What is the allowable pressure rise in the steam drum when the PSV is active?

The allowable pressure rise in the steam drum when the Pressure Safety Valve (PSV) is active is typically set to a maximum of 3%. This is in accordance with safety and operational standards that govern pressure vessels, where the PSV is designed to protect the system by opening to relieve excess pressure.

When a PSV activates, it is essential to limit the pressure increase to prevent potential damage or unsafe conditions within the steam drum. A 3% rise is considered a safe threshold that allows for operational flexibility while ensuring that the vessel remains within safe limits. This allowance takes into account the normal operational fluctuations and the quick response of the PSV to stabilize pressure within the drum.

Understanding this percentage helps in assessing whether steam systems are functioning correctly and assists in maintenance and operational planning. Knowledge of the allowable pressure rise is crucial for steamfitters and professionals working with pressure vessels to ensure compliance with safety regulations and to maintain system integrity.