General Engineering Flashcards

What is the purpose of a 'coffin plate' in a marine boiler?

Answer: A reinforcing plate used at the junction of the furnace and boiler shell

A coffin plate (also called a gusset stay) reinforces the structural junction between the furnace and the boiler shell to resist pressure-induced stress.

Which condition would cause a centrifugal pump to cavitate?

Answer: Suction pressure falling below the vapor pressure of the liquid

Cavitation occurs when suction pressure drops below the liquid's vapor pressure, causing vapor bubbles to form and then collapse violently, damaging the pump impeller.

What is the correct action if the 15 ppm bilge alarm activates while overboard discharge is underway?

Answer: Immediately stop the overboard discharge and divert to a holding tank

MARPOL requires immediate cessation of discharge when oil content exceeds 15 ppm; the oily water must be diverted to a slop or holding tank.

What is the purpose of a 'stuffing box' (packing gland) on a centrifugal pump?

Answer: To prevent leakage along the pump shaft where it exits the casing

A stuffing box contains packing material compressed around the pump shaft to minimize fluid leakage where the rotating shaft passes through the stationary pump casing.

In marine electrical systems, what does a 'dead front' switchboard mean?

Answer: A switchboard where all live parts are enclosed and inaccessible from the front

A dead front switchboard has all energized conductors and bus bars enclosed behind the front panel, reducing the risk of accidental contact by personnel.

What is the function of a governor on a marine diesel engine?

Answer: To automatically regulate engine speed under varying load conditions

A governor automatically adjusts fuel delivery to maintain a set engine speed regardless of changes in load, preventing overspeed or underspeed conditions.

What is 'hydraulic lock' in a diesel engine, and why is it dangerous?

Answer: Liquid in the cylinder that cannot be compressed, potentially bending the connecting rod

Hydraulic lock occurs when liquid (water or oil) accumulates in a cylinder; since liquids are incompressible, attempting to start the engine can bend or break the connecting rod.