| (a) Process.-
The copper shall be fire-refined or electrolytic and shall be
made into tubes either by the hot rolling or cold drawing process.
The tubes shall be finished by cold drawing.
(b) Chemical Composition.- To comply with Regulation
(c) Freedom from Defects.- The finished tubes, both
externally and internally shall be sound, clean, smooth, well
finished and free from surface defects and longitudinal grooving,
and the ends must be clean and square.
(d) Tolerance.- The actual weight of each tube shall
not be more than 5% above the calculated weight. Unless, otherwise
specified, they shall be straight cylindrical, of uniform
thickness and external diameter throughout.
(e) Tensile Tests.- Tensile tests shall be made on
pieces of tubes or strips cut from the tube. If the tensile
test is made on a piece of tube, the ultimate tensile stress
shall be not less than 14.50 tons (32,480 lbs.) per sq. inch
with an elongation of not less than 50 per cent on 2 inches.
If the tensile test is made on strip cut from the tube, the
ultimate tensile stress shall be not less than 14 tons (31,360
lbs.) per sq. inch with an elongation of not less than 40
per cent on a test piece having a gauge length of four times
the square root of the area.
The results obtained from a batch shall be uniform, and should
a variation of more than one ton (2,240 lbs.) per sq. inch
be found between any number of tubes tested, the batch shall
be liable to rejection. A batch shall not consist of more
than 500 tubes.
(f) Bulging or Drifting Test.- The test piece shall
stand bulging or drifting cold (see Diagrams 1 and
without showing either crack or flaw, until, the outside diameter
of the bulged or drifted end measures not less than 25 per
cent more than the original diameter of the tube.
(g) Flanging Test.- The test piece shall stand flanging
cold (see Diagram 3) without showing either crack or flaw
until the diameter of the flange measures not less than 40
per cent more than the original diameter of the tube.
(h) Flattening and Doubling over Test.- The test piece
shall stand the following test, both cold and at a red heat,
without showing either crack or flaw. The test piece shall
be flattened down until the interior surfaces of the tube
meet and then be doubled over on itself, that is bend through
an angle of 180° (see Diagram
4) the bend being at right
angles to the direction of the length of the tube.
|Hydraulic Test. - Each tube shall be tested, before
the tubes are presented for inspection by an internal
hydraulic pressure of 750 lbs. per sq. inch or by such
internal hydraulic pressure as may have been specified
by the Inspecting Authority and the Inspector may re-test
5 per cent or more as he may deem necessary.
The tubes shall withstand the test without showing any signs
of weeping or any evidence of defects.
(j) Treatment of Test Specimens.- All test material,
if not already in an annealed condition, shall be annealed
before testing and shall comply with the mechanical tests
without further heat or mechanical treatment.