Which standard specification should cast iron components comply with for use in CNG service?

Cast iron components utilized in CNG service must comply with ASTM A 47. This specification outlines the requirements for castings that are intended for use in environments where they may be exposed to gases or liquids, making it particularly relevant for compressed natural gas applications. ASTM A 47 ensures that the cast iron material has the necessary mechanical properties, chemical composition, and quality which are vital for safety and performance under the specific conditions found with CNG.

The other standards listed, such as ASTM A 36, ASTM A 53, and ASTM A 243, pertain to different materials or applications. For example, ASTM A 36 pertains primarily to carbon structural steel, while ASTM A 53 covers pipe specifications for different types of transportation of gas and water, and ASTM A 243 does not specifically focus on cast iron used for CNG service. These specifications serve different purposes and do not fulfill the requirements for cast iron components designed for CNG systems.