Ductile Cast Iron Pipes, also known as spheroidal iron pipes or nodular cast iron pipes, are manufactured by high-speed centrifugal casting with molten pig iron No. 18 and above, after adding spheroidizing agents. They are ideal for conveying tap water and are a preferred material for water supply pipelines.
In many regions across our country, ductile iron pipes are used for medium and small diameter pipe connections, employing socket-and-spigot or flanged joint methods; ductile iron must possess superior seismic resistance and sealing properties for allowable limited angles.
The main components of ductile iron pipes include carbon, silicon, manganese, sulfur, phosphorus, and magnesium, among others.
Standard of Execution: International Standard ISO 2531:1998 and National Standard GB 13295-2008
Ductile Cast Iron Pipes, abbreviated as DIP or GGG pipes, are pipes produced by high-speed centrifugal casting using molten pig iron with a number 18 or higher, after adding nodulizing agents.
Ductile iron pipes are a type of cast iron pipe. In terms of quality, the spheroidizing grade of the cast iron pipe should be controlled at levels 1-3 (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 pearlite, featuring excellent mechanical properties, corrosion resistance, good ductility, and superior sealing performance. They are easy to install and are primarily used for municipal and industrial water supply, gas transmission, and oil transportation.
A certain number of spherical graphite are distributed on the ferrite and spheroidite matrix. The proportion of ferrite and spheroidite in the matrix varies depending on the nominal diameter and the required elongation. For small diameters, the spheroidite 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. The graphite in ductile iron exists in a spherical form, typically with a size of 6-7 grades. The quality requirement for the spheroidizing grade of the pipes is controlled at 1-3 grades (spheroidizing rate ≥80%), thereby significantly improving the material's mechanical properties, inheriting the essence of iron and the performance of steel. After annealing, the microstructure of the ductile iron pipes consists of ferrite plus a small amount of pearlite, with good mechanical properties.
Ductile iron pipes, commonly 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 primarily used for municipal and industrial water supply, gas, and oil transmission. They are the preferred 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 size of ductile iron pipes generally refers to the inner diameter while PE pipes refer to the outer diameter, ductile iron pipes can achieve a larger flow rate under the same specifications. In terms of overall installation and maintenance costs, ductile iron pipes offer a superior cost-performance ratio. They are lined with zinc spray and cement sand mortar for corrosion protection.
