MIL-S-21520C
(Wep)
3.3.2
Hydrostatic
Pressure
3.3.2.1
Steady Pressure - The intertube seals shall
withstand a hydrostatic pressure of 195 to 205 psig for
100 hours, shall show no leakage, and thereafter shall be
capable of meeting all performance requirements of this
specification except that the 100 hours shall not be in
addition to the requirement specified in 3.3.2.3.
3.3.2.2
Rapidly Applied Pressure - The upper inter-
tube seals shall withstand a hydrostatic pressure increased
from 30 to 130 ± 5 psig within 0.5 to 0.7 seconds, main-
tained for 15 seconds, applied 25 times, shall show no
leakage, and thereafter shall be capable of meeting-all
performance requirements of this specification,
3.3.2.3
Pressure Cycling - The intertube seals shall
withstand 50 cycles of hydrostatic pressure. A cycle
shall consist of raising the pressure from 0 psig to 195
to 205 psig, maintaining the pressure for 2 hours, and then
reducing the pressure to 0 psig for 2 hours. After cycling
the seals shall show no damage and shall be capable of meet-
ing all performance requirements of this specification
except the 50 cycles shall not be in addition to the re-
quirement specified in 3.3.2.1.
Flexure - The intertube seals shall withstand
3.3.3
300 cycles of flexure at the rate of 1 cycle-per-minute
and thereafter shall be capable of meeting all performance
requirements of this specification. A cycle of flexure
shall consist of moving the inner circumference of the seal,
relative to the periphery through an 8 by 12 inch ellipt-
ical path with the major axis of the ellipse perpendicular
to the diameter of the seal.
3.4
Environmental
Conditions
3.4.1
High Temperature - The intertube seals shall
withstand exposure to air at a temperature of +110 ± 4
degrees Fahrenheit with a relative humidity of 95 to 98
percent for 12 hours, shall show no damage, and thereafter
shall be capable of meeting all performance requirements
of this specification.
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