IMPROVEMENTS IN THE LAGGING' OR COVERING OF STEAM BOILERS, STEAM CHESTS, STEAM PIPES, HOT BLAST PIPES, ICE HOUSES, REFRIGERATORS, FIREPROOF ROOMS, SAFES, WATER & GAS PIPES, &C. FOR THE PURPOSE OF PREVENTING THE TRANSMISSION OF EITHER HEAT OR COLD, OF ARRESTING THE SPREAD OF FIRE
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Robert Stewart at the Office of the
Commissioners of Patents on the 22nd February 1876.
ROBERT STEWART, of 140, Leadenhall Street, Engineer. "IMPROVEMENTS IN
THE LAGGING' OR COVERING OF STEAM BOILERS, STEAM CHESTS, STEAM PIPES,
HOT BLAST PIPES, ICE HOUSES, REFRIGERATORS, FIREPROOF ROOMS, SAFES,
WATER & GAS PIPES, &C. FOR THE PURPOSE OF PREVENTING THE TRANSMISSION
OF EITHER HEAT OR COLD, OF ARRESTING THE SPREAD OF FIRE."
"
The Invention consists of a peculiar application of an article called "silicate
cotton which is made from "slag" from blast furnaces, by jets or blasts of steam,
or superheated steam, or air, or any other well known process discharged upon and
into the hot slag when issuing from the furnace, thus transforming it into a cotton-
like state, also known as "slag wool" or "furnace wool." The principal reason
why this furnace wool" has so far not been utilized for the above purpose is because
it could not be made to adhere to vertical sides, nor kept together for any length of
time in a compact mass owing to its loose and fluffy and non-adhereing nature and
the entire absence of any fibrous quality to enable it to be spun or woven. I,
therefore, fill this "silicate cotton into a kind of mattress (see Figs. 1 & 2) made
of canvas, sail cloth, linen, or similar material, or of thin closely woven wire
gauze, one foot broad, 21/2 inches thick, and cut any length, according to the dimen-
sions of the surface to be covered. The material has to be pressed in as firmly as
possible, and when the "mattresses are closed up they have to be stitched through
and through in rows four inches apart in a manner somewhat similar to ordinary
mattresses. These "mattresses" have to be put on and sewn together as closely as
possible over the surface to be covered, such as boilers, steam chests, &c., after which
strips of galvanized wire fencing or netting, about two feet wide with meshes of an
inch wide have to be closely drawn and fastened over the whole of the mattresses.
To fasten them still more securely and give the whole a still greater amount of
firmness and stability, iron hoops 11 inches broad have to be fastened over the
netting about three feet apart and screwed together at the ends, where they meet, or
on to a rod or other fastening at the sides of the boilers, so that they could easily be
undone for effecting repairs. The whole has then to receive a good coating of tar so
as to present a water proof surface and to prevent the canvas from rotting.
certain cases I also fasten strips of wood, about one foot broad and about two feet
D
71
"
In

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apart, over the whole covering as described above, so as to enable workmen to
stand on and walk over the boiler for the purpose of effecting repairs; or instead
of the wire netting I substitute sheets of perforated galvanized iron 1/20 of an
inch thick and about 21%, feet broad, and fasten them with iron bands slung across
and screwed together at the ends, or at the sides of the boiler, so that they may be
easily removed for effecting repairs. For covering small pipes, tubes, &c., with the
same material, I employ a kind of casing (see Figs. 3 & 4) of zinc or tin, or
other suitable material about 1/, feet long, cut open on one side, so that it can be
clasped round any size of pipe and kept at a uniform distance from the pipe by
brass screws fitted at one end, so as to have an equal space between it and the
tubes. The "silicate cotton" is then filled and pressed closely into the space and
when full the casing is pulled further along the pipe, and as the "silicate cotton
is laid bare it is wound round with strips of canvas (see Fig. 5), which latter are
again tied round with galzanized iron wire, after which the whole is thoroughly
tarred over.
و"