Evening star., 1902-02-21
WHY BOILERS EXPLODE.
An Old Engineer Gives the Result OF
His Experience.

s.Why do boilers burst?" repeated an old
engineer of whom the question was asked.
We'll, boilers are like people, in that when
they are ill-treated they get red-hot ana
explode.
THE principal cause Of explosions is be-
cause OF insufficient water in the boiler.
The water must be kept above the tubes
so that it may boil freely. When 1t fails
below the tubes the boiler becomes fed-hot,
the steel plates soften. expand and crack,
and, swish, up she goes, ana All else III the
immediate vicinity. -
The number OF boiler explosions In diff
Serent parts OF the country lately Calls 10
mind the constant menace 10 human lie
and property existing literally under our
very feet. as 1t Is In Easements and under
the sidewalks. where most or the poHers
are situated. The great wonder is tnat
more do not go up In the ar, lhcldentally
carving the building and Its contents or
the sidewalk with them. ! saw the wreck
age caused by the fatal boiler explosion In
Pittsburg recently. The building was COM
pletely demolished. and the ruins looked as
though the buildings had been blown 10
pieces and the ground lereled by dynamite.
"Bo,lers also burst where they have flaws
and unseen defects in the metal which VIII
not stand the strain OF the pressure OF the
steam, and the plates part at this partic-
Hlar spot Inspections often fall TO reveal
these flaws, with terrible results. Cold
water let into the boiler when 1t is hot and
when there IL no water OF llSuTlClent wafer
inside often means an explosion. The steam
Is generated 30 rapidly, and Its force Is SO
terrific, that the plates part like pieces or
paper. In the iron region the sulphur In
the water used has eaten the bolts of boil
ers have attended inside OF three months,
and great care as to their repair In season
had to be exercised. Scales will also form
on the tubes, and when thickened so that
the steel becomes red hot at this point, but
the water cannot get to the metal because
of the scale these 'blisterS' part and an eX-
plosion results.
I'm some Of the big department buildings
IN Washington the boilers are fired to only
about one-sixth Of their tensile strength, and
boilers with licensed capacity of with
standing 100 pounds of steam pressure to
the square inch carry only from ninety to
100 pounds, the safety valves being set at
the latter figure. When the safety valves
work all right a vent for the danger pres
sure Is permitted, but when they don't. as
Is sometimes the case-well. you will learn
all about 1t when you wake up the next
minute in the other world.
Boilers are better made now than for
merly. and are constructed Of steel instead
Of iron. as long ago. The boiler steel Is
tested to Withstand a tensile strain Of
10000 pounds to the square inch as against
10000 pounds Of q generation ago. Boiler
explosions. while frequent enough now, do
not compare in number as at that period.
There il q moro perfect system of inspec-
tion and q better class Of men In charge,
who are required to pass an examination
and receive licenses before they are allowed
to run stationary engines. as my remarks
do not apply to the boilers of locomotives"