What is the primary reason for installing a PSV downstream of a PRV?

The primary reason for installing a Pressure Safety Valve (PSV) downstream of a Pressure Relief Valve (PRV) is often related to safety and insurance compliance. When a PSV is installed, it acts as an additional layer of safety for pressure systems. In many instances, insurance companies mandate this setup to minimize the risk of equipment failure and prevent potential hazards. If a PRV were to malfunction, the PSV serves as a backup, ensuring that excess pressure is safely relieved, thereby reducing the risk of accidents that could lead to costly damage or injury.

In the context of regulations and industry standards, the requirements put forth by insurance companies illustrate their role in maintaining safe operational practices within facilities that rely on high-pressure systems. Although legal requirements and safety regulations are also important, the specific influence of insurance company policies can be significant in prompting the installation of a PSV in conjunction with a PRV, making this option the most pertinent explanation compared to others.

Enhancing system efficiency or controlling steam pressure pertains to operational performance rather than the primary focus of safety. Thus, while those aspects are significant in their own right, they do not capture the critical safety compliance focus that is often driven by insurance requirements and considerations for risk management.