In accordance with the international standard ISO 2531 and national standards GB/T 13295-2019 & GB/T 26081-2022, common C-class pressure ratings for ductile iron pipes include C20, C25, C30 and C40. Other pressure grades such as C50, C64 and C100 are also permitted.
C25 refers to an allowable working pressure of 2.5 MPa;
C30 refers to an allowable working pressure of 3.0 MPa;
C40 refers to an allowable working pressure of 4.0 MPa.
From August 25 to 27, the Cast Iron Pipe Subcommittee of the National Steel Standardization Technical Committee organized and held the official approval meeting for the national standard Ductile Iron Pipes, Fittings and Accessories for Water and Gas, together with the preliminary review meeting for Green Product Assessment - Cast Iron Pipes, in Qingdao City, Shandong Province. More than 50 committee members and expert representatives from 28 institutions attended the conference both on-site and online.
Hou Jie, Deputy Director of the Standards Institute of Metallurgical Industry Information & Standardization Research Institute, and Chen Jianbo, Chairman of the Cast Iron Pipe Subcommittee, attended the meeting and delivered speeches.
The meeting approved the revised national standard Ductile Iron Pipes, Fittings and Accessories for Water and Gas, which is undertaken by Xinxing Ductile Iron Pipes Co., Ltd. This standard replaces GB/T 13295-2019 and adopts the international standard ISO 2531:2009 with modifications. Compared with the previous version, it optimizes the classification system: the wall-thickness based K-class classification is cancelled, and the pressure-based C-class system is fully implemented. The C20 grade is newly added, and the product specification range is extended to DN3000.
Clear requirements for coatings are specified: for pipelines conveying drinking water, cement mortar sealing lining is recommended for DN300 and below to improve sanitary safety. This standard revision will promote resource-saving, green, low-carbon and environmentally friendly development of the cast pipe industry, accelerate the overall high-quality transformation of the sector, and lay a solid foundation for its long-term healthy development.
In addition, the conference conducted a preliminary review on the national standard Green Product Assessment - Cast Iron Pipes, jointly drafted by Xinxing Ductile Iron Pipes Co., Ltd. and Shanxi Xuanshi Industrial Group. Formulated based on GB/T 33761-2024, this standard covers ductile iron pipes and grey iron pipes, setting five primary indicators regarding resources, energy, environment, quality and low carbon, as well as industry-specific secondary indicators. Compiled in line with the principles of consistency and representativeness, it supports the national dual-carbon strategy and provides clear guidelines for the cast iron pipe industry in resource recycling, energy conservation, environmental improvement, quality upgrading and carbon footprint management. Relevant enterprise data will be collected and calculated in the next phase to prepare for the final approval of the standard.