ASKED OF A CANDIDATE FOR A MARINE LICENSE RELATING TO DEFECTS IN BOILER
WITH ANSWERS.
If you find a thin plate, what would you do?
Put a patch on.
Would you put it on inside or outside?
Inside.
Why so?
Because the action that has weakened the plate will then act on
the patch, and when this is worn it can be replaced; but the plate
remains as we found it.
If the patch were put on the outside, the action would still be on
the plate, which would in time be worn through, then the pressure of
the steam would force the water between the plate and the patch, and
so corrode it; and during a jerk or extra pressure, the patch might
be blown off.
It is on the same principle that mud-hole doors are on the inside.
If you found several thin places, what would you do?
Patch each, and reduce the pressure.
If you found a blistered plate?
Put a patch on the fire side.
If you found a plate at the bottom buckled?
Put a stay through the centre of the buckle.
If you found several?
Stay each, and reduce the pressure.
The crown of the furnace down?
Put a stay through the middle, and a dog across the top.
If a length of the crown were down, put a series of stays and dogs.
A cracked plate?
Drill a hole at each end of the crack; caulk the crack, or put a
patch over it.
If the water in the boiler is suffered to get too low, what may be
the consequence?
Burn the top of the combustion chamber and the tubes; perhaps
cause an explosion.
If suffered to get too high?
Cause priming; perhaps cause the breaking of the cylinder covers.