🔍 Key Concepts

• Boiler safety valves purpose and how they limit maximum pressure • Relationship between set pressure, working pressure, and relieving capacity • Effect of increasing vs. decreasing boiler working pressure on whether existing valves can still pass enough steam

💭 Think About

• If the boiler operates at a higher pressure than before, what happens to steam generation rate and the amount of steam the valves must discharge? • If the boiler operates at a lower pressure than before, does that make it harder or easier for the existing safety valves to protect the boiler? Why? • Think about which condition (higher or lower working pressure) is more likely to demand a greater relieving capacity from the safety valves.

✅ Before You Answer

• Verify how relieving capacity is defined: is it about how much steam (mass/time) a valve can discharge at a given pressure? • Check whether operating at a lower pressure than the valve’s original design would normally reduce or increase the steam flow demand on the valves. • Confirm which change in pressure would make the existing valves potentially too small to keep pressure from rising above safe limits.