Final answer:
The statement is true; safety valves should not have discharge piping valves, ensuring unobstructed pressure release for safety purposes.
Step-by-step explanation:
The statement that "A safety valve may NOT have a valve on its discharge piping" is true. Safety valves are critical components in various systems, such as boilers and pressure vessels, designed to release pressure automatically when a predetermined pressure is exceeded, to prevent equipment damage or explosions. Safety guidelines and codes like the ASME (American Society of Mechanical Engineers) Boiler and Pressure Vessel Code often stipulate that no valves should be placed on the discharge piping of a safety valve. This is to ensure that the safety valve can perform its function without any obstruction that a downstream valve might cause. Additionally, in practice, any obstruction could jeopardize the safe operation of the pressure system and is therefore avoided.