Final answer:
A T&P relief valve should be designed to perform at a specific set point temperature, slightly above the maximum normal operating temperature of the system, to ensure safety and prevent overpressure.
Step-by-step explanation:
A T&P relief valve should be designed to perform at a specific temperature known as the set point temperature. This temperature is determined based on the properties of the system and the desired safety requirements.
The set point temperature is usually chosen to be slightly above the maximum normal operating temperature of the system to ensure that the valve opens only when necessary to prevent overpressure.
For example, in a steam boiler application, the set point temperature may be chosen to be around 100°C.