Improvements in Boiler Tube Ferrules.
Year: 1898

page_text: Date of Application, 11th Oct., 1898-Accepted, 28th Jan., 1899
COMPLETE SPECIFICATION.
Improvements in Boiler Tube Ferrules.
I, GEORGE WESLEY DUVALL, of No. 133, Bermuda Street, Norfolk, County of
Norfolk, State of Virginia, United States of America, Machinist, 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:-
The object of the present invention is to provide better means than have here-
tofore been employed for preventing boiler-tubes from leaking and for closing
such leaks when they occur at the junction of the tubes with the tube sheet.
In some ferrules hitherto employed the tube forms the backing for the key,
when it is driven in, and thus it exerts great pressure on the tube as well as
on the split ferrule. Consequently on hard driving it is apt to split the ferrule.
In the present case I overcome this defect by forming the ferrule and key with
interfitting edges constituting guide ways for the key wedge. The key conforms
in curvature to the cylindrical ferrule and forms a wedge section thereof, and
by which it is supported and held. Thus the key is entirely free from the tube,
whilst it is being driven home and though completing the circle of the ferrule
and protecting any weak spot in the tube opposed thereto, it cannot bind against
the tube, whilst it is being driven, and split it. Then again as the key does not
bind against the tube it allows a close fit of the ferrule to the tube.
It is well known that when the end of a boiler tube is attached to
the flue sheet it becomes larger from the action of the rolling tool, and the
ferrule is made with an enlargement of its diameter just below the flange to
conform to the enlarged end of the fluc.
In the drawings:-
Fig. 1 is a perspective view of a ferrule fitted into a boiler flue, without the
key being in place;
Fig. 2 is a transverse section through the tube, ferrule and key;
Fig. 3 is a longitudinal section on the line 2-2, of Fig. 2, the same showing
the key in place; and
Fig. 4 is a perspective view of the key.
A is the tubular ferrule made with the curved flange, B, to fit over the beaded
end of the tube C, and against the face of the tube sheet D, the said flange
having one or more slots b, in addition to the cut b', contiguous to the key-
seat A¹. The ferrule is formed with the swell or enlargement at a, conforming
to the expanded end of a tube C.
The key wedge E is preferably curved to conform to the radius of the ferrule,
and it has its side edges e, e; rounded, the same engaging the grooved ways a¹
in the sides of the key-seat. The guide-ways a being formed by grooving out
the edges of the walls of the slot 6, retaining lips or edges are produced which
hold the key in position within the guide-ways and prevent it from slipping out
laterally. This is important as it avoids any liability of the key being driven
out of a straight course and coming in contact with the inner surface of the
Price 8d1

page_text: boiler tube. By this construction of guide-ways, it is manifest that the wedge
shaped key can only be inserted from the flange end of the ferrule.
The grooved way is centrally located in the metal constituting the ferrule so
that when the key is entered therein, it will not project beyond the edges of
the key seat but will be flush therewith so that it will not impinge against the
inner wall of the tube, while being driven in. I regard this as an important
feature of my invention as with my former construction the key came in con-
tact with the inner wall of the tube and in some instances, where the tube was
weak, it was broken during the driving action. I experienced these difficulties
with my former constructions and as a result of considerable thought and experi-
ment devised this improved construction. These guide ways may of course be
angular, or otherwise formed, so that the key wedge engages with and slides
in the ferrule and is held by the same. Upon an examination of Figure 4 of
the drawing, it will be seen that the key has four curved surfaces and two
bevelled surfaces, while in my former patents the key is merely wedge shaped
and has no curved surfaces. With my new construction of key and by provid
ing the grooved ways in the ferrule for the key to slide in, one blow has the
effect of three blows on the old construction of key. The ways retain the key
and guide it perfectly during the driving action so that it cannot possibly come
in contact with the inside of the tube.
To apply a ferrule to a boiler tube, the ferrule is inserted into the end of the
tube after first applying thereto red lead or other suitable substance to the end
of the tube, and the key is driven home, expanding the ferrule uniformly
against the interior surface of the tube around the entire circumference without
any binding or excess of pressure along the line of the key. Consequently not
only the tube is not injured by the key but it requires fewer blows to seat it.
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:-
1. A split hollow tube ferrule having a flange and provided with a longitudinally
arranged slot for the reception of a key, the walls of the slot being provided
with longitudinal guide-ways, and a wedge shaped key which is entered into the
ways from the flange end of the ferrule and is confined and guided by said
ways, the outer surface of the key when the key is in position within the slot,
being flush with the outer surface of the ferrule, substantially as described.
2. A split hollow tube ferrule having a flange provided with a curved under
surface which receives the head on the outer end of the boiler tube, said ferrule
being provided with a longitudinally arranged slot for the reception of a key,
the walls of the said slot being provided with longitudinal grooved guide ways,
having retaining edges and a wedge shaped key which is curved in cross section
to conform to the curvature of the ferrule, which key is entered into the ways
from the flange end of the ferrule and is retained and guided by said ways, the
key being confined within the guide ways so as not to project beyond the outer
surface of the ferrule, substantially as described.
3. A split boiler tube ferrule having a flange provided with a curved under
surface which receives the bead of the outer end of the boiler tube, said ferrule
being thickened or enlarged all round at a point adjoining the flange to conform
to the expanded end of the boiler tube, and also provided with a longitudinally
arranged slot, which extends through the flange of the ferrule for the reception
of a key, the walls of the said slot being provided with longitudinal guide ways
and a wedge shaped key which is entered into the ways from the flange end of
the ferrule and is confined and guided by said ways so as not to come in contact
with the inner surface of the boiler tube when being driven in, substantially
as described.
4. A split hollow tube ferrule having a flange provided with a longitudinally

page_text: arranged slot for the reception of a key, the walls of the slot being provided
with longitudinal guide ways, and a wedge shaped key which is curved in cross
section to conform to the curvature of the ferrule, the said key being entered
into the ways from the flange end of the ferrule and retained and guided by said
ways, the key falling entirely within the metal constituting the ferrule so as not
to project beyond the outer surface of the same and come in contact with the
inner surface of the boiler tube when being driven in, substantially as
described.
Tlated this 11th d
1000