Introduction

China's revised national standard GB/T 13295-2026 "Ductile Iron Pipes, Fittings and Accessories for Water and Gas Applications" has been officially released and will come into effect on March 1, 2027.

The new standard will fully replace the previous version and become the primary technical specification for water supply and gas pipeline systems. Its implementation marks a significant step forward in improving product quality, engineering safety, resource efficiency, and industry standardization.

Major Change: Transition from K-Class to C-Class System

One of the most significant updates in GB/T 13295-2026 is the complete removal of the traditional K-Class classification system.

Why Was K-Class Removed?

The K-Class system was primarily based on pipe wall thickness. While widely used for many years, it had several limitations:

• Excessive focus on wall thickness rather than actual operating pressure

• Potential material waste due to overdesign

• Difficulty matching pipe performance to specific project requirements

• Coexistence of K-Class and C-Class standards created confusion in the market

The new standard eliminates all K-Class-related provisions and establishes a unified technical framework based on the C-Class system.

Expansion of C-Class Applications

The revised standard significantly expands the application range of C-Class pipes:

• Maximum nominal diameter increased from DN2600 to DN3000

• Suitable for ultra-large water transmission projects

• Introduction of thinner wall classifications down to C20

• Improved material utilization while maintaining safety and reliability

This update supports both infrastructure development and national goals for energy conservation and carbon reduction.

Enhanced Quality Control Requirements

The new standard introduces stricter quality inspection requirements.

Previously, wall thickness compliance could be indirectly verified through weight control methods. Under GB/T 13295-2026:

• Pipe wall thickness must be directly inspected

• Weight-based verification methods are removed

• Manufacturing consistency requirements are strengthened

• Quality control standards become more rigorous

These measures are expected to improve the overall reliability and safety of underground pipeline systems.

Improved Drinking Water Safety with Epoxy Seal Coating

Public health protection is another key focus of the revised standard.

For smaller diameter pipelines commonly used in distribution networks, particularly DN300 and below, the standard recommends the use of epoxy seal coatings as an alternative to traditional cement mortar linings.

Benefits of Epoxy Seal Coatings

Compared with conventional lining systems, epoxy coatings provide:

• Excellent corrosion resistance

• Improved sealing performance

• Reduced risk of bacterial growth

• No impact on drinking water quality

• Enhanced protection against secondary contamination

These improvements contribute to safer and more hygienic water delivery in the final stages of municipal distribution networks.

Positive Impact on the Industry

The implementation of GB/T 13295-2026 is expected to generate several long-term benefits.

Standardized Market Competition

By establishing unified technical requirements, the new standard will:

• Reduce market confusion

• Eliminate substandard products

• Raise industry entry thresholds

• Encourage fair competition based on quality

Lower Project Costs

The pressure-based C-Class system allows engineers to select pipes more accurately according to actual operating conditions.

This helps:

• Reduce unnecessary material usage

• Avoid overdesign

• Lower overall construction costs

Supporting Green Development

The introduction of thinner-wall C20 designs and wider adoption of environmentally friendly coating systems aligns with China's carbon reduction and sustainable development objectives.

Enhanced International Competitiveness

The updated technical framework is more closely aligned with international engineering practices.

This will help Chinese ductile iron pipe manufacturers:

• Improve product competitiveness

• Expand export opportunities

• Strengthen participation in international infrastructure projects

Looking Ahead

Underground pipeline networks are often referred to as the "lifelines" of modern cities.

Thanks to their high strength, excellent toughness, corrosion resistance, and reliable sealing performance, ductile iron pipes continue to play a critical role in:

• Municipal water supply systems

• Natural gas transmission networks

• Irrigation and water transfer projects

• Urban infrastructure development

The implementation of GB/T 13295-2026 provides a stronger technical foundation for the future of pipeline engineering in China.

As the industry transitions toward wider adoption of the C-Class system, manufacturers, engineers, and project owners will benefit from improved efficiency, higher product quality, and more sustainable infrastructure solutions.

Conclusion

The release of GB/T 13295-2026 marks an important milestone for China's ductile iron pipe industry.

Key highlights include:

• Complete transition from K-Class to C-Class classification

• Expansion of C-Class applications up to DN3000

• Introduction of C20 wall thickness class

• Mandatory wall thickness inspection requirements

• Promotion of epoxy seal coatings for improved drinking water safety

• Stronger support for sustainable development and international competitiveness

With the implementation of the new standard in 2027, China's ductile iron pipe industry is expected to enter a new phase of high-quality, green, and technology-driven development.