Reg. 390 b
Scale Oils, etc
|Upon entering a boiler, the Inspector shall
examine all surfaces of the exposed metal to observe the
action caused by the use of water, oil scale solvents,
or other substances which may have intentionally or unintentionally
gone in with the feed water. Any evidence of oil is dangerous
and immediate steps shall be taken to prevent any further
entrance of oil into the boiler. Oil or scale in the tubes
of water-tube boilers or on plates over the fire of any
boiler is particularly bad, often causing them to rupture.
Reg. 390 c
|A given amount of corrosion along or immediately
adjacent to a seam is more serious than a similar amount
of corrosion in the solid plate away from the seams. Grooving
along longitudinal seams is especially significant as
grooving or cracks are likely to occur when the material
is highly stressed. Severe corrosion is likely to occur
at points where the circulation of the water is poor and
such places should be examined most carefully for evidences
of corrosive action.
If the Inspector decides that a boiler in one or more
of its parts is no longer fit for the pressure approved
for it, he must without delay report his proposal for
reducing the pressure to the Chief Inspector and at the
same time submit his calculation for the wasted parts
for check and approval of pressure.
With regard to the pitting and wasting of shell plates,
the Inspector should bear in mind that shell plates may
become reduce in thickness to an appreciable extent and
still be stronger than longitudinal seams.
All flanging shall be thoroughly inspected and particularly
the flanges of circular end plates that are not stayed.
Internal grooving in the fillet of such heads and external
grooving in the outer surfaces of heads concave to pressure
is very common since there is slight movement in the heads
of this character which produces this kind of defect.
Some types of boilers have what is known as the OG or
reversed flange construction in some of their parts that
may be inaccessible to the eye, but the condition shall
be determined by the insertion of a mirror which at a
proper angle will reflect back to the eye the condition
of such a place, or any other feasible manner.