What is the minimum wall thickness required for ductile iron service mains according to NFPA 24?

The minimum wall thickness required for ductile iron service mains, according to NFPA 24, is ¼ inch. This specification ensures that the pipes have adequate strength and durability to withstand the pressures encountered in fire service applications. Ductile iron is favored for its excellent mechanical properties, including higher tensile strength compared to other materials, making it suitable for underground installations where it can be subjected to various external loads, such as soil and traffic.

Using a wall thickness of ¼ inch provides a balance between structural integrity and the material’s lightweight characteristics, along with cost-effectiveness. If the wall were any thinner, it might risk structural failure or damage under pressure, while unnecessarily increasing thickness could lead to higher material costs without providing significant benefits in usual conditions. Therefore, the minimum thickness is established to ensure reliability and safety in fire service performance.