NFPA 58 allows for various materials and piping joints (threaded and welded) to be used in respect to liquid piping in dispenser stations; one type of piping that cannot be used for liquid piping is?

• A. Stainless Steel
• B. Copper
• C. Plastic
• D. Brass

Answer: (C)

Piping that carries liquid propane in dispenser stations must be metal because LPG is a pressurized, flammable liquid that demands a robust, leak-tight system. Metals like stainless steel, copper, brass, and other suitable steels provide the mechanical strength to handle the pressure, resist temperature fluctuations, and allow reliable threaded or welded joints for secure connections. Plastic piping, in contrast, is not approved for liquid propane piping in these stations because it can be susceptible to permeation, cracking, or degradation under LPG service, leading to leaks and safety hazards. So, plastic cannot be used for liquid piping in dispenser stations.