Which statement describes the steel piping types explicitly listed as acceptable for propane vapor distribution by NFPA 58?

• A. Black iron, galvanized steel, or wrought iron
• B. Copper, stainless steel, or aluminum
• C. PVC, CPVC, or PEX
• D. Aluminum, brass, or nickel alloys

Answer: (A)

NFPA 58 for propane vapor distribution specifies steel-based piping as acceptable, specifically black iron, galvanized steel, and wrought iron. These materials are chosen because they can safely contain propane at distribution pressures, resist the mechanical stresses of installation, and provide reliable, leak-tight joints with gas-rated fittings. Galvanized steel offers corrosion resistance for outdoor or buried sections, black iron is the standard indoor piping material, and wrought iron covers older installations. Other materials like copper, stainless steel, aluminum, or plastics (PVC/CPVC/PEX) are not listed by NFPA 58 for propane vapor distribution, so they don’t meet the standard for this use.