The soot and ashes collect on _the exterior_ of the tubes in this form
of boilers, instead of inside the tubes, as in the tubular, and they
must be as carefully removed in one case as in the other; this can be
done by the use of blowing pipe and hose through openings left in the
brick work; in using bituminous coal the soot should be brushed off
when steam is down.
All the inside and outside surfaces should be kept clean to avoid waste
of fuel; to aid in this service the best forms are provided with extra
facilities for cleaning. For inspection, remove the hand holes at both
ends of the tubes, and by holding a lamp at one end and looking in at
the other the condition of the surface can be freely seen. Push the
scraper through the tube to remove sediment, or if the scale is hard,
use the chipping scraper made for that purpose.
Hand holes should be frequently removed and surfaces examined,
particularly in case of a new boiler. In replacing hand hole caps,
clean the surfaces without scratching or bruising, smear with oil and
screw up tight.
The mud drum should be periodically examined and the sediment removed;
blow-off cocks and check valves should be examined each time the boiler
is cleaned; when surface blow-cocks are used they should be often
opened for a few minutes at a time; be sure that all openings for air
to boiler or flues _except through the fire_, are carefully stopped.
If a boiler is not required for some time, empty and dry it thoroughly.
If this is impracticable, fill it quite full of water and put in a
quantity of washing soda; and external parts exposed to dampness should
receive a coating of linseed oil. Avoid all dampness in seatings or
coverings and see that no water comes in contact with the boiler from
any cause.
Although this form of boiler is not liable to destructive explosion,
the same care should be exercised to avoid possible damage to boilers
and expensive delays.