MIL-STD-2193 Ship Hydraulic System ComponentsThis standard provides design, construction, and testing requirements that are common to most components used in ship hydraulic power transmission and control systems. This standard does not establish configuration requirements, pressure, flow, or performance requirements for any specific component.

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MIL-STD-2193C(SH)

5.2.9.1  Threaded inserts.  Tapped holes larger than 6.4 millimeters (mm) (0.25 inch) diameter in nonferrous parts to be used for mounting screws or bolts shall incorporate inserts conforming to NASM8846, MIL-I-45910, or MIL-I-45932.  For high shear strength materials (above 345 MPa, 50,000 lb/in2), inserts are not required when adequacy of design is verified by calculations in accordance with FED-STD-H28.  The insert specifications provide guidance on determining the length of insert required.  As a minimum, the insert length selected shall not result in shear tear out in the parent or tapped material if the fastener is tightened to 135 percent of the torque value indicated on the component drawing.

5.2.9.2  Bolt hole diameter.  Hole diameters for mounting bolts shall not exceed those diameters produced using standard size drills as identified in table V.

TABLE V.  Bolt hole diameters.

5.2.9.3  Safety.  Hand-adjustable threaded parts subject to tampering shall be securely locked by safety wiring, self-locking nuts, or other methods specified in the component specification.  Safety wire shall be applied in accordance with NASM33540 and shall conform to NASM20995.  Star washers, lock washers, and jam nuts shall not be used as locking devices, except that jam nuts may be used on function-adjustment screws as specified in

5.2.12.

5.2.9.4  Self-locking devices.  Self-locking nuts used with through-bolting shall be in accordance with NASM25027.  Externally threaded self-locking elements shall be in accordance with MIL-DTL-18240.  For component internal fastenings which require disassembly of the component to retighten, loosening shall be prevented by self-locking nuts or self-locking externally threaded fasteners.

5.2.9.5  Washers.  Washers shall be used, as necessary, to provide load distribution, a hardened bearing surface, locking assistance, or some combination of these functions.  Washer material shall be compatible with the

assembled parts.  Selection of washers shall be in accordance with SAE-J2655.

5.2.10  Retainer rings.  Retainer rings or snap rings shall not be used unless the requirements of 5.2.10.1 through 5.2.10.3 are met.

5.2.10.1  Load limitation.  Hydraulic, structural, mechanical, or any other form of loads, or combinations thereof, including vibration, shock loads, expansion, or contraction due to thermal changes, and so forth, which may cause axial displacement or failure of the ring, shall not be exerted on the ring.

5.2.10.2  Installation clearances and tolerances.  Retainer rings or snap rings shall not be used where buildup of clearances and manufacturing tolerances will allow destructive end play in the assembly that may cause, or contribute to, failure of packings or gaskets brinelling, or fatigue failure of parts.

5.2.10.3  Installation and removal.  The retainer rings or snap rings shall be installed and removed with standard pin-type pliers or other standard tools developed for use with the rings.

5.2.11  Spring pins.  Unless approved by the contracting activity, spring pins shall not be used in any applications that conflict with NASM33547.

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