Is it permissible for a boiler to have a feed water sourced from the water main at a pressure of 6% greater than the release pressure of the highest safety valve?

In hydronic and process piping systems, it is crucial to maintain safe operating conditions to prevent overpressure situations. When considering the feed water pressure sourced from the water main, it is essential to ensure that this pressure does not exceed the release pressure of the boiler's safety valves.

The statement that it is permissible for a boiler to have a feed water pressure 6% greater than the release pressure of the highest safety valve aligns with established industry practices. Safety valves are designed to relieve excess pressure and protect the boiler from over-pressurization. If the feed water pressure is above this threshold, it may cause the safety valve to remain closed even when there is a pressure increase, potentially resulting in unsafe operating conditions.

Therefore, it is permissible because having a feed water pressure that is slightly above the release pressure of the safety valves can help maintain a proper operating condition, assuming that the system is properly designed and monitored. This is particularly applicable in systems where the boiler operates under controlled conditions and is regularly inspected for safety and functionality.