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|  MIL-G-24477(SHIPS)
3.2.4.2 Gaurds and shields. Guards and shields shall be furnished as specified in
3.2.4.2.1 and 3.4.2.2.
3.2.4.1 Gaurds. Guards for protection of personnel shall be provided for flywheels
and other exposed moving parts. Where there are no feasible means for attaching the guard
to the equipment, the guards will be furnished by the engine builder and the installing
activity will accomplish the installation.
3.2.4.2. Shields. All hot machinery surfaces shall be shielded or insulated so that
no external surface the machinery shall exceed a temperature of 400F. All fuel and
lubricating oil lines or fittings, including gage lines, shall be located or shielded so
that any leaks cannot drip or spray on any component with a surface temperature of 400F.
or higher.
3.2.4.3 Crankcase fumes. The engine builder shall provide a system to dissipate
through the engine intake or exhaust system all oil fumes generated by the engine in the
crankcase and other areas.
3.2.4.4 Engine crankcase and air box explosion protective devices or design. All
diesel engines with cyclinder bore diameter of inches or greater shall protected from
the hazard of crankcase or air receiver explosions by one of the procedures specified in
3.2.4.4.1 through 3.2.4.4.5.
3.2.4.4.1 If the crankcase can be demonstrated by test to withstand an internal gas
pressure of 100 pounds per square inch gage (psig) without rupture, it is considered to be
acceptably safe to contain a crankcase explosion and no other protection devices is required.
For the purpose of this demonstration, the term crankcase shall be interpreted to include
the entire engine structure that would be exposed to internal gas pressure in the event of
a crankcase explosion.
3.2.4.4.2 If the integrity of the engine crankcase and related volume cannot be demon-
strated as specified in 3.2,4.4,1, the engine shall be provided with spring loaded explosion
relief valves in each cylinder crankpit, to provide a total relief area of at least 1-1/2
square inches, for each cubic foot of total crankcase volume. These relief valves shall be
designed to be fully open at a crankcase pressure of 20 psig, and to close and seal the
crankcase from air when the pressure has been relieved. The entire crankcase system in the
terms of 3.2.4.4.1, including any access covers, shall be designed to withstand an internal
pressure of at least 25 psig without failure when explosion protection devices are used.
3.2.4.4.3 The air receivers of two cycle engines (only) of 6 inch diameter or larger
cylinder sizes, shall also be protected from air receiver explosions. If the air receivers,
including all associated structure that would be subject to gas pressure in event of air
explosion, can be demonstrated to withstand 125 psig internal gas pressure, no other air
receiver explosion protection device is required.
3.2.4.4.4 If the pressure integrity requirements of 3.2.4.4 cannot be met, the air
receiver shall be provided with an explosion relief valve or valves, having at least 1-1/2
square inches of relief area per cubic foot of total air receiver system volume. These
relief valves shall be designed to be tight at maximum air receiver operating pressure and
to be fully open at 20 psig pressure above that operating pressure level. The valves shall
be designed to relieve the explosion and reset tightly. When these explosion relief valves
are used, the entire receiver structure, covers, etc., which would be subject to the pressure
of an air receiver explosion shall be designed to withstand at least 5 psig above the pres-
sure at which the relief valve is fully opened.
3.2.4.4.5 Explosion relief valve design requirement. All crackcase or air box explo-
sion relief valve, if used, shall be provided with blast deflectors which will direct
explosion forces away from personnel who might be alongside the machinery.
3.2.4.5 Welding. Welding and allied processes shall be in accordance with MIL-STD-278.
3.2.5 Fluid piping systems.
3.2.5.1 Piping. Engine attached piping shall be strapped and supported by the engine
structure to prevent vibration and resist shock. Takedown joints in fuel systems shall be
kept to a minimum to reduce leaks. All connections from the engine to the ship's systems
(i.e. exhaust, lubricating and fuel oil inlet and return, and the raw water supply and dis-
charge) shall be in accordance with MIL-STD-438. Flange connections shall be Navy type.
Navy flanges for steel or nonferrous piping and fittings shall conform to MIL-F-20670 or
MIL-F-20042, as applicable. Except as exempted in 3.2.5.1.1, taper pipe threads are not
permitted in engine piping systems, accessories or driven equipment. Thread connections,
where used, shall employ straight threads in accordance with MS16142.
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