Class 5 Boiler Practice Exam

In low pressure steam boilers, the valve needs to be at least equal to the MAWP of the boiler, but no less than what pressure?

1. 20 psi

2. 30 psi

3. 40 psi

4. 50 psi

The correct answer is: 30 psi

In low pressure steam boilers, the pressure relief valve must be designed to handle the maximum allowable working pressure (MAWP) of the boiler. However, to ensure the safety and functional reliability of the system, there is a minimum pressure requirement stipulated for these valves. This is because pressure relief valves need to be able to accommodate potential operational fluctuations without failure, and if a valve’s setting is too low, it may not provide adequate protection or could lead to premature activation, disrupting operations. In this context, the correct answer, which indicates that the minimum pressure setting for the relief valve should be no less than 30 psi, aligns with industry standards. This threshold is established to ensure that the valve remains within a safe operational range, providing effective pressure control and preventing any potential safety hazards that might arise if the valve is set below this level. This specification helps to ensure the integrity of the pressure relief system and enhances operational safety in low pressure steam applications.