Improvements in Fire-boxes for Boilers.
Year: 1895

page_text: Date of Application, 14th June, 1895
Complete Specification Left, 20th Feb., 1896-Accepted, 21st Mar., 1896
PROVISIONAL SPECIFICATION.
Improvements in Fire-boxes for Boilers.
I, FERNAND TRIGALLEZ, of Nisch, in the Kingdom of Servia, Chief Engineer
of the State Railway Works, do hereby declare the nature of this invention to be
as follows:-
This invention relates to fire-boxes of boilers and has for object an improved
method of bolting together the inner and outer shells of fire-boxes.
Hitherto it has been the practice to connect the two shells together by screwing
stay-bolts through the same, the ends of the stay-bolts, which project through both
the inner and outer shell, being riveted or spread out by hammering to obtain the
desired tightness of joint. This method has many disadvantages of which the
most important are the weakening of the inner shell by the holes through which
the stay-bolts pass, the necessity of frequent caulking caused by the loosening of
the joint from the wearing of the screw-threads and of the heads of the stay-bolts
exposed to the direct action of the fire, and the production of cracks in the shells
which extend ultimately from bolt to holt. The above results give rise to serious
expense and shorten the life of the inner shell.
According to my invention I screw the stay-bolt through the outer shell but,
instead of screwing it through the inner shell, I only screw it to a certain distance
into the same and I thicken the inner shell, on the side in contact with the water
in the boiler, at the parts where the bolts enter so that the screwed end of the
stay-bolt penetrates the inner shell to a depth equal to the thickness of the same
so that the strength of the joint is in no way diminished.
Dated this 14th day of June 1895.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
Improvements in Fire-boxes for Boilers.
I, FERNAND TRIGALLEZ, of Nisch, in the Kingdom of Servia, Chief Engineer
of the State Railway Works, 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 fire-boxes of boilers and has for object an improved
method of bolting together the inner and outer shells of fire-boxes.
Hitherto it has been the practice to connect the two shells together by screwing
stay-bolts through the same, the ends of the stay-bolts, which project through both
the inner and outer shell, being rivetted or spread out by hammering to obtain the
desired tightness of joint. This method has many disadvantages of which the
most important are the weakening of the inner shell by the holes through which
the stay-bolts pass, the necessity of frequent caulking caused by the loosening of
the joint from the wearing of the screw-threads and of the heads of the stay-bolts
exposed to the direct action of the fire, and the production of cracks in the shells
Price 8d 1

page_text: which extend ultimately from bolt to bolt. The above results give rise to serious
expense and shorten the life of the inner shell.
According to my invention I screw the stay-bolt through the outer shell but,
instead of screwing it through the inner shell, I only screw it to a certain distance
into the same and I thicken the inner shell, on the side in contact with the water
in the boiler, at the parts where the bolts enter so that the screwed end of the
stay-bolt penetrates the inner shell to a depth equal to the thickness of the same so
that the strength of the joint is in no way diminished.
To enable my invention to be fully understood I will describe how it can be
carried into practice by reference to the accompanying drawing, which is a section
of part of a fire-box illustrating my improved method of bolting together the inner
and outer shells thereof.
A is the stay-bolt, B is the non-perforated thickness of the inner shell, C is the
thickened part of the said shell preferably obtained by rolling and making up
from c to b the required depth of thread, that is to say, a depth equal to that
employed in existing fire boxes.
The outer part of the stay bolt is not in any way altered in principle. · ·
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In a fire-box for boilers making the screw threaded holes for receiving the stay-
bolts only partially through the thickness of the inner shell and thickening
the said inner shell on the side in contact with the water at the parts where
the stay-bolts enter it substantially as, and for the purpose, hereinbefore
described.
Dated the 20th day of February 1806
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.