MIL-DTL-24630A(SH)
c. For those sizes selected for full qualification testing, the inspections shown in table II shall be
accomplished.
d. For those sizes selected for similarity qualification, the tests specified in 4.6.1, 4.6.2, 4.6.4.1, and 4.6.4.2
shall be accomplished. Only a single specimen is required for these tests, and the adverse tolerance requirements of
4.2.1.1 Minimum clearance specimen. One specimen shall be assembled from parts which have been selected
to provide that the clearance with regard to linear and diametrical tolerances between moving and non-moving
members, conducive to malfunctioning at extreme temperatures, will not exceed 110 percent of the minimum
designed clearance permitted by the manufacturer s drawings. For cases of sliding parts where packing friction
would influence the performance of the component, such as pistons operated by spring, the maximum packing
friction anticipated shall be induced in the test specimen. In these cases, O-ring packing glands shall be fabricated to
provide maximum design O-ring squeeze, including the effect of adverse O-ring cross-section tolerances. This
specimen shall be marked "MIN."
4.2.1.2 Tolerance considerations. In machining these specimens, surface finishes shall be of no finer degree
than the surface finishes as will be produced on production units. Where friction is not a factor, packing glands may
be fabricated to nominal dimensions. Lapped or selectively fitted parts may be fabricated to nominal dimensions.
In order to fabricate specimens with adverse tolerance, it is permissible for one of the mating parts required to
produce the critical clearance to be outside of drawing tolerances, provided that the clearance, as fabricated, falls
within the range specified. In the event that the design clearances in themselves are extremely close, the 10 percent
limitations on clearance may be adjusted or waived entirely, but at the discretion of NAVSEA. In case of waiver of
adverse tolerance specimens, tests shall be conducted on two representative production samples, and the test report
shall analyze the effects of adverse tolerance conditions.
4.3 Conformance inspection. Conformance inspection shall include the examination of 4.5 and the tests of 4.6
through 4.6.11. Each valve in the contract quantity shall be subjected to the inspection. Any valve which fails to
conform to the inspection shall be rejected.
4.4 Test conditions.
4.4.1 Temperature. Unless otherwise specified herein, the tests shall be conducted at room temperature of
59 to 86 °F (15 to 30 °C).
4.4.2 Test fluid and fluid temperature. Unless otherwise specified herein, the fluid used for pressure drop tests
shall be in accordance with MIL-PRF-17331 and shall be maintained at a temperature at which the actual fluid
viscosity is 100 centistokes (cSt). This temperature shall be maintained to ±35.6 °F (±2 °C). Viscosity data used to
determine test temperature (approximately 100.4 °F [38 °C]) should be recorded.
4.4.3 Positioning. Unless otherwise specified (see 6.2), tests may be conducted with the valve axis in either of
the following positions:
a.
Horizontal.
b.
Vertical (the force of gravity acting opposite to the checking action).
4.5 Examination.
4.5.1 Visual and mechanical examination.
4.5.1.1 External. Each valve shall be subjected to an external visual and dimensional examination to determine
conformance with the requirements of this specification, applicable specification sheets, and manufacturer s
drawings.
4.5.1.2 Internal. Each valve shall be disassembled and shall be subjected to a visual and dimensional
examination to determine conformance with the requirements of this specification, applicable specification sheets,
and manufacturer s drawings.
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