MIL-DTL-24630A(SH)
3.3.5 Recycled, recovered, environmentally preferable, or biobased materials. Recycled, recovered,
environmentally preferable, or biobased materials should be used to the maximum extent possible, provided that the
material meets or exceeds the operational and maintenance requirements, and promotes economically advantageous
life cycle costs.
3.4 Design and construction.
3.4.1 External. The valve design, construction, and overall valve body dimensions shall be as specified herein
and on the applicable specification sheet (see 3.1).
3.4.2 Internal. Internal design and construction shall incorporate the reliability and maintainability
requirements specified in 3.4.3. Valve design shall offer the least practicable restriction to the flow of hydraulic or
lubricating oil fluids such that the pressure drop requirements specified in 3.5.3 are met. Internal parts shall be
accurately guided to prevent misalignment, surging, or chattering on the seat at rated flow capacities with the valve
axis in any position. The valve seat shall be of adequate strength to withstand high flow velocities up to
40 feet per second and pressure transients up to 4,000 lb/in², which can be associated with hydraulic systems
pressurized to a maximum operating pressure of 3,000 lb/in². Internal parts shall be sized such that these parts will
not pass through the valve waterway. Destructive methods such as peening or staking for retaining internal parts
shall not be used.
3.4.3 Reliability and maintainability.
3.4.3.1 Reliability. The valve shall demonstrate 50,000 mean cycles between failure (MCBF) during testing as
specified in 4.6.6.
3.4.3.2 Maintainability. The mean time to repair (MTTR) of the valve shall not exceed 30 minutes. The
MTTR is to be limited to fault isolation and repair by parts replacement. Internal parts shall permit easy
disassembly and reassembly and shall prevent incorrect reassembly of parts. Individual valve parts shall be self-
aligning and shall be non-reversible unless such parts, when reversed, do not alter function or performance.
3.4.4 Special tools. The design shall be such that special tools will not be required for normal maintenance and
inspection of the valve (see 6.5.2).
3.4.5 Threads. Threads shall be of the type specified on the applicable specification sheet and shall be in
accordance with FED-STD-H28. Pipe threads shall not be used. Where required to prevent galling, valve body
connecting threads shall be lubricated with grease conforming to MIL-PRF-27617, Type I, prior to assembly of the
valve.
3.4.6 Sizes. Valves shall conform to sizes shown on the applicable specification sheet.
3.4.7 Fluid compatibility. Unless otherwise specified (see 6.2), the valve shall be constructed of materials that
are compatible with fluids as specified in MIL-PRF-17331, MIL-H-19457, MIL-PRF-17672, MIL-H-22072,
MIL-PRF-6083, MIL-PRF-83282, and MIL-DTL-17111.
3.4.8 O-rings and seal lubricants. O-rings and seals shall be lubricated with grease in accordance with
MIL-PRF-27617, Type III, prior to assembly of the valve.
3.4.9 Surface finishes. Burrs shall be removed and sharp edges shall be broken to a radius of 0.005 inch
minimum. Unless otherwise specified (see 3.1), surface roughness shall not exceed 125 microinches. Surface
roughness shall be in accordance with ASME B46.1.
3.4.10 O-ring glands. O-ring glands for new designs shall be in accordance with SAE-AS4716. O-ring glands
that conform to MIL-G-5514 are permitted for use in existing valve designs.
3.5 Performance.
3.5.1 Maximum operating pressure. The valve shall function at a maximum operating pressure of 3,000 lb/in²
(see 4.6.1).
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