IMPROVEMENTS IN THE USE AND APPLICATION OF SUBSTANCES FOR PRE- VENTING THE ESCAPE OF HEAT FROM THE SURFACES OF CYLINDERS, BOLLERS, AND OTHER VESSELS OR APPARATUS CONTAINING HEAT
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by James Howden at the Office
of the Commissioners of Patents, with his Petition, on the 5th
October 1868.
I, JAMES HOWDEN, of Glasgow, in the County of Lanark, North
Britain, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE USE AND APPLICATION OF SUBSTANCES FOR PRE-
VENTING THE ESCAPE OF HEAT FROM THE SURFACES OF CYLINDERS, BOLLERS, AND
OTHER VESSELS OR APPARATUS CONTAINING HEAT," to be as follows:-
My Invention relates to the employment of plaster of Paris or other
non-conducting substances having similar properties, rendering them
capable of being run into moulds or spaces in a liquid or semi-liquid
state and of rapidly solidifying thereafter, for enveloping the surfaces of
cylinders, boilers, pipes, or other vessels containing heat so as to protect
the heat from the cooling effect of a lower surrounding temperature or the
surrounding temperature from being increased by the higher temperature
of the vessel. This has hitherto been effected in a degree more or less
perfect by covering the surfaces to be protected with sheets of hair felt,
which are again covered by wood, sheet iron, lead, or canvas, or instead of
hair felt such non-conducting compositions are used as those known as

page_text: is
Spence's, Leroy's, and others, where the material is applied in a plastic
state to the surface in successive layers, which are dried one by one by
heat (which must be maintained in the vessel during the process) until
the desired thickness is obtained. The application of these substances
is in consequence tedious and expensive, besides being in many cases
very difficult. In applying the non-conducting substances according to
my Invention, the vessel or surface to be protected is surrounded wholly
or in part by an envelope of sheet iron, wood, or other suitable material
placed at a distance apart from the surface equal to the thickness
required for the non-conducting material. The plaster of Paris or similar
substance is then made up in its liquid state and run or poured into the
space between the envelope and surface of the vessel until the space
filled. In a few minutes the material is solidified without the application
of heat. The envelope may afterwards either be removed or allowed to
remain; when it is removed the surface of the non-conducting substance
may be painted, varnished, or similarly treated, so as to make it entirely
impervious to rain when in an exposed situation, and also to give it an
elegant and finished appearance. It is not always necessary that the
whole surface of any vessel should be covered at once, as the envelope or
mould may be made to extend only over a certain part of the vessel to
be protected at a time, and after the portion so covered by the envelope
is filled up the envelope may be removed to the part of the vessel
adjoining and the process repeated in like manner until the whole is
covered with the non-conducting material. In cases also where the
surface to be protected is lying horizontally it is not always necessary to
have the envelope on the upper face. Projections may then be made
round the outer edge of a height equal to the depth desired for the non-
conducting material, and the material poured over the surface until it
rises to the level of the outer edging. In protecting removable covers of
vessels such as are fastened with bolts according to this Invention it is
preferred to have an outer case of iron, wood, or other suitable material
to be placed over and fastened to the cover. Into this case, which is
slightly hollow, the non-conducting material is poured so as to fill up
the entire space, but leaving hollows or spaces inside for the nuts or bolt
heads. These cases are easily removed from the bolted cover of the
vessel when access is required. In protecting such vessels as steam
cylinders where the envelope is generally permanent, it is not necessary
to have any holes in the envelope itself by which to pour in the pro-
tecting material. The material may if desired be poured in through a

page_text: few small holes in the cylinder flange leading into the space to be filled
up. When vessels with flanges, such as pipes, are protected according
to this Invention the non-conducting material may be put on from
flange to flange, or it may be made to cover the flanges so as to leave
no metal of the vessel or vessels exposed. When it is desired to have
access to the bolts or fastenings of the flanges without disturbing the
non-conducting material, it is then put on the body of the pipe or other
vessel to within a distance from the flanges sufficient to give access to
the bolts or fastenings. To protect the vessel thoroughly in such cases
the flanges and spaces left for the fastenings are covered up with an
envelope in two or more pieces, each filled with the non-conducting
material, the envelope being easily removable when access to the
fastenings is wanted.
A modification also comprehended in this Invention may be used in
cases when a permanent envelope is fitted round the vessel to be pro-
tected, where instead of the non-conducting material being poured into
the space between the vessel and the envelope in a liquid state, it may
be run in dry as a powder into the space to be filled. It is not necessary
in this application of the material that it should in all cases have the
property of solidifying after being mixed with water, as such non-
conducting substances as charcoal, capable of being reduced to a
granulated or powder state, may be used.
Another modification of the improvements comprehended under this
Invention consists in mixing plaster of Paris and lime together in about
equal proportions, and making a workable plaster thereof capable of
being applied with a trowel. The non-conducting plaster formed by
this mixture may be applied to surfaces to be protected without the
envelope being used at the time of application. It is capable of adhering
to iron or other metals, and of solidifying in about one hour without the
application of heat; after solidifying it can either be used with an
envelope or without. With this plaster now described and with the
non-conducting substances when poured into the mould in a liquid state
a small quantity of gelatinous or glutinous material may be mixed when
desired.