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Explosion relief valve test tank |
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|  MIL-E-23457B(SHIPS)
used, the entire receiver structure, covers, etc. which would be subject to the pressure of
an air receiver explosion shall withstand a gage pressure at least 5 lb/in2 above the
pressure at which the relief valve is fully opened.
3.7.5.5 In addition to meeting all the requirements in 3.7.5.1 through 3.7.5.4, the
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crankcase and air receiver explosion valves shall include a flame arresting device which
will contain or stop the emission of flame and burning oil through the valve in the event
of an explosion. The valve design shall include blast deflectors which will direct explo-
sion forces away from personnel who might be standing along side the engine. The lift
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area of the valve when open shall be at least twice the area of the valve seat in in .
When tested in accordance with 4.4.2.12, the complete explosion valve with flame arresting
device shall be subjected to at least three successive test explosions without loss of
effectiveness and with no replacement of any valve assembly components or parts permitted
between explosions. There shall be no evidence or egression of flame or burning oil.
The valve tank shall include as a minimum
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3.7.5.6 Explosion relief valve test tank.
the
following
features:
(a) An ignition system capable of igniting the explosive mixture and continue
ignition after the explosion until the tank is purged and filled with fresh
air.
(b) Provisions to introduce an oil mist Society of Automotive Engineers ((SAE) 30
lubricating oil) heated to 150F prior to, during, and after each explosion.
(c) Heating devices to maintain an internal tank temperature of 150F to 200F.
(d) Fan or other means of creating turbulence and thoroughly mixing the air/gas/
oil mist mixture prior to the explosion.
(e) Vents to admit fresh air to purge the tank after the explosion.
(f) Instrumentation to measure the air/gas mixture in the tank prior to explosion.
(g) Instrumentation to measure and plot an explosion time/pressure curve to
determine that valve opening, closing, and pressures developed are within
the requirements of 3.7.5.2, 3.7.5.4 and 3.7.5.5.
(h) Photographic equipment to record the valve action and particularly the
egress of flame or burning oil during explosion should it occur.
3.7.6 Welding. Welding and allied processes shall be in accordance with MIL-STD-278
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unlessspecific waiver have been or are granted by NAVSEC.
3.8 Fluid piping systems.
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3.8.1 Piping.
Engine attached piping shall be strapped and supported by the engine
structure to prevent vibration and reist shock. Take-down joints in fuel systems shall be
kept to a minimum to reduce leaks. 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 discharge)
shall be in accordance with MIL-STD-777. Flange connections shall be either commercial or
Navy type. If commercial flanges are supplied, each connection to ships piping systems
shall be provided with a companion flange for welding to ships piping. Navy flanges for
steel or nonferrous piping and fittings shall conform to MIL-F-20042 or MIL-F-20670, as
applicable. Except as exempt (see 3.8.1.1), 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.
Taper pipe threads are permitted in the following areas:
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3.8.1.1
Pipe plugs in sizes of 3/4 inch and below used for applications where design
(a)
gage pressures do not exceed 50 lb/in2. Plugs shall be seal welded or
brazed, if possible.
(b)
Instrumentation, controls, vent, filling, and drain connections where design
gage pressures do not exceed 50 lb/in2 and where fluids handled:
(1)
are not toxic.
(2)
are not dangerous.
(3)
would not cause atmospheric contamination.
(4)
would not create a fire hazard, and which would not cause, in the event
of failure, a major breakdown of equipment nor create a hazard to the
surrounding area nor affect the operation of other vital equipment.
(c)
Pipe plugs internal to the engine.
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