For a boiler with two safeties and a MAWP of 60 PSI, where is the secondary safety set?

In a high-pressure boiler system, safety devices are critical for ensuring the operation remains within safe limits. The Maximum Allowable Working Pressure (MAWP) is the maximum pressure a boiler is designed to withstand under normal operating conditions. In this case, the MAWP is set at 60 PSI.

When determining the settings for safety valves, it is standard practice for the secondary safety device to be set above the MAWP but below a level that would cause undue stress or risk to the boiler system. A common industry practice is to set the secondary safety valve at a pressure that provides a margin above the MAWP, typically 10% for operational safety.

Calculating 10% of 60 PSI gives us an additional 6 PSI, leading to a setting of around 66 PSI. This establishes a safe buffer that allows for system fluctuations while protecting the boiler from overpressure situations. Therefore, the secondary safety being set at 66 PSI is accurate, as it fulfills the requirement to maintain operational safety without exceeding the design limitations of the boiler.