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|  MIL-D-18641F(SH)
g. Submergence pressure boundary studs and bolts shall be of a reduced shank design to
reduce bending stresses.
3.14.281.1.5.1 Inspection openings. Threaded fasteners securing water box inspection openings
in submarine distilling plant heat exchangers subjected to submergence pressure shall be designed
such that 200 inspection cover removal and reinstallation cycles and the cycles specified in
3.14.28.1.1.4.1, will not cause the maximum cumulative usage factor to exceed 0.8. The effect on
threaded fastener stress levels caused by any movement between the inspection rover and
inspection cover flange when the seawater side of the water box is pressurized shall be specifically
analyzed. The amount of movement or relative slip used in above analysis shall be confirmed
during factory hydrostatic testing of first unit (see 4.3.1.1). The measured amount of relative slip
shall be compared to the assumed value. The fastener shall meet the requirements of ASME
Boiler and Pressure Vessel Code, section III, division 1, subsection NB, class 1 components when
the measured slip (rather than the assumed slip) is factored into the analysis.
3.14.28.1.1.6 Operation. Distillation units for submarines shall operate at an ambient pressure
of 30 inches of Hg absolute with a variable of plus or minus 6 inches Hg and shall not be damaged
z
when subjected to an ambient absolute pressure between 10 and 30 lb/in with the minimum
internal pressure which will prevail under any condition of operation.
3.14928,2 Shutdown. Distilling units on saturated steam propelled surface ships and submarines
shall accommodate a one-button shutdown of the unit which will safely secure all steam, sea water
feed and brine dilution, trip all solenoid operated dump valves and secure all distilling plant pumps.
The one-button shutdown system will be provided by the shipbuilder.
3.14.283 Heating steam circuit For distilling units on saturated steam propelled surface ships,
the heating steam circuit of the salt water feed heater shall be vented to atmosphere only. The
vent piping shall contain an orifice sized for normal operation. A bypass with globe valve shall be
provided around the orifice for use during start up.
3.14.29 Acid cleaning connections. Connections, with hose-gate valves, complete with chain
and cap shall be provided in the integral piping of the unit, if feasible, or in shipbuilder furnished
external piping, for introduction, circulation and discharge of acid solution for chemically cleaning
the distilling unit. Type II units shall have the feedwater piping so arranged that reducing flanges
with 1 inch nominal pipe size nipples (to be furnished with the unit) may be installed to permit
the salt water heater, the air ejector after condenser and the stage condensers to be individually
chemically cleaned
.
3.1430 Piping. Integral piping, valves, fittings and similar items shall be in accordance with
MIL-STD-777 or MIL-STD-438 as applicable Seawater feed control valves for Types II and IV
distilling plants shall be in accordance with MIL-V-18030 or Drawing 803-1385S41 except that valve
body, seat and disc material shall be nickel copper alloy.
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