IMPROVEMENTS IN THE CONSTRUCTION OF HAND HOLE SEATS FOR STEAM BOILERS
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, CHARLES ALBERT KNIGHT, of 107 Hope Street, Glasgow, in the county of
Lanark, Engineer, do hereby declare the nature of my said Invention for
'IMPROVEMENTS IN THE CONSTRUCTION OF HAND HOLE SEATS FOR STEAM BOILERS,"
(A communication to ine from abroad by The Babcock & Wilcox Company of New
York United States of America, Water Tube Steam Boiler Manufacturers) 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 a new method of forming raised seats for hand-hole.
plates in that class of water tube boilers wherein the heating tubes are secured into
one of the sheets of a water box, the other sheet having hand holes placed directly.
opposite to the ends of the tubes and, at the same time, to give greater stiffness to
the plate, which is materially weakened by cutting out the hand-hole openings..
Various methods have been used to close such openings, such as internal hand-hole
plates of oval shape, as commonly used in the water tubes of locomotive and other
boilers, said plates being packed with rubber or other perishable packing. Those
packings have to be renewed each time the joints are opened for inspection or
cleaning, and are liable to leak through the burning out of the packing material.
Hand-hole plates have also been used on the outside of the sheets, scated directly
on the sheet without any packing, the sheet itself being finished off to make a
metal-to-metal joint with the hand-holo plato.
When the hand-hole plates are scated in the manner last described it is difficult
to replace them and secure a tight joint, as they have to be replaced exactly in the
original position, that portion of the seat not covered by the hand-hole plate
becoming corroded by exposure and is not suitable for forming a joint with the
hand-hole plate, and where the seat is on a level with the plate it is difficult to
refinish when once it becomes corroded..
Brass plugs have also been used, screwed into the outside plate, having taper
threads. These are liable to become stuck fast by accumulation of sediment or
rust and are difficult to remove; besides this the thread in the sheet is very apt to
become battered up during the operation of cleaning out the interior of the tubes,
D

page_text: To obviate these difficulties, and to stiffen the sheet so that the pressure of the
clamp which holds the hand-hole plate in position shall not tend to throw the
sheet out of shape, I have designed a new method of securing a raised hand-hole
seat, consisting of a ring of cast or wrought metal, faced off on one side to form a
joint with the hand-hole plate and secured to the sheet by means of an expanded
nipple, which fits tightly into the interior of the ring and the hole in the boiler
plate, being expanded into both so as to make a metal to metal contact, the same
as a boiler tube is expanded into its seat, the outer face of such rings being finished
off as a seat for the caps to shut against. These hand-hole seats, and the expanded
nipple which secures them to the sheet, may be of such internal diameter as to
allow the heating tubes to be drawn through them if it should become necessary
to replace them, as shown in Figure 2, in which a is the heating tube, 6 the hand-
hole seat, and c the expanded nipple which serves to secure the hand-hole seat in
position.
Where very thin plates are used for low pressures, or where heavy pressures are
to be used with ordinary thickness of plates, it becomes desirable to still further
stiffen the sheets through which the hand-hole openings are cut.
"
This is done by securing two rings bb, one on each side of the sheet through
which the hand-hole openings are cut, the nipple being expanded into both the
inner and outer rings and the intermediate plate, forming a tight joint with all
three pieces, as shown in Figure 1. In some cases, where the heating tubes are
prolonged through the water space and are expanded into both the inside and
outside sheets of a water box, the hand-hole rings, or seats, may be secured to the
end of the heating tube itself, as shown at b in Figure 3, wherein the end of the
heating tube is shown expanded into the ring forming the hand-hole face, as well
as into the two sheets forming the water box.
For the purpose of more firmly securing the ring to its connecting nipple the
interior of the ring may bo flared outwardly as shown at d, or a groove may be
made towards the outer face of the ring, as shewn in the rings b, b, Figures 1 and 2.
The flare or groove serves the purpose of allowing the end of the nipple to be
increased in diameter when it is expanded, thus effectually preventing it from
becoming displaced by pressure or otherwise.
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,―
First. A raised hand-hole seat consisting of a ring of metal, secured in position
by_means of an expanded nipplo.
Second. A ring forming a raised band-hole seat on one side of a sheet of metal
and a stiffening ring on the opposite side, in combination with a nipple expanded
into the inside and outside rings and the intermediate plate.
Deted this First daw of October 1991