Apparently, a joint constantly immersed in water on one side cannot rise
in temperature above the boiling-point of the liquid, even when its other
side is heated strongly; but since, even if a generator is not charged
with naturally hard water, its fluid contents soon become "hard" by
dissolution of lime, there is always a liability to the deposition of
water scale over the joint. Such water scale is a very bad heat
conductor, as is seen in steam boilers, so that a seam coated with an
exceedingly thin layer of scale, and heated sharply on one side, will
rise above the boiling-point of water even if the liquid on its opposite
side is ice-cold. For a while the film of scale may be quite water-tight,
but after it has been heated by contact with the hot metal several times
it becomes brittle and cracks without warning. But there is a more
important reason for avoiding the use of plumbers' solder. It might seem
that as the natural hard, protective skin of the metal is liable to be
injured or removed by the bending or by the drilling or punching which
precedes the insertion of the rivets or studs, an application of soft
solder to such a joint should be advantageous.
Pages:
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128