IMPROVEMENTS IN STEAM BOLLERS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1866

page_text: LETTERS PATENT to Thomas Baldwin, of Bury, in the County of Lan-
caster, Engineer, for the Invention of "IMPROVEMENTS IN STEAM BOLLERS,
AND IN APPARATUS CONNECTED THEREWITH."
Sealed the 8th March 1867, and dated the 11th September 1866.
PROVISIONAL SPECIFICATION left by the said Thomas Baldwin at the
Office of the Commissioners of Patents, with his Petition, on the 11th
September 1866.
I, THOMAS BALDWIN, of Bury, in the County of Lancaster, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN STEAM
BOILERS, AND IN APPARATUS CONNECTED THEREWITH," to be as follows:-
The ordinary safety valves of steam boilers when weighted at a given
pressure will allow the steam in the boiler to rise considerably above that
pressure before the aperture through which the steam issues can be sufficiently
opened to allow the steam to escape as quickly as it is generated, and the
diameter of these valves are considerable, or they require to be numerous in
order to get sufficient area of exit for the steam, and in many cases do not
when blowing off lift more than one-hundredth part of their diameter; hence
we get large valves, heavy weights, and strong springs to keep them down
when used for high pressures and very small apertures to allow the steam to
escave

page_text: My improvements in apparatus or safety valves for steam boilers are
intended to obviate the use of large valves, heavy weights, and strong springs,
and consists in making the surfaces of the valvo and its seat a curve varying
in breadth and curvature as may be required.
One form of the valve is an ordinary sphere or a portion thereof whose
radius is greater than the radius of the aperture which it has to cover, and
the breadth of the said valve and its seating which are to be in close contact,
or nearly so, is regulated by the difference of pressure that lifts the valve
and the pressure to which it is reduced by allowing the steam to escape into
the atmosphere.
When a small difference is required between the lifting pressure and tho
closing pressure the radius of the said sphere or the width of the valve facing
is made less than when that difference is greater, or it is accomplished by
preventing the outer part of the facing from touching the valve. The valve
is weighted directly on its top, or the weight is suspended inside the boiler, or
a lever and weight is used instead of direct weights when required. When
the valve rises from its seat the two surfaces which were previously in contact
and equally distant assunder, or nearly so, are now unequally distant, that is,
the distance of the surfaces assunder increases as the horizontal radius of of the
points that were in contact decreases, thereby causing the steam to act like a
wedge outwards and lift the valve considerably more than in the case of the
ordinary valves before named.
.
The object of my improvements is to also deliver a quantity of steam
through a small valve equivalent to that delivered through a large valve of
the common construction, and thereby save expense. In some cases my
improved valve, one square inch in area, will deliver as much steam from the
same boiler as the common valve of twelve times the area.
My improvements in steam boilers consists in a combination of single and
double rivetted joints, the object being to make a stronger boiler from the
same thickness of plates than can be made by the ordinary plan of construc-
tion. For this purpose I use double rivetted joints for the longitudinal joints
of the shells of steam boilers and single rivetted joints for those passing
around the circumference of the shell. This combination makes the boiler
nearly as strong as if the shell had no rivetted joints at all. The distance of
the rivets assunder are such that the plates between the rivet holes is just on
the point of being torn assunder when the rivets are just on the point of being
sheared accross, thereby giving the strongest form of joint.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Baldwin in the Great Seal Patent Office on the
9th March 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BALDWIN, of Bury, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of September, in the year of our Lord.
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, tho
said Thomas Baldwin, Her special licence that I, the said Thomas Baldwin, my
executors, administrators, and assigns, or such others as I; the said Thomas
Baldwin, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
STEAM BOILERS, AND IN APPARATUS CONNECTED THEREWITH," upon the condition
(amongst others) that I, the said Thomas Baldwin, my executors or admini>-
trators, by an instrument in writing under my, or their, or one of their.
hands and seals, should particularly describe and ascertain the nature of the.
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Offico within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Thomas Baldwin, do hereby declaro
the nature of my said Invention, and in what manner the same is to bo
performed, to be particularly described and ascertained in and by the fol
lowing statement and accompanying Drawings (that is to say):-
The ordinary safety valves of steam boilers when weighted at a given.
pressure will allow the steam in the boiler to rise considerabley above that
pressure before the aperture through which the steam issues can be sufficiently
opened to allow the steam to escape as quickly as it is generated, and the
diameter of these valves are considerable, or they require to bo numerous in
order to get sufficient area of exit for the steam, and in many cases do not
when blowing off lift more than one-hundredth part of their diameter; hence
we get large valves, heavy weights, and strong springs to keep them down
when used for high pressures, and very small apertures to allow the steam to
escape.

page_text: My improvements in apparatus or safety valves for steam boilers aro
intended to obviate the use of large valves, heavy weights, and strong springs,
and consists in making the surface of the valve and its seat a curve varying
in breadth and curvature as may be required.
One form of the valve is shown in Figs. 1 and 2, where Fig. 1 is a lever
valve and Fig. 2 what is generally called a dead weight valve. The valve a
is an ordinary sphere, or a portion thereof, whose radius is greater than the
radius of the aperture b which it has to cover, and the breadth of the said
valve and its seating c which are to be in close contact, or nearly so, is
regulated by the difference of pressure that lifts the valve and the pressure to
which it is reduced by allowing the steam to escape into the atmosphere.
When a small difference is required between the lifting pressure and the
closing pressure the radius of the said sphere a or the width of the valve
facing c is made less than when that difference is greater, or it is accomplished
by preventing the outer part of the facing on c from touching the valve a. The
valve is weighted directly on its top, or the weight w is suspended inside the
boiler, as shown by Fig. 1, a representing a section of the shell of the boiler,
and
branches fixed thereon, or a lever 2 and weight w, as shown in Fig. 2,
is used instead of direct weights when required. In both Figs. a guard is
shown at e, and its use is to keep the valve a nearly concentric with its seating
during the time the steam is blowing off from the boiler and to guide it when
it drops upon its seat, which is accomplished by the spindle or rod 9 passing
loosely through the said guard e. When the valve a rises from its seat c the
two surfaces which were previously in contact and equally distant asunder, or
nearly so, are now unequally distant, as seen in Fig. 3, where a is the valve
and a, a, a, a, various positions occupied in lifting from a to as, that is, the
distance of the surfaces asunder increases as the horizontal radius of the points
that were in contact decreases, thereby causing the steam to act like a wedge
outwards, and lift the valve considerably more than in the case of the ordinary
valves before named.
The object of my improvemcuts is to also deliver a quantity of steam
through a small valve equivalent to that delivered through a large valve of
the common construction, and thereby save expense. In some cases my
improved valve, one square inch in area, will deliver as much steam from the
same boiler as the common valve of twelve times the area.
My improvements in steam boilers consists in a combination of single and
double rivetted joints, the object being to make a stronger boiler from the
same thickness of plates than can be made by the ordinary plan of con-
struction. For this purpose I use double rivetted joints for the longitudinal

page_text: joints of the shells of steam boilers and single rivetted joints for those passing
around the circumference of the shell. This combination makes the boiler
nearly as strong as if the shell had no rivetted joints at all.
The distance of the rivets asunder are such that the plates between the
rivet holes are just on the point of being torn asunder when the rivets are just
on the point of being sheared across, thereby giving the strongest form of
joint, and this is to be ascertained by testing the samples of iron to be used
as to thier tensile and shearing properties, after which the following formula
will give the strongest form of joint s
Single rivetted joints p=+d
2 as
Double rivetted joints p₁=+d
tn
where p is the pitch of the rivets for single joints in inches; d, the diameter
of the rivet in inches; a, the area of the rivet in inches; t, the thickness of
the plates in inches; s, the number to be found experimentally of pounds
required to shear one square inch of section of iron in the form of rivets;
n, the number of pounds to be found experimentally required to tear asunder
one square inch of section of the boiler plate left between the rivet holes after
punching or drilling; P₁, the pitch of the rivets in inches for double-rivetted
joints.
Having thus described the nature of my Invention, and the manner in
which the said Invention is to be performed, I wish it to be understood that
what I claim is,―
Firstly, the safety valve and combination of parts, herein described, set forth,
and in part illustrated.
Secondly, the manufacture of steam boilers with thier rivetted joints, con-
structed according to experiments and formula, herein set forth.
In witness whereof, I, the said Thomas Baldwin, have hereunto set
my hand and seal, this Sixth day of March, in the year of our Lord
One thousand eight hundred and sixty-seven.
THOMAS BALDWIN. (L.S.)