🔍 Key Concepts

• Flow path of steam in a "D" type marine boiler (from steam drum through superheater/desuperheater to the main steam line) • Purpose of the main steam stop valve in the steam system • Relative positions of superheater and desuperheater in a typical marine boiler steam circuit

💭 Think About

• Trace the path of steam starting at the steam drum: does it go to the superheater first or the desuperheater first? • Ask yourself: Where do we want to be able to shut off ALL steam going to the main engine/turbine — before it is superheated, while it is being desuperheated, or after it has reached its final temperature/condition? • Consider which component (superheater or desuperheater) directly feeds the main steam line to the engine or turbine.

✅ Before You Answer

• Verify the order of components: steam drum → superheater → (desuperheater, if fitted) → main steam line • Confirm that the main steam stop valve is the last isolation point before steam goes to the plant/engine, not between internal boiler components • Make sure you know whether the main steam line normally takes steam that is superheated, desuperheated, or saturated in this boiler design