Improvements in Fire and Water Tubes for Steam Boilers.
Year: 1892

page_text: Date of Application, 22nd Jan., 1892-Accepted, 27th Feb., 1892
COMPLETE SPECIFICATION.
Improvements in Fire and Water Tubes for Steam Boilers.
I, MAX MANNESMANN, of Remscheid, Bliedinghausen, in the Empire of
Germany, Engineer, 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 :-
Fire tubes and water tubes of steam boilers are mostly constructed as cylindrical
tubes of equal thickness throughout; in consequence hereof they become unser-
viceable after a certain time, although still in great part sound, in consequence of
their being burnt away and destroyed at those parts that are more directly in
contact with the flames and heat of the furnace.
It is sometimes endeavoured to render such tubes serviceable again by cutting
off the burnt part and brazing or welding on a new piece in lieu thereof.
If it were endeavoured to increase the durability of tubes of uniform thickness
by increasing such thickness, on the one hand the heat conducting power of the
tubes would be greatly reduced and on the other hand the tubes would be corre-
spondingly increased in weight, which would be particularly prejudicial in the case
of tubes for moveable boilers such as locomotive boilers, or marine boilers.
My present invention relates to a construction of fire or water tube which at the
end which is exposed to the fiercest fire heat, is made with comparatively thick
sides, while at the other end it is. made thinner, the reduction in thickness being
either effected gradually along the entire length of the tube or it may be effected
more or less suddenly in step form, and it may be in the form either of a straight
line or of a curved line, the thinner end being if necessary made with a short
thickened part.
The external surface of the tube may, at will, be either of uniform diameter
throughout, or stepped, as shewn in the longitudinal section at Fig. 1. of the
accompanying drawing, or it may be conical or tapering, as at Fig. 2.
By this
means a fire or water tube is obtained which, with the same medium thickness, so
as not to exceed the weight of a tube of normal thickness, is made at both ends of
increased thickness, and which can consequently be secured more firmly and
durably by expanding in the tube plates, such tubes being more enduring as regards
the before mentioned unequal wear through burning and other deterioration by
heat, than tubes of uniform normal thickness.
Fig. 1. of the drawing shews a longitudinal section of a tube of gradually
decreasing thickness in the direction from one end to the other the extreme end of
the thinner part being thickened.
Fig. 2 shews a tube, the external surface of which is tapered in a straight line,
the metal being of decreasing thickness from one end to the other according to a
curved line.
Fig. 3 shows a tube of uniform internal diameter and of stepped external
diameter.
Fig. 4 shews a tube of both internal and external stepped diameters and of
increased thickness at the smaller end.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. A fire or water tube which is either of uniform or of tapering, conoidal, or
stepped external diameter, and is of gradually decreasing thickness either according
to a straight or a curved line or in stenued form substantially as described.

page_text: 2. In fire or water tubes of the kind referred to in the preceding claim,
providing the thin end thereof with a thickening substantially as described.
Dated this 22nd day of January 1802
ABEL & IMRAY,
Agents for the Applicant.