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|  MIL-E-23457B(SHIPS)
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3.8.2.2.2 Construction. Coolers shall be capable of withstanding a hydrostatic gage
pressure of 115 lb/in2 on both the cooled and cooling side. Vent and drain connections
shall be provided to permit complete venting and draining of both sides. Supports shall
be provided for securing to a foundation. Coolers shall not be supported by plates or
brackets in such a manner that the primary means of support is obtained from the bolts
securing the shell end flange-tube sheet-water box flange joints.
3.8.2.2.2.1 Tubes. Coolers shall have straight tubes. Coiled or U-tubes are not
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permitted. Tubes shall be 1/4-inch outside diameter (o.d.) by 0.022-inch thick wall (24BWG)
or 3/8-inch o.d. by 0.028-inch thick wall (22BWG). The minimum pitch for 1\4-inch tubes
shall be 5/16-inch and 29/64-inch for 3/8-inch tubes.
3.8.2.2.2.2 Tube joint. Tubes shall be either roller expanded into the tube sheets or
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attached to the tube sheets by silver-brazing. When roller expanded, the minimum effective
depth of expansion shall be one tube diameter. Provision shall be made for the support of
the tubes and prevention of tube vibration.
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3.8.2.2.2.3 Cooling surface. The amount of cooling surface installed in all coolers
shall be based on the service (specified in 3.8.2.3, 3.8.2.4 and 3.8.4.2) applying a 10
percent fouling factor to the heat transfer coefficient for clean tubes.
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3.8.2.3 Heat exchangers. Fresh water/sea water heat exchangers shall be sea water
cooled and shall be in accordance with 3.8.2.2. The use of heat exchanger cores installed
in expansion tanks or other enclosed areas in the cooling system is permitted provided the
core construction and materials meet the requirements of 3.8.2.2.
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3.8.2.4 Intercoolers When used, intercoolers (aftercoolers) shall be sea water cooled
and shall be in accordance with 3.8.2.2. The use of intercooler cores installed in intake
manifolds or other enclosed areas of the air intake system is permitted provided the core
construction and materials meet the requirements of 3.8.2.2.
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3.8.2.5 Water temperature control. Temperature regulator valves and thermostatic
valves shall be either the fail-safe type which shall pass all the cooling water through
the cooler in the event of failure of the thermostatic element or be provided with a manual
"over-ride" for the thermostatic element.
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3.8.2.6 Inhibitors. Engines shall be capable of operating using coolant inhibitors
conforming to O-S-588 (chromate type) , MIL-I-24453 (non-toxic soluble oil type) , and
0-1-490 (compatible with ethylene glycol antifreezes).
3.8.2.7 Gasket and packing. Gaskets and packing used in the cooling system shall
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be of material resistant to deterioration by sea water or when any of the following are
added to the fresh water system:
(a) Antifreeze compounds conforming to O-A-548.
(b) Corrosion inhibitor compounds conforming to O-S-588, MIL-I-24453, or
0-1-490.
(c) Preservative compounds conforming to MIL-C-16173 and MIL-L-21260.
3.8.3 Fuel system. Engines shall be capable of operating on fuel corresponding to
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both JP-5 of MIL-T-5624 and diesel fuel of MIL-F-16884. The fuel system shall include the
following:
Positive displacement type fuel pump.
(a)
(b)
Relief valve connected to discharge into pump suction or supply tank.
Priming pump.
(c)
Filters.
(d)
(e)
Necessary piping, valves, and fittings.
3.8.3.1 If leak-off from the injectors and fuel pump exceeds 2 percent of the supply
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pump capacity, necessary equipment shall be provided to automatically return leak-off fuel
to the service tank.
3.8.3.2 Fuel pump. The engine driven positive displacement fuel pump shall have a
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suction lift capility of 48 inches.
3.8.3.3 Filtration. The fuel system shall be protected by a primary filter (strainer)
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ahead of the engine mounted fuel pump and a duplex secondary filter ahead of the fuel
injection pump or unit injectors. If the fuel system is of such a design that the filter
must be positioned on the suction side of the fuel pump, only the secondary filter is
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