Portions of the Marine Boiler which Become Thin by Wear.
These are generally situated, 1st, at or a little above the line of fire bars in the furnace; 2d, the ash pits; 3d, combustion chamber backs; 4th, shell at water line; 5th, front and bottom of boiler.
The thinning can usually be detected by examination, sounding with a round nosed hammer, or drilling small holes in suspected parts not otherwise accessible for examination.