iron Pipes," abbreviated as Ductile Iron Pipes, Spheroidal Iron Pipes, and Spheroidal Cast Iron Pipes, etc. They are mainly used for the conveyance of tap water and are an ideal material choice for water supply pipelines.

In many regions of our country, the connection between medium and small diameter pipe sections in water supply systems utilizes socket-and-spigot or flanged joints for cast iron pipes; spheroidal graphite cast iron must possess excellent seismic resistance and sealing properties for allowable restricted bending angles.

The main components of ductile iron pipes include carbon, silicon, manganese, sulfur, phosphorus, and magnesium, etc.

Standard of Execution: International Standard ISO 2531:1998 and National Standard GB 13295-2008

Ductile Cast Iron Pipes, commonly referred to as ductile iron pipes, spheroidal iron pipes, or spheroidal graphite cast iron pipes, are defined as pipes produced by casting molten pig iron with a spheroidizing agent at a casting temperature of 18# and above, then cast at high speed using a centrifugal spheroidal iron casting machine.

Ductile iron pipes are a type of cast iron pipe. The quality requirements call for the spheroidizing grade of the cast iron pipe to be controlled at 1-3 levels (spheroidizing rate >80%), thereby significantly improving the material's mechanical properties, combining the essence of iron with the performance of steel. After annealing, the microstructure of the ductile iron pipe consists of ferrite with a small amount of spheroidite, featuring excellent mechanical properties, corrosion resistance, ductility, and sealing performance. They are easy to install and are mainly used for municipal, industrial, and mining enterprises in water supply, gas transmission, and oil transportation.

A certain number of spherical graphite are distributed on the ferrite and pearlite matrix. The proportion of ferrite and pearlite in the matrix varies depending on the nominal diameter and the required elongation. For small diameters, the pearlite proportion is generally not more than 20%, while for large diameters, it is typically controlled around 25%.

Mechanical Properties

Minimum tensile strength: 420 MPa, minimum yield strength: 300 MPa, minimum elongation: 7%

Bore Size: DN80 - DN1600

Performance

Ductile iron pipes are a type of cast iron, an alloy of iron, carbon, and silicon. In ductile iron, the graphite exists in spherical form, generally ranging from 6-7 grades. Quality requirements dictate that the spheroidizing grade of the cast pipes be controlled at 1-3 grades (spheroidizing rate ≥80%), thereby significantly improving the material's mechanical properties. It retains the essence of iron while possessing the properties of steel. After annealing, the microstructure of ductile iron pipes consists of ferrite plus a small amount of pearlite, and they exhibit good mechanical properties.

Ductile iron pipes, primarily known as centrifugal ductile iron pipes, possess the essence of iron and the properties of steel. They offer excellent corrosion resistance, good ductility, superior sealing, easy installation, and are mainly used for municipal and industrial water supply, gas, and oil transmission. They are the top choice for water supply pipes due to their high cost-performance ratio. Compared to PE pipes, ductile iron pipes are simpler and quicker to install, with better internal and external bearing pressure after installation. In terms of tightness and corrosion resistance, ductile iron pipes provide better tightness and can enhance their corrosion resistance through various protective measures. From a hydraulic performance perspective, since the specifications of ductile iron pipes generally refer to the inner diameter while PE pipes refer to the outer diameter, ductile iron pipes can achieve greater flow rates under the same specifications. In terms of overall installation and maintenance costs, ductile iron pipes offer a superior cost-performance ratio. Zinc spraying on the inner wall and cement sand mortar for corrosion protection are also used.