A safety valve over 3 inches and over 15 psig shall have what type of inlet connection?

A safety valve that is larger than 3 inches and designed for use with pressures exceeding 15 psig must have a flanged or welded inlet connection. This requirement is primarily due to the increased size and pressure ratings of these valves. Flanged or welded connections provide a stronger and more reliable seal compared to other types of connections, such as threaded. This is crucial in applications involving high pressures, where mechanical integrity is essential to prevent leaks or failure of the valve.

Flanged connections allow for easier installation and maintenance, as the valve can be bolted directly to the piping system. A welded connection provides even greater robustness and is typically used in high-pressure or high-temperature installations where there might be high forces acting on the piping system. Both options ensure that the valve remains securely attached to the system, which is vital for maintaining safety standards in high-pressure environments.

This standard recognizes the potential hazards associated with the operation of high-pressure boilers, where failure can lead to catastrophic incidents. Thus, the recommendation for flanged or welded connections is an important safety measure in the design and implementation of high-pressure boiler systems.