An Improved Process and Furnace for the Production of Boiler and similar Tubes.
Year: 1899

page_text: Date of Application, 19th Apr., 1899--Accepted, 24th June, 1899
COMPLETE SPECIFICATION.
An Improved Process and Furnace for the Production of Boiler and
similar Tubes.
I, HENRI WOLTERS, Engineer, of Seraing, in the Kingdom of Belgium, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
-
The object of the present invention is a process for the production of tubes
(more especially locomotive boiler tubes), the essential feature of which is, that
the various necessary phases of treatment of the material are carried out in chambers
to which flame is directly admitted, and in chambers indirectly, that is to say,
externally, heated, whereby the formation of a film of oxide on the outer surface
of the tubes, is prevented in the greatest possible degree, and thus tubes are
obtained with a bright outer surface. The invention also relates to a combination
furnace for carrying out the above mentioned process.
In the accompanying drawing is shewn a furnace designed to carry out the
process, and constructed to meet the practical necessities.
Fig. 1 is a longitudinal section of the improved furnace, on the line A-B of
Fig. 2.
Fig. 2 is a horizontal section of the same.
Fig. 3 is a cross section, on the line C-D; and
Fig. 4 is a cross section on the lines E-F of Figs. 1 and 2.
The proces is preferably carried out in the following manner;-After the tubes
have been heated in the usual way, in a directly or internally heated chamber, to
permit of the rolling taking place, they undergo a preliminary heating in a second
chamber, indirectly or externally heated by the fire gases; and are subsequently
transferred to a third directly fired chamber, and there brought to a sweating heat,
the sweated tubes being then passed for the first time to the draw bench (the
residual heat remaining over from the sweating being here utilized), and, finally,
heated afresh in a second indirectly heated furnace chamber, after which they
pass to the final calibration process, that is to say, the tubes undergo a second
drawing.
As, during the four operations above described, the tubes are only exposed
directly to the fire twice, they are only exposed twice to the oxidizing influence
on their outer surface, instead of four times, as is the case with the methods
hitherto in use. In this way the tube acquires such a quality of outer surface
that the hitherto usual cold drawing, after dipping the tubes in a bath of sulphuric
and hydrochloric acids, is no longer necessary. On the contrary, by the improved
process, a finished tube ready for use is obtained with a perfectly faultless outer
surface.

page_text: For the purpose of carrying out the process, a special furnace is employed, which,
to obtain the direct and indirect heating of the several chambers, is a combination
furnace.
The best method is to have two separate firings for the four chambers, in such
manner that the first and third chambers are directly fired, while the second and
fourth receive the temperature of the exhaust gases, or (in other words) the heat
radiated from the directly fired chambers.
The special features of the furnace construction selected for illustration are
clearly shewn in the figures of the drawing.
The first fire, a, is directly connected with the heating space I. From the rear
portion of the space a, a flue 6 leads to the main flue. The second fire c is directly
connected with the heating chamber III by one or more flues. From the rear
portion of this latter, branches off the flue d, which surrounds the upper portion of
the heating chamber IV. The flue d leads to the main flue of the furnace. The
exhaust gases, which pass off from the fire a, before reaching the main flue, strike
along on the under portion of the jacket of the heating chamber IV externally
so that this latter receives the heat of the spent gases by radiation, both on its
upper and lower parts.
Between the fire c and the heating chamber III, is interposed the heating
chamber 1. This latter, which is situate in the masonry between c and III, is
heated at its front end by the gases issuing from the fire c, and at its rear end by
the heat radiated from the fire a.
When employing a furnace like that above described, the process is carried out
in the following manner.
After the plate which is to form the tubes has been heated in the usual way
in the directly fired chamber I, prior to the rolling operation, the sheet, when
rolled, is first heated up to a red heat in the indirectly fired chamber II, then
transferred to the directly fired chamber III, to be there raised to a sweating heat,
after which it undergoes the first drawing (the residual heat from the sweating
operation being utilized here), as, for example, in the case of locomotive boiler
tubes from 63 down to 57 millimetres in diameter. Finally, the tube is again
heated in the indirectly fired chamber IV, and then passes to the final calibration
(in the case of locomotive tubes, the tubes are brought from a diameter of 57 mm.
down to 51 mm.)
As has already been remarked, in the present process the outer surface of the
tube is only exposed to oxidation twice, instead of four times, during its manipula-
tion, so that the final result is considerably superior to that attained by the use
of the process hitherto employed.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I claim
is:
1. Process for the production of tubes characterised by the fact that the various
operations are carried out alternately in the presence of direct and indirect heat
(said indirect heating being effected preferably by radiation), for the purpose of
preventing the formation of a film of oxide upon the outer surface of the tube,
and producing a bright outer surface.
2. A mode of carrying out the process claimed in Claim 1, characterised by the
fact that the material, heated in the usual way by direct contact with the fire
(chamber 1), for the purpose of the rolling operation, is brought to a red heat in
à second furnace (chamber II), indirectly heated by the fire gases, then brought to
a welding heat in the directly heated chamber III, the welded tube passing to the
drawbench for the first drawing (the residual heat from the welding being here
utilized), and finally again heated a second time in an indirectly fired furnace
(chamber IV), for the purpose of the final calibration.
3. A furnace for carrying out the process of Claim 1, consisting of four chambers,

page_text: of which the first and third are directly fired, while the second and fourth have
the temperature of the spent gases or radiated heat of the directly fired chambers.
Dated this 19th day of April 1899
NEWTON & SON,
Agents for the Applicant.