AN IMPROVED MODE OF SECURING TUBES IN STEAM BOILERS AND OTHER VESSELS
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Dillwyn Smith at the Office
of the Commissioners of Patents, with his Petition, on the 17th
April 1868. A communication from abroad by George P. Hunt,
of the City, County, and State of New York, Engineer United
States Navy.
DILLWYN SMITH, of Burlington, New Jersey, United States of
America, now of No. 8, Southampton Buildings, Chancery Lane, in the
County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "AN IMPROVED MODE OF SECURING TUBES IN STEAM
BOILERS AND OTHER VESSELS," a communication, to be as follows:-
The nature of the said Invention consists in fitting the end of the
tube in a ferrule, which is constructed and screwed into the tube plate
in such a manner that it can be readily unscrewed to allow the tube to
be removed when required.

page_text: In the ordinary method of constructing tubular boilers and similar
vessels the plates which receive the ends of the tubes are drilled with
holes of a diameter corresponding with the exterior diameter of the
tubes; the latter being then inserted into the said holes a taper drift
or mandrel is forced into the end of each tube, which is thereby
expanded and caused to fit tightly in its hole. In some cases a ferrule
or ring is driven into the end of the tube to render it more securely
and perfectly steam-tight in the tube plate.
It will be seen that in the above described method of construction
the only security against the escape of the steam is that obtained by
forcing the tube tightly into contact with the surface of the hole in the
tube plate.
This surface is. very narrow and the tube is necessarily
weakened by being forcibly expanded at this point where its greatest
strength is required. The tubes also being thus forcibly expanded in
the tube plate, though often very imperfectly steam-tight, are very
difficult to remove when it becomes necessary to replace them with
others, such difficulty of removal being very serious in the boilers of
locomotive, marine, and agricultural engines.
In constructing multitubular boilers according to my Invention I
form a screw thread in the interior of the holes in the tube plate; into
these holes I fit ferrules or hoops of wrought iron or other suitable
metal, which are formed on their exterior surface with a screw thread
corresponding with that of the holes, the two threads being well fitted
together; these ferrules or hoops are bored out by preference slightly
taper and are fitted upon the ends of the tubes which are made of
corresponding shape. I then insert the tubes in the holes in the tube
plate and then screw the ferrules into the said holes. As the ferrules are
screwed in the taper surface of the ferrule and tube are brought gradually
into close contact and form a steam-tight joint of much greater area
of surface than can be obtained by the ordinary method of securing such
tubes and without injuring either the tube or the plate. The tubes when
thus secured may be readily and conveniently removed at any time
without injury to themselves or to the plates. To further facilitate
their removal I form notches or recesses in the rim of the ferrule. I
fix a disc upon one end of a bar or spindle, which disc is nearly of the
same size as the interior of the tube. Near the other end of the

page_text: spindle I attach a cross piece, which is formed to fit the notches in
the ferrule. The end of the spindle with the disc is inserted in the
tube and the spindle is thus kept steady while it is turned by a key or
spanner fitted to a square on its outer end.