🔍 Key Concepts

• Thermal expansion of boilers and why sliding feet are used • How sliding surfaces should be kept so they can move freely • Which actions might prevent or hinder movement versus which help it

💭 Think About

• Ask yourself: what is the main purpose of boiler sliding feet, and what happens if they cannot move freely when the boiler heats and cools? • Look at each option and decide: does this action make the sliding surface smoother and freer to move, or does it increase friction or lock it in place? • Which maintenance task is normally used to keep any sliding metal‑to‑metal surface clean and free to move, especially in a hot, expanding structure?

✅ Before You Answer

• Verify which choice keeps the sliding contact surfaces clean and free-moving, not locked in place • Check whether adding a coating or torque would interfere with sliding action • Confirm which option is a common practice for maintaining moving/sliding metal surfaces on machinery foundations