Section 5.4.1/Gas Piping Materials and Components
NFPA 54 Chapter 5 covers approved gas piping materials, fittings, valves, and component specifications for fuel gas systems.
Gas piping must use approved materials listed in Chapter 5. Common approved materials include black steel pipe (Schedule 40 for most applications), corrugated stainless steel tubing (CSST) listed to ANSI LC 1/CSA 6.26, copper tubing (Types K and L for exterior, Type L for interior), and polyethylene (PE) pipe for underground exterior use only. Valves must be approved for fuel gas service. Each piping material has specific joining methods: threaded or welded joints for steel, listed fittings for CSST, brazed or flared joints for copper. Materials not listed in Chapter 5 are prohibited.
Why this section exists
Natural gas and propane are flammable and potentially explosive. Only materials tested and proven for gas service are permitted. Standard plumbing materials (PVC, ABS, galvanized steel) are not approved for fuel gas because they may degrade, leak, or fail under gas service conditions. The specific joining method requirements prevent leak- prone connections. CSST, while convenient, requires specific listed fittings and bonding because of its vulnerability to lightning damage.
What plan reviewers look for
Plan reviewers check the gas piping specification for approved materials. They verify the pipe material matches the application (PE only outdoors underground, copper only with approved gases). They check that joining methods are specified and appropriate for the material. For CSST, they verify the manufacturer and listing are specified.