Which safety valve relieves first in a steam system?

In a steam system, the superheater relief valve is designed to operate first because it is strategically positioned to protect the superheater, which is particularly vulnerable to overpressure conditions. The superheater increases the temperature of steam above its saturation point, which requires careful monitoring and control of pressure.

The superheater relief valve is calibrated to relieve pressure before it reaches potentially damaging levels, ensuring that the superheated steam does not exceed safe operational limits. This is crucial because superheating can lead to excessive thermal stress on the system components, which might result in failures if not mitigated early through proper relief mechanisms.

In contrast, the other options may serve important roles in steam system safety but do not prioritize the superheater as the first point of relief in overpressure situations. For example, while the boiler relief valve and pressure relief valve are also critical for safety, they may operate under different pressure thresholds and are not specifically focused on the superheater’s immediate protection. The safety valve on steam lines may also activate under different circumstances but is not designated to relieve pressure ahead of the superheater relief valve.