Improvements in Steam Boilers and other Vessels Subjected to Internal Pressure.
Year: 1889

page_text: Date of Application, 6th Apr., 1889
Complete Specification Left, 24th Dec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in Steam Boilers and other Vessels Subjected to
Internal Pressure.
1, CARL SCHAEFER, of Sect. IV No. 74 Würpenborgstrasse, Oberhausen, Rhine
Province, Kingdom of Prussia, German Empire, do hereby declare the nature of this
invention to be as follows:―
This invention relates to an improvement in steam boilers and other vessels
subjected to internal pressure. It is a fact well known that the ever increasing
pressure of steam required for steam boilers, and more particularly marine boilers,
necessitates the employment of sheet iron or steel, of such a thickness as to render
it impossible, or nearly impossible, to work the said sheet metal into boilers by
means of the ordinary appliances as now commonly in use in even the larger boiler
factories. Moreover, it is known that in bending into the shape of boilers, sheet-
metal of great or unusual thickness, the material of the said metal is very apt to
become distorted and strained by reason of the external fibres which are more
distant from the neutral layer, being stretched too much, whilst the layer of fibres
on the interior surface are compressed in too high a degree, so that the strength
of the sheet metal after being bent into form is materially diminished and impaired ;
lastly it is to be remarked that the cost of sheet metal increases in undue proportion
to the greater weight due to the increasing thickness.
Now, in order to obviate the above difficulties it is proposed, according to the
present invention, to employ for the shells of boilers and other vessels intended for
high pressure, in lieu of a single plate of sheet metal having the required thickness,
two or more superposed sheet metal plates of reduced thickness so that the severaĺ
combined thicknesses of the said several plates, will equal the thickness which a
single sheet metal plate would require to have, if used for the construction of the
boiler.
The
Thus, if, for instance, a boiler shall require to have a thickness of 2 inches, then.
according to the present invention, instead of a single metal plate having the said
thickness, two sheets of 1 inch each, or three sheets of d inch each, or four sheets
of inch each would be taken and connected together in a suitable manner.
connecting of the said sheet metal plates is preferably effected in such manner that
the one plate will cover the joint between two other plates, and that the said joint
is, at the same time, connected by means of a rivetted fish-plate. It is also deemed
advisable to provide with suitable fish-plates all the circumferential and longitudinal
joints on the outside, and the longitudinal joints on the inside of the boiler, the
circular joints on the interior requiring to be covered up by a fish plate only in
case of extremely high pressure being employed.
On the accompanying drawings the longitudinal and transverse sections, Figs. 1,
and 2, illustrate two arrangements for carrying the above described invention into
effect.
Referring first to the steam boiler indicated in Fig. 1 it will be seen that the shell
of the boiler is formed of two superposed sheet metal plates a and b ; c c designate
interior and d d exterior fish-plates for the circular joints, whilst e e are interior
and ff. exterior fish plates for the longitudinal joints.
Referring next to Fig. 2, the boiler shell is there constructed of three superposed
plates hi and k and fish plates l m n and o for the interior, intermediate and exterior
circular and longitudinal joints. It will be readily seen that the boilers constructed
as above described, consist of a shell, having, as it were no joint at all, there being in
fact no joint extending through more than one half, or one third etc., of the total
thickness of the metal.

page_text: Moreover, it is evident that, considering the fact that the entire length and width
of each metal plate always covers up the joints of the adjacent plates, a more reliable
connection of the several plates as well as a more perfect closing up of the joints is
ensured by reason of the broader cover surrounding the said joints.
By means of the above arrangements. I am enabled to increase to any desired
thickness the shells of steam boilers without resorting to the use of sheet metal plates
of proportionately increasing thickness, and thus to produce from relatively thin
plates, boilers having large diameters and capable of sustaining the highest possible
pressures, while the manufacture of such boilers from thin plates can be readily
effected by means of the plant and appliances heretofore in use in boiler work-shops,
and at a greatly decreased cost as compared with that of boilers made of a single
thickness of plate.
COMPLETE SPECIFICATION.
Improvements in Steam Boilers and other Vessels Subjected to
Internal Pressure.
I CARL SCHAEFER of Sect. IV No. 74 Würpenborgstrasse, Oberhausen, Rhine
Province, Kingdom of Prussia, German Empire, do hereby declare the nature of this
invention, and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
This Invention relates to an improvement in steam boilers and other vessels
subjected to internal pressure. It is a fact well known, that the ever increasing
pressure of steam required for steam boilers, and more particularly inarinė boilers,
necessitates the employment of sheet iron or steel of such a thickness as to render it
impossible, or nearly impossible to work the said sheet metal into boilers by means of
the ordinary appliances as now commonly in use, in even the larger boiler factories.
Moreover it is known that in bending into the shape of boilers sheet metal of
great or unusual thickness, the material of the said metal is apt to become
distorted and strained by reason of the external fibres, which are
more distant
from the neutral layer being stretched too much, whilst the layer of fibres on
the interior surface are compressed in too high a degree, so that the strength of the
sheet metal after been bent into form is materially diminished and impaired; lastly it
is to be remarked that the cost of sheet metal increases in undue proportion to the
greater weight due to the increasing thickness.
Now, in order to obviate the above difficulties it is proposed according to the present
invention; to employ for the shells of boilers and other vessels intended for high
pressure, in lieu of a single plate of sheet metal having the required thickness,
two or more superposed sheet metal plates of reduced thickness, so that the several
combined thicknesses of the said several plates will equal the thickness which
a single sheet metal plate would require to have if used for the construction of
the boiler,
The
Thus, if for instance a boiler shall require to have a thickness of 2 inches, then
according to the present invention, instead of a single metal plate having the said
thickness, two sheets of 1 inch each, or three sheets of d inch each, or four sheets of
inch each would be taken and connected together in a suitable manner.
connecting of the said sheet metal plates is preferably effected in such a manner that
the one plate will cover the joint between two other plates, and that the said joint is
at the same time connected by means of a rivetted fishplate. It is also deemed
advisable to provide with suitable fishplates, all the circumferential and longitudinal
joints on the outside, and the longitudinal joints on the inside of the boiler, the
circular joints on the interior requiring to be covered up by a fish plate, only in case
of extremely high pressure being employed.
On the drawings accompanying my provisional Specification, the longitudinal and

page_text: transverse sections, Figures 1 and 2 illustrate two arrangements, for carrying the above
described invention into effect.
Referring first to the steam boiler indicated in Figure 1 it will be seen that
the shell of the boiler is formed of two superposed sheet metal plates a and b:
c. c. designate interior and d d exterior fish plates for the circular joints; whilst
ee are interior, and ff exterior fish plates for the longitudinal joints.
Referring next to Figure 2, the boiler shell is there constructed of three super-
posed plates h, i kand fish plates l. m. n. and o for the interior circular and longitudinal
joints. It will be readily seen that the boilers constructed as above described
consist of a shell having as it were no joint at all there being in fact no joint
extending through more than one half, or one third etc. of the total thickness of the
metal.
Moreover it is evident that considering the fact that the entire length and width
of each metal plate always covers up the joints of the adjacent plates, a more reliable
connection of the several plates, as well as a more perfect closing up of the joints
is ensured by reason of the broader cover surrounding the said joints.
By means of the above arrangements am enabled to increase to any desired
thickness, the shells of steam boilers without resorting to the use of sheet metal plates
of proportionately increasing thickness, and thus to produce, from relatively thin
plates, boilers having large diameters and capable of sustaining the highest possible
pressures while the manufacture of such boilers from thin plates can be readily
effected by means of the plant and appliances heretofore in use in boiler workshops
and at a greatly decreased cost as compared with that of boilers made of a single
thickness of plate.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what I
claim is :-
The improved construction of steam boilers and other vessels subjected to internal
pressure wherein the shells thereof are formed of two or more superposed layers
of sheet metal in such manner that the butt joints of the plates of one layer are
covered by the plates of another layer which serve at the same time as fish plate to
the joint, thus producing a shell, the joints of which only extend through a fractional
part of the casing substantially as herein described.
Dated this 24th day of December 1889.
ABEL & IMRAY,
Agents for the Applicant.