For marine applications, all piping, valves, and fittings made of ferrous materials shall be protected inside and out against corrosion, except as permitted.

• A. Inside only
• B. Outside only
• C. Inside and out
• D. Not required

Answer: (C)

Marine environments expose ferrous piping to aggressive corrosion from both the inside and the outside. Moisture, contaminants, and condensate can attack the interior surfaces, while salt spray, humidity, and seawater contact attack the exterior. Protecting both surfaces helps prevent corrosion from progressing from either side, preserving the integrity of piping, valves, and fittings and ensuring the system remains safe and reliable. The clause “except as permitted” allows for approved alternative protections or material choices, but the default requirement is protection on both inner and outer surfaces.