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|  MIL-V-19069B
pressure during the pressure buildup portion of each cycle shall be 150 + 5
percent of the rated pressure. Surge pressure in the free-flow direction
shall be between 125 and 150 percent of the rated pressure. The rated flow
capacity shall be as indicated in table IV.
4.5.9.1 High temperature cycling. The valve 0shall be subjected to
12,500 cycles of operation at a temperature of 275 F. Upon completion of
these 12,500 cycles, the valve shall be soaked at a temperature of 275F for a
period of one hour with the rated pressure applied to the valve in the
reverse-flow direction. The pressure shall then be relieved to approximately
zero, and the valve soaked for an additional one hour at a temperature of
0
275 F. The temperature shall then be reduced to the 70 to 1200F range, and
the operational inspections (checking time and cracking pressure) shall be
conducted, and the requirements therein shall be satisfied. The temperature
0
shall then be lowered to not higher than -65 F. When the temperature of the
test specimen has been stabilized, the operational inspections shall be con-
ducted, and the requirements therein shall be satisfied.
4.5.9.2 Intermediate temperature cycling. After completing the high
temperature cycling `inspection, the valve shall be subjected to 37,500 cycles
of operation at a temperature of 225F. Upon completion of these 37,500
cycles, the high temperature functioning inspection shall be conducted at a
0
temperature of 225 F, and the requirements therein shall be satisfied. The
0
0
temperature shall then be reduced to the 70 to 120 F range and the fluid
temperature stabilized at 100F. The leakage inspection shall then be con-
ducted and the requirements therein shall be satisfied.
4.5.10 Burst pressure. This inspection shall be performed at a tempera-
ture of 275F and any suitable fluid may be used. Hydraulic pressure shall be
applied in the free-flow direction, with the outlet port plugged, at a rate of
approximately 25,000 psi per minute, until a pressure of 7500 psi is ob-
tained. The valve shall withstand this burst pressure for a period of two
minutes without rupture of internal or external parts.
4.6 Quality conformance inspection. Each check valve to be furnished
under this specification shall be examined to determine conformance with
material and design requirements and shall be subjected to the following tests
described under "Quality conformance inspection methods":
a.
Examination of product
b.
Proof pressure
c.
Leakage
d.
Cracking pressure
4.7 Quality conformance inspection methods.
4.7.1 Examination of product. Each valve shall be carefully examined to
determine conformance with the requirements of this specification with regard
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