Aboard small passenger vessels, which material may be used for diesel fuel line installations but not for gasoline fuel lines?

Correct Answer: Option D — Seamless steel pipe or tubing

46 CFR 182.440 prohibits the use of seamless steel pipe or tubing for gasoline fuel lines due to the risk of corrosion and vibration-induced cracking. However, these materials are permitted for diesel fuel systems, which operate under different pressures and are less susceptible to the specific hazards of gasoline.