New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1875-01-22
sTEAM-BOILER EXPLOSIONS.
AN ADDRESS by JAMES A. WHITNEY.


The New-York Society Of Practical Engineering
met last evening in the Geographical Rooms Cooper
Institute The President. James A. Whitney, deliv-
cred an address on the subject of Steam Boiler Ex
plosions."
Tho explosion OF steam generator he said, is not On
occult or mysterious occurrence but is due to the
operations OF natural laws and tho manifestation OF
natural forces Honce II attendant circumstances are
thoroughly investigated and deductions drawn with the
same regard for logic and common sense that are cxer
cised the Investigation OF other phenomena, tho true
cause OF an explosion. In any given CASE may be cor
recty indicated inc times out Of en There only one
reason why boiler expodes and that IS that the pres
sure Of steam within Is greater than the resisting
strength OF the boiler This preponderance OF pressure
may result from many causes and hence the confusion
that exists In tho popular mind. Its effects may even
yary according to the slowness or rapidy with which
the excessive pressure brought about and this adds
TO the compexity OF the question In instances
because conditions apparently the same seem to induce
different results. There are only three safeguards
against poson-the strong and proper construction
OF boilers at outset the testing OF them far beyond
the present rdio OF test to working pressure and the
employment Of qualified ongne-dri III these con-
dt,ons should DO imposed upon owners and users OF
steam power either by the pressure OF public opinion or
by legislation and nractions met with Inevitable pun
ishmont steam boiler explosions would become as rare
as tho falling OF substantial buildings.
Safety and tho production of largo quantity Of dry
steam are the essentials OF good boiler but these
two requirements antlgontc to each Others tho
best boilers are the result OF compromise III we could
have perfect hollow sphere OF metal would have tho
orecay the strongest form OF steam general and In
infancy OF steam engineering some spherical boilers
we're made IN gland aud even continued IN use nearly
IN orr own time But Ia possible to bring the fire
tact with only small portion OF tho surface and hence
we have little steam for great al Of fuel Tao form,
| With ha nnhar
meath and playing upward against tao sides Tnls
greater heating surface but the ends do not bear
the same relation pressure the sides, and must
be stayed by braces that shift portion OF the strain on
the heads to other portions Of the she'll II, now our
fire ia started under tho boiler. tho lower part heats
faster than tho upper part, and consequently expands
more This bends the lower outward on the arc OF
circle which although impercepbe to the eye. is the
irresistible force. Tlis expansion OF tho
lower part the boiler brings strain ppon the upper
part when the boiler ia allowed N cool 1t resumes its
original form. Al each change Of temperature there
fore, there Is to and fro movement OF the
Tapped edges of the plates where they are riyeted
| together. The final effect is that the plate cracks
aloug tie line OF its least resistance. In
some boilers the fracture may be along line OF
rivets and entirely hidden from possible view.
But II the veting be extremely good the minute bend
ing and fro Ia apt to occur In plate close to
overlapping edge OF the plate to which IL Is rveted,
and when the crevce opens to the interior Of the boiler
any acid In the water will chemically to increase it.
This is termed growing" BY the English engineers,
and not confined TO any particular type. For II, n-
stead OF placing fires beneath the cylinder, ex
tend large cylindrical 1Ie through the cylinder or
she'll OF the boiler, NO simply change the locality IN
which the effects OF this alternate expansion and CON
traction are exerted The lcs fixed in tho ends Of
the shell, and hotter than the shell,
and OF course expand B,ng
Aned against tho ends. tAe 1jes bend upward
II we put a steam drum which Tho otherwise waste
neat from the escaping products VI combustion may dry
the steam from it3 contained ycsiccs Of vIpOr
c0mplish increased economy OF fuel but by adding
vertical cylinder intersecting horizontal one. have
additional joint between portions subject TO quite
different temperatures, and at which "grooying" Is
liable to occCr. IL the joint Is made with angle iron
In which the grain parallel with the sharp corner
in angle OF the iron, the danger Is much Increased
and this has led American engineers 70 discard the En-
glsh plan Of using angle iron in steam boilers The new
and system ia make the Joint a having
radius about four inches Tao ends OF the shells
cylinders OF boilers often fitted in their places with
angle but the same objection holds as In the filling
of the dOmes As rule. sharp and rigid corners should
be avoided between plates liable to unequal expansion
from heat Tnis gradual deterioration OF boilers from
the cause indicated is Of the most nsdlous Of all
the causes OF explosions and 1t that il inherent
in all notifications of the cylinder type sk and good
may reduce the danger but cannot wholly OBJ
vste it.
The Westhald boiler was a common return dus boiler.
but with q very large heating surface, having about
dozen hues in ALL and evidently capable or nerating
steam as rapidly as any example OF IT'S effective class
"a feet and 10 feet in diameter, furnished at
the front with the superheang device TO which have
referred, the lower part OF the smoke stack passing
through steam-drum The ends were stayed by
oDllque staySds running to the central part OK the
the inner ends OF the two series OF STAYS The
three parts II was clear case OF oyerpressure Tne
shell burst because 1t was too weak 10 resist the strain
brought upon II by the steam within. II -,
therefore, NO marvel that the boiler exploded, and the
next question: shufod and eyaded has been TO this
day. IL simply TO where to fix the blame. First and
foremost 1t rested upon those whose duty t was 10 keep
the boiler fully up 70 the SHABBY requirements Of our
TdicuOusly lenicnt law OF Inspection but than
all u the carelessness OF public opinion which
permits boilers to be run on tho strength OF tests wholly
condemned as 10 efficiency, by tina best engineering
experience OF tho age. At the time OF the Wesheld
disaster there running the + ts River, the
various Brooklyn ferries nineteen ferryb sixteen
of these were subjected TO hydrostac pressure OF
40 mounds tn the 40 Ire inch and were permitted work
ne pressure ~ pounds although OF them were
eight, nne and ten years old One was tested at IS
pounds and allowed a working pressure Of o. but
Two new boilers tested ~ ana worked ~ 3d.
Two Jersey City boats we're tested at 40 pounds aud
worked at Is. Twenty--Ix towing vessels had
age boiler test OF lOt pounds per square inch and
working pressure OF These proportions that al
though leaving too narrow margin to be accepted by
sound Judgment, give greater safety than the practice
erfybOats. strong boiler, proved to he so by ade
quste testing is tho only sure reliance ana all other
means OF precluon auch as safeyyaves. involve dan
ger from the fact OF leading TO false security.
But even the poor provision OF double was
lackiog from tne majority OF fourteen PASSENGER
steamers plying from New-YorS HarbOr T9e
average hydrostato pressure was s. pounds TO
the square inca, and the average working
pressure pounds. or six freight steamers was
tested % pounds and allowed To carry a. The
test AZ; the working pressure permitted 80
pounds per square incn With IA single exception these
had Que safety valve apiece. The hydrOsto test Of
the Westheld "a pounds its WORKING pressure u.s.
The last pressure known TO have been shown By the
gauge stated at AZ pounds and, shall see the
proportions OF heating surface sufficient 10 send
tine pressure far beyond this in less minute 1t
will be that the ratio OF test to working steam
pressure boiler OF the Westted Gid dlffsr
teriay from that with all boats OF class aud
do not know that any change has DecL the
law or practice this head. Ia estimating the utility
of am let lis them IN