_Steam Pipes_.--The failures of copper steam pipes on board the Elbe,
Lahn, and other vessels have drawn serious attention both to the
material and to the modes of construction of the pipes. The want of
elastic strength in copper is an important element in the matter; and
the three following remedies have been proposed, while still retaining
copper as the material. First, in view of the fact that in the operation
of brazing the copper may be seriously injured, to use solid drawn
tubes. This appears fairly to meet the main dangers incidental to
brazing; but as solid drawn pipes of over 7 inches diameter are
difficult to procure, it hardly meets the case sufficiently. Secondly,
to use electrically deposited tubes. At first much was promised in this
direction; but up to the present time it can hardly be regarded as more
than in the experimental stage. Thirdly, to use the ordinary brazed or
solid drawn tubes, and to re-enforce them by serving with steel cord or
steel or copper wire. This has been tried, and found to answer
perfectly. For economical reasons, as well as for insuring the minimum
of torsion to the material during manufacture, it is important to make
as few bends as possible; but in practice much less difficulty has been
experienced in serving bent pipes in a machine than would have been
expected. Discarding copper, it has been proposed to substitute steel or
iron. In the early days of the higher pressures, Mr. Alexander Taylor
adopted wrought iron for steam pipes. One fitted in the Claremont in
February, 1882, was recently removed from the vessel for experimental
purposes, and was reported upon by Mr. Magnus Sandison in a paper read
before the Northeast Coast Institution of Engineers and Shipbuilders.[2]
The following is a summary of the facts. The pipe was 5 inches external
diameter, and 0.375 inch thick. It was lap welded in the works of
Messrs. A. & J. Stewart. The flanges were screwed on and brazed
externally. The pipe was not lagged or protected in any manner. After
eight and a half years' service the metal measured where cut 0.32 and
0.375 inch in thickness, showing that the wasting during that time had
been very slight. The interior surface of the tube exhibited no signs of
pitting or corrosion. It was covered by a thin crust of black oxide, the
maximum thickness of which did not exceed 1/32 inch. Where the deposit
was thickest it was curiously striated by the action of the steam. On
the scale being removed, the original bloom on the surface of the metal
was exposed. It would thus appear that the danger from corrosion of iron
steam pipes is not borne out in their actual use; and hence so much of
the way is cleared for a stronger and more reliable material than
copper. So far the source of danger seems to be in the weld, which would
be inadmissible in larger pipes; but there is no reason why these should
not be lapped and riveted. There seems, however, a more promising way
out of the difficulty in the Mannesmann steel tubes which are now being
"spun" out of solid bars, so as to form weldless tubes.
[Footnote 2: Transactions Northeast Coast Institution of Engineers and
Shipbuilders, vol. 7, 1890-91, p. 179.]