Which element is crucial when determining the set pressure of a pressure relief valve?

The maximum allowable working pressure (MAWP) of the system is critical when determining the set pressure of a pressure relief valve. This is because the relief valve's set pressure should be lower than the MAWP to ensure that it operates effectively and safely before reaching potentially dangerous pressure levels. The MAWP establishes the upper limit of pressure that the system can handle in safe conditions, and the relief valve is designed to release excess pressure to prevent system failures or explosions.

While temperature of the fluid, type of fluid, and size of piping are important factors in overall system design and operation, they do not directly influence the set pressure of a relief valve in the same way that the MAWP does. The MAWP serves as a benchmark around which the safety and operational parameters, including the set pressure, are defined. The set pressure must be adequate to protect the system while complying with regulatory requirements and industry standards.