The Northern Daily Times.
Liverpool, Merseyside, England, 1853-11-14 00:00:00

THE BLACKBURN BOILER EXPLOSION.
ADJOURNED INQUEST.

IMPORTANT REPORT BY MR. FALRBAIRN, C.E.

FROM OUR OWN REPORTER.)
BLACKBURN, Saturday Night.

Most important evidence was adduced to-day, relative to
the over-working of the boiler, which exploded on the 2nd
instant, at Mr. Hesketh's weaving-shed, Starkie-street, in
this town. Mr. Hargreaves, the coroner, resumed the in-
quiry in the Court House at ten o'clock this morning. Mr.
Backhouse again appeared for the proprietor of the mill, and
Mr. Clough for the owners of the adjacent property. Great
interest was excited by the proceedings.

Mr. Fairbairn, of Manchester,- was examined at great
length. His evidence is embodied in the annexed report :
I visited this town on Wednesday last, for the purpose of
examining into the cause of a boiler explosion which took
place at the Eagle Mill, Starkie-street, on the 2nd inst.
On my arrival found the whole of the engine-house,
cotton-mill, and weaving-shed, a heap of ruins, and the ex-
ploded boiler lying in the middle of the yard, where it had
been removed from a dwelling-house, into which it had been
projected by the elastic force of the steam—a distance of 80
yards from its seat.
In its progress it had not only blown up a portion of the
factory under which it was placed ; which was two storeys
high, but it destroyed the whole of the weaving-shed—
cleared in itspassage the greater portion of a dwelling house,
and finally lodged itself, as stated above, in the interior of a
house on the opposite side of the street.
In this position it remained until removed by orders from
the jury.
In tracing the causes of this accident I am relieved from
anything approaching to uncertainty, by the fact that the
boiler was totally inadequate to the work it had to per-
form.

First. It was 16 feet long, 6 feet 6 inches deep, 5 feet 2
inches wide, and composed of plates tths of an inch thick
on the sides and top, and inch thick over part of the
bottom.

Secondly. It was old, of the waggon shape, and the worst
_possible form to sustain severe pressure.
Thirdly. It was improperly and injudiciously stayed,
reposing large flat surface to internal pressure.
Fourthly. It had an exceedingly defective safety valve,
and generally, it was totally unsuited in strength and form
to work a non-condensing and high pressure steam engine.
With the permission of the jury, I will explain the
reasons why I consider this boiler should never have been
used for such a purpose, with so high a working pressure as
35 lbs. on the square inch.
This is probably the lowest pressure that a non-condensing
engine can be worked at with anything. like effect, certainly
not with economy, and although it is stated that one of
Smith's indicators was attached to the boiler; these are not
to be depended upon, unless kept clean and frequently ad-
justed by the best of all tests, a mercurial guage-35 lbs.
might be the guage pressure—but it is more than probable,
from the reason assigned, that the pressure at which the
boiler was worked, was 40 lbs or upwards. Ido not mean
to assert that this was positively the case, but I think I shall
be able to show that with all its defects, the boiler did not
burst with less than 45 or 50 lbs. pressure on the square
inch.

The weakest parts of this boiler were the flat ends, only
kths thick, which contained an area of nearly 28 square
feet, and their only support was a single longitudinal stay in
the middle. Now this stay, which was of wrought iron 11
inches square, had to sustain a tensile strain at a working
pressure of 35 lbs. to the inch, of 2641 tons, minus the stiff-
ness or resistance of the plates, for which I have allowed
41 tons. On this computation we have 26.5 tons--4.5 tons
—22 tons, as the actual strain upon the longitudinal stay.
Now our best bar-iron will sustain a force of 22 to 24 tons
to the square inch ; and as this stay—which is none of the
best—had to sustain a pressure of 11 tons, it was beyond
the point of elongation, but within the limits of its ultimate
strength.
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The other parts of the boiler, such as the sides, are equally
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better calculated to resist internal pressure.
There were eight transverse stays in the length of the
boiler, four immediately above the crown or curved part of
the bottom, and four more above; a littlebelow the diameter
of the arched top. These stays, as well as the longitudinal
ones, were rivetted to the sides and ends of the boiler by
plates bent in the form of a trough, and the stays were fixed
into them with cotters in the usual way.
On each of the sides the pressure may be taken at 204
tons, and assuming the stays to be equally divided, they
would have to sustain a tensile strain in the ratio of the area
of the spans into which they were respectively divided; but
as these spans were unequal the result would be a variable
strain upon each. Again, the upper stays which formed the
chord line of the circular top would be subjected to con-
siderably more strain than the bottom ones, and having also
to sustain the curved plates along the bottom by the diagonal
stays, it is evident that a variable strain of not less than 18
to 20 tons must have been acting upon them, or about 10
tons to the square inch, leaving only one ton per square inch
under the force to which the longitudinal stay was subjected,
iu resisting the preaeure upon the thto.
If we take this part of the construction with all its de-
fects, and want of proportion, it will be found to contain
little or no greater powers of resistance than the flat ends,
which had only one stay ; and this fact leaves the question
as to which of the stays was the first to yield as matter of
doubt.

This, however, is of no great moment, as the results would
have been the same in either case, namely the rupture of the
boiler by tearing the sides from the ends next the engine,
and hence followed the destruction which ensued. This ap-
pears to be the case, as a considerable portion of the boiler
had approached the cylindrical form, the natural result of
an equable and uniform force from within.
With things in this state, with the force applied on the one
hand, and the powers of resistance on the other in direct an-
tagonism (if I may use the expression), it appears that the lives
of every one employed in the walls, or within reach
of the influence of this explosive vessel, were, and,
had been for years, suspended by a thread, which
the least change of pressure might in a moment cut
asunder. That moment arrived on the morning of the
2nd inst., and fortunate it was that the catastrophe
occurred at a time when the people were at breakfast, or a
greatly increased number of sufferers might have been
added to the list.

Looking at the ruins, and the position in which the
boiler was found after the explosion, I am of opinion that
the end next the steam-engine was the first to give way ;
that an active fire was under the boiler when the engine
was standing, and the only escape for the steam was through
a valve 1e inches diameter. Now this valve was totally
insufficient to relieve the boiler from the rapidly increasing
pressure which, for some time previous to rupture, had been
taking place in the boiler.
That pressure, it is now well known, from some carefully
conducted experiments recently made, progresses in a fear-
fully accelerated ratio ; and we cannot be too careful, under
such circumstances, in ascertaining with certainty that the
safety valves are not only efficient, but at least of nearly
double capacity to the generative powers of the boiler, and
in good working condition. Unfortunately, such indis-
pensable precautions had never been attended to in this
instance, and the result was, the rupture of the far end of
the boiler, which was torn from the sides and bottom ; and
the steam acting. with a force equivalent to the pent-up
pressure, forced it from its seat with the velocity of a
projectile, and cleared walls, roofs, and everything before
it. The end was thus carried in the direction of the steam-
engine and chimney ; it was forced clean through the
engine-house, and ultimately landed in a candle-maker's
yard, on the opposite side of the building.
The boiler itself and the other flat end—also torn from
the sides and bottom—were projected in the opposite direc-
tion, and ultimately landed, after clearing all obstructions
before them in the very centre of a dwelling-huuse on the
opposite side of the street.
In these explosions the direction of motion, it will be
observed, is governed by a line passing through the centre
of rupture, and the centre of pressure, and in this case the
line of the forces appear to have been nearly horizontal, and
at the same time as nearly as possible in the centre of
gravity. Hence the line' of projection ; which was almost
parallel with that of the boiler itself.
It would have been a relief to my feelings. if I could have
closed this statement without further remark ; but a sense
of duty compels me to censure in the severest terms, not
only the original construction of this boiler, but the uses to
which so imperfect a construction was applied ; and I hope
may warn the responsible parties in analagous cases which
I fear exist, and wherein the lives of the public are in emi-
nent jeopardy. It is absolutely indispensable that a careful
inspection should at once be made, either by these parties
themselves or by some experienced person fully qualified
for such a task.

In the performance of the assigned duty, I believe I can-
not do better in conclusion than repeat the precautions and
suggestions which I endeavoured to enforce upon the atten-
tion of the owners of steam boilers on the occasion of a
similar and equally fatal occurrence, at Riga-street Man-
chester.

The suggestions are as follsws :
Ist. Boilers should not on any account be placed under
buildings where people are employed,
2nd. Every boiler should be constructed of sufficient
strength to resist not less than five or six times its working
pressure ; and every boiler should be proved by hydraulic
presses to double its intended working pressure.
3rd. Every boiler should have two safety valves, collec-
tively equal to one and a half times the area of the steam-
pipe, on the computed generative power of the boiler ; one
of these valves to be under lock and key, and so arranged as
to render it impossible to increase or diminish the load.

4th. The-proprietor or some authorised person to inspect
the state of the boiler and valves once a month, every time
the boiler is cleaned, and to record the same in a book kept
for that purpose. For the last sixty years this has been the
custom in Cornwall, where steam of high elastic force is in
general use. All the engines and boilers of that district are
under the control and supervision of competent persons.
Monthly returns are given of the duty performed by each
engine, the quantity of fuel consumed. and by constant care
and attention to the state of the boilers and machinery, a