At what boiler pressure is the sodium nitrite solution injected into the boiler before a dry lay-up?

Sodium nitrite is commonly used in boiler systems to prevent corrosion during dry lay-up periods. The practice of injecting sodium nitrite solution into the boiler is specifically carried out when the boiler pressure is at or below 100 psig. This pressure threshold is significant because at higher pressures, the solubility and effectiveness of sodium nitrite can be compromised, leading to potential corrosion issues during the lay-up period.

Injecting the solution at pressures higher than 100 psig may not only limit the efficiency of the sodium nitrite but could also pose safety risks and operational challenges. Additionally, maintaining this pressure ensures that the solution adequately disperses throughout the system, offering better protection against corrosion. Therefore, the specific pressure limit set at 100 psig or less helps ensure that the sodium nitrite solution functions effectively to safeguard the boiler while it is not in operation.