According to 46 CFR Subchapter T, rigid plastic and other nonmetallic piping materials __________.

Correct Answer: Option B — may only be used in non-vital systems

Under 46 CFR Subchapter T, rigid plastic and nonmetallic piping are restricted to non-vital systems, such as drainage or non-pressurized water lines. They are prohibited in vital systems like fuel, fire main, or bilge piping due to their vulnerability to heat, fire, and mechanical impact compared to steel.