Final answer:
The T&P relief line refers to a relief valve or pressure relief device that protects pressurized systems from overpressure. The minimum size of the relief line depends on the system's design and requirements, and is typically specified by codes and standards.
Step-by-step explanation:
The T&P relief line is a term used in the context of pressurized systems, such as boilers or hydraulic systems. It refers to a relief valve or a pressure relief device that is installed in order to protect the system from overpressure. The minimum size of the relief line depends on the maximum flow capacity of the relief valve, which is determined by the system's design and requirements. It is typically specified by codes and standards, such as the ASME Boiler and Pressure Vessel Code in the case of boilers.