The Locomotive - Lighthouse Survival Blog

PUBLISHED BY THE HARTFORD STEAM BOILER INSPECTION AND INSURtNCE COMPANY.
:Ne%v Series—Vol. XIV. HARTFORD, CONN., MAY, 1893. No.
Concerning* Domes.
As a general rule, we believe domes to be unnecessary ; for experience has shown us
that if a boiler is properly designed and properly set, dry steam may be had without
them. However, many of our patrons prefer to have their boilers furni.shed with domes,
and there is really no objection to them, provided they are made and put on correctly.
The most striking source of weakness in a .steam dome is the hole that is cut out of
the shell to allow the entrance of steam, this hole being often made the full diameter of
the dome. Sometimes, however, it is made, say, only seven inches in diameter; and
Fig. 1. — A C'oRKECTLY Designed Dome.
sometimes, too, a number of small holes, three-quarters of an inch or so in diameter, are
drilled through the .shell in the place of one large one. Each of these methods is liable
to objections, which we proceed to consider.
There can be no doubt that a large opening in a boiler shell is an element of weak-
ness, for, although we may re-enforce the periphery of such a hole, and stiffen it as