Steel rivets should be heated in the hearth of a reverberatory furnace
so arranged that the flame shall play over the top of the rivets, and
should be heated uniformly throughout the entire length of the rivet
to a cherry red. Particular attention must be given to the thickness
of the fire in which they are heated.
Steel, of whatever kind, should never be heated in a thin fire,
especially in one having a forced blast, such as an ordinary
blacksmith's or iron rivet furnace fire. The reason for this is that
more air passes through the fire than is needed for combustion, and in
consequence there is a considerable quantity of free oxygen in the
fire which will oxidize the steel, or in other words, burn it. If free
oxygen is excluded steel cannot burn; if the temperature is high
enough it can be melted and will run down through the fire, but
burning is impossible in a thick fire with a moderate draught.
This is an important matter in using steel rivets and should not be
overlooked; the same principle applies to the heating of steel plates
for flanging.
_Riveting._--There are four descriptions of riveting, namely:
(1) Hammered or hand riveting.
(2) Snapped or set.
(3) Countersunk.
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