A discharge pipe used on a safety valve should be what size compared to the safety valve?

The correct answer, which states that a discharge pipe used on a safety valve should be no less than the same size as the safety valve, is based on safety and efficiency considerations.

When a safety valve opens, it is designed to relieve excess pressure from a boiler or pressure vessel rapidly. If the discharge pipe is smaller than the valve outlet, it could create a restriction that leads to back pressure on the valve. This condition might prevent the valve from closing properly or functioning as intended during an overpressure situation. A pipe that is the same size as the safety valve ensures that the steam or gas can flow freely and quickly vented away from the system, thus reducing the risk of potential accidents or malfunctions.

Ensuring that the discharge pipe is adequately sized helps maintain the safety mechanisms of the boiler system, ensuring pressure relief is quick and effective. Avoiding under-sizing minimizes the risks of dangerous delays in pressure relief during critical operations.