Exam Question

Auxiliary boiler safety valves are critical components for the safe operation of a boiler, preventing over-pressurization and potential catastrophic failure. Their design, maintenance, and operational checks are subject to stringent regulatory requirements.
**(a) Clearances needing checking when lapping valves to seats (5 Marks)**
When lapping safety valves to their seats, several critical clearances must be meticulously checked to ensure proper operation, correct lifting pressure, adequate discharge capacity, and controlled blowdown. Lapping is a precise process to achieve a perfect, gas-tight seal between the valve disc and seat.
* **Valve Lift (Nozzle Lift / Disc Lift):**