What should be the required safety valve pressure settings on an existing boiler?

The required safety valve pressure settings on an existing boiler must adhere to safety and operational standards to ensure proper functioning and to prevent hazards. The correct approach involves having one safety valve set at or below the Maximum Allowable Working Pressure (MAWP) while others can be set within a 3% margin above the MAWP. This configuration is crucial because it allows for a primary safety mechanism that ensures the boiler does not exceed its safe operating pressure.

By keeping one valve strictly at or below the MAWP, you ensure that there is a guaranteed release point for excess pressure, which is vital for protecting the system from overpressure situations. The additional valves set just above the MAWP can serve as backup safety measures without compromising the safety of the boiler. This layered approach adds a level of redundancy while remaining compliant with safety regulations, thereby safeguarding both equipment and personnel.

In contrast, setting all valves at or below the MAWP may not provide adequate fail-safes in all situations, and setting valves 5% above the MAWP poses unnecessary risks of allowing the pressure to exceed safe levels. Having one or more valves set below the MAWP does not provide sufficient protection since it could result in unsafe operating conditions if all safety measures are not optimized. Thus