MIL-PRF-2863C(SH)
concentration of water-leachable sulfur in the material shall be
determined as follows:
Sulfur µg/g (ppm) = C multiplied by 500/M
where:
C
=
sulfur concentration of filtrate, in milligrams per liter; and
M
=
grams of test specimen, prepared per a) above.
4.4.2.3 Cadmium and lead concentration. Any standard test method may be used
to determine total cadmium and lead concentration (suggested: use oxygen
combustion bomb digestions for metal analysis; analyze digestates of cadmium
and lead by direct aspiration atomic absorption spectroscopy).
4.4.3
Simulated performance.
4.4.3.1 Test fixture. Simulated performance tests shall be conducted in an
apparatus consisting of two 1.25-inch thick brass tube sheets bolted to the
flanged ends of an 11-inch length of 8-inch pipe. Each tube sheet shall
contain six stuffing boxes drilled 0.75 inch deep and tapped for 0.625-inch
condenser tubes. Ferrules are to be 0.625 inch long with 18 threads per inch.
Copper nickel alloy tubes of 0.049-inch wall thickness shall be used in the
test. Thermocouples shall be located in the center of each tube sheet and
inside the pipe. In the event that sustained leakage occurs, provisions shall
be made to collect leakage water from the joints for volumetric measurements.
4.4.3.1.1 Test samples. Only packing assemblies that have been tested per
paragraphs 3.3, 3.4 and 3.5 of this procedure shall be used for simulated
performance tests. Each packing assembly and its location in the test fixture
shall be recorded. This will allow identification of a particular packing
assembly's physical characteristics in the event that there is leakage.
4.4.3.1.2 Grade A. The six tubes shall be packed with four rings at each
end. The four-ring installation shall consist of two metallic and two non-
metallic rings. Screw ferrules shall not be used. The order of installation
shall be: first a non-metallic ring installed at the bottom of the stuffing
box followed by a metallic ring, then the second non-metallic ring and the
second metallic ring last.
4.4.3.1.3 Grade B. The six tubes shall be packed with three rings at each
end. The three-ring installation shall consist of two metal rings and one
non-metallic ring. The order of installation shall be: first a metallic ring
installed at the bottom of the stuffing box followed by the second metallic
ring and last, the non-metallic ring installed next to the screw ferrules.
Ferrules are to be 0.625 inch long with 18 threads per inch.
4.4.3.2 Conditions. The performance of the packing in maintaining watertight
tube-sheet end stuffing boxes shall be determined under the following
successive conditions:
a) Water at 10 psi and 70°F for half an hour for initial tightness.
b) Water at 50 psi, 200°F for grade A and 300 psi, 200°F for grade B
maintained for 5 hours.
c) Condenser tubes moved ten times alternately forward and backward 1/8
inch while condition b) is maintained. Tube movement is accomplished
by light blows of a one-pound hammer on a guide pin inserted in the
end of the tube.
d) Condenser drained and vented for two weeks.
7
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