IMPROVEMENTS IN BOILER TUBES
Year: 1881

page_text: LETTERS PATENT to Friedrich Hermann Felix Engel, Civil Engineer and
Patent Agent, in the City of Hamburg, Germany, for an Invention of
"IMPROVEMENTS IN BOILER TUBES." A communication from James Empson
& Co., Engineers, Boilermakers, and Shipbuilders, of Steinwärder, near
Hamburg, in the German Empire.
PROVISIONAL SPECIFICATION left by the said Friedrich Hermann Felix
Engel at the Office of the Commissioners of Patents on the 18th July 1881.
FRIEDRICH HERMANN FELIX ENGEL, Civil Engineer and Patent Agent, in the
City of Hamburg, Germany. "IMPROVEMENTS IN BOILER TUBES." A communi-
cation from James Empson & Co., Engineers, Boilermakers, and Shipbuilders, of
Stein warder, near Hamburg, in the German Empire.
This Invention relates to improvements in boiler tubes, and consists of forming
such tubes with a thread like or spirally corrugated surface instead of a plain
smooth surface, as has formerly been the case. The effect of this construction is to
provide for a greater heating surface of the tubes and less danger of leakage of the
boiler end plates as the expansion and contraction of the tubes when heated or
cooled off will act less powerfully upon the end plates. The tubes may either be
drawn or be pressed upon a lathe into the above described shape, but both ends of
each tube must remain smooth as formerly and have the same or a larger diameter
as the corrugation for the purpose of fitting the tubes to the boiler plates.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Friedrich Hermann Felix Engel in the Great Seal Patent Office
on the 18th January 1882.
FRIEDRICH HERMANN FELIX ENGEL, Civil Engineer and Patent Agent, in the
City of Hamburg, Germany. "IMPROVEMENT IN BOILER TUBES." A communi-
cation from James Empson & Co., Engineers, Boilermakers, and Shipbuilders, of
Steinwarder, near Hamburg, in the German Empire.
This Invention relates to improvements in boiler tubes, and consists of forming
such tubes with a thread-like or spirally corrugated surface instead of a plain
smooth surface, as has formerly been the case. The effect of this construction is to
provide for a greater heating surface of the tubes and less danger of leakage of the
boiler end plates, as the expansion and contraction of the tubes when heated or
cooled off will act less powerfully upon the end plates of the boiler. The tubes
may either be drawn or be pressed upon a lathe into the above described shape, but
both ends of each tube must remain smooth as formerly and have the same or
a larger diameter than the corrugation for the purpose of fitting the tubes to the
boiler plates.
Fig. 1 of the accompanying Sheet of Drawings represents part of such boiler tube
shown as broken off at the right hand side. A is the circular smooth end for
fastening the tube to the corresponding boiler plate, and B is the corrugated
threadlike formed part of said tube.
Fig. 2 represents one mode of manufacturing such improved boiler tubes out of
a smooth and plain tube C. The plain tube C is placed over a core-bar D of such
exterior shape as shall be given or formed to the inner wall of the boiler-tube, and
said rod or core D is therefore furnished with a thread like surface as far as the
tube is to be formed into such shape. The tube Cis fastened to the smooth end of
bar D, and the latter placed between the points of a lathe. By steel rollers or by
any other convenient mechanical arrangement the wall of tube C can be pressed
into the thread like deepening of core D whilst the latter is put in rotation, thus
producing the improved boiler-tube shown by Fig. 1, and the core may be removed
by an unscrewing motion.
Having now described the nature and particulars of the said Invention I
claim,―
The boiler tubes formed with a corrugated thread like surface, substantially
as herein described, and in reference to and shown in the accompanying Sheet of
Drawings.
In witness whereof, I, the said Friedrich Hermann Felix Engel, have hereunto
set my hand and seal, this Fourteenth day of January, in the year of our
Lord One thousand eight hundred and eighty two.