MIL-DTL-23953 Valves, Combined Vent-Check, For Submarine Mbt Blow Lines \(Sizes 2.00 And 2.50 Inches\)This specification covers the construction, testing, and operation of combined vent-check valves with a nominal pressure seating of 4,500 pounds per square inch gage \(psig\), for use in submarine main ballast tank \(MBT\) high-pressure air blow lines \(sizes 2.00 and 2.50 inches\).

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MIL-DTL-23953D(SH)

3.4.1 Recycled, recovered, or environmentally preferable material. Recycled, recovered, or environmentally

preferable material should be used to the maximum extent possible, provided that the material meets or exceeds the

operational and maintenance requirements, and promotes economically advantageous life cycle costs.

3.5 Construction requirements. Detailed construction and assembly requirements shall be as specified in

803-8436621.

3.5.1 End preparation. End preparation shall be as specified in table I.

TABLE I. End preparations.

Assembly

Valve size

End preparation

Joint design

(see 6.2)

(inches)

Socket weld

P-14 of MIL-STD-22

2�

Butt weld

P-74 of MIL-STD-22

Union end

Designed to mate with

union tailpieces in

accordance with

803-1385884

3.5.2 Boundary parts. The proof and burst pressures for pressure boundary parts shall be as specified in

table II.

TABLE II. Proof and burst pressures.

Nominal rating

Proof pressure

Burst pressure

(minimum)

(psig)

4,500

6,750

13,500

3.5.3 Body construction. Valve bodies for Assemblies A and B shall be machined from a one-piece casting.

Valve bodies for Assembly C shall be machined from a one-piece casting or forging. Inlet and outlet ports shall be

in-line.

3.5.3.1 Surface cast valves. The surface of cast valve bodies and guides shall be free from cracks, tears, laps,

shrinkage, inclusions, gas holes, and other harmful or injurious defects. Any shrinkage, dross, porosity, inclusions,

or chaplets in the interior of cast valve bodies and guides shall be within allowable levels for nonferrous castings per

S9074-AR-GIB-010/278.

3.6 Performance requirements.

3.6.1 Check feature flow capacity. Required capacity in this specification is in terms of blow down time for a

25 cubic foot (ft�) pressurized reservoir. When installed as specified in 4.4.11, the vent-check valve shall dump

pressure from 1,500 psig to 500 psig in times not exceeding those specified in table III.

TABLE III. Capacity requirements.

Assembly

Maximum allowable blow

down time (seconds)

6.3

5.1

5.0