According to regulations, boilers operating at what pressure or more are required to have two bottom blowdown valves mounted on the same blowdown line?

Boilers operating at a pressure of 100 psi or more are mandated to have two bottom blowdown valves on the same blowdown line as a safety and operational precaution. This requirement is in place to ensure that, in the event that one valve becomes inoperative or if maintenance is required, the second valve can continue to function, allowing for effective blowdown of the boiler. This helps to maintain proper water quality and prevent the buildup of sediments and impurities within the boiler, which could lead to operational inefficiencies or even catastrophic failures.

At lower pressures, such as those below 100 psi, single bottom blowdown valves are typically considered sufficient to manage the blowdown procedure, as the risks associated with boiler failure are less significant. However, as pressure increases, the potential severity of an incident also rises, necessitating additional safety features like a second valve. Thus, the requirement for two valves at 100 psi ensures compliance with safety regulations and promotes the longevity and reliable operation of the boiler system.