Question 1645 Deck General

The correct answer is B) may only be used in non-vital systems. According to 46 CFR Subchapter T, rigid plastic and other nonmetallic piping materials may only be used in non-vital systems on inspected vessels. This means they cannot be used in systems that are critical to the safety and operation of the vessel, such as fuel lines, fire mains, or other vital systems. The regulations prioritize the use of more durable metallic piping in these crucial applications. The other answer choices are incorrect because A) rigid plastic is not universally preferable to steel pipe, C) the regulations do not allow them to replace metal pipe in all installations, and D) they are permitted for use on inspected vessels, but only in non-vital systems.