The Locomotive - Lighthouse Survival Blog

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PUBLISHED BY THE HARTFORD STEAM BOILER INSPECTION AND INSURANCE COMPANY.
New Sekies—Vol. XIV. IIAIiTFORD. CONN., AUGUST, 1893. No. 8.
Iron Smoke Stacks.
As a general rule, l^rirk chiiniK'y.s arc greatly to be pre-
ferred to iron stacks, but there are many cases in which they
cannot be used, or in which their u.se would involve prohib-
itive expense. Thus the nature of the soil may be such that
a proper foundation for a brick chimney cannot be had v/ith-
ont an enormous outlay of money. Again, a chimney of
some kind may be wanted for temporary u.se only, to provide
additional draft pending the construction of a new chimney,
or for some other purpose. In these cases iron stacks are
often useful, both on account of their cheapness, and because
they can frequently be bought in the market, ready made.
They are often used in iron works, too, where they can 1 e
readily and cheaply made. They are considered, by some, to
be more efficient than brick chimneys of the same propor-
tions, because they do not allow cold air to leak into the flue
and chill the heated gases. This action is often perceptible
in brick chimneys that have stood for some years, but it is
doubtful if the advantage of the iron stack in this particular
is sufiicient to more than counterbalance the increased radia-
tion of heat which takes place from the comparatively thin
plates of which the iron stack is composed. The effect of the
weather and of the products of combustion on iron stacks is
often very marked, and we have known of cases in which
holes were corroded through these stacks so rapidly that the
entire stack had to be replaced every year. Of course this is
an extreme case, but the same action goes on more slowly in
many other cases. To lessen the corrosive effects of the
weather, iron stacks should be kept well painted. Many
recipes for making paints suitable for this purpose have been
published, but it will not be necessary to discuss them in the
present article as the paints themselves can be bought, ready
for use. Iron stacks are also sometimes lined with brick, to
protect them from the action of the hot products of combus-
tion, and add to their stability. Iron stacks are usually held
in position by four wrought iron guy rods, secured to a ring
of angle iron that is riveted to the stack about two-thirds of
the way up, and anchored at a distance from the base of the
stack about equal to the height of the ring of angle iron P^IG. 1.