HNSA Crest with photos of visitors at the ships.

6A1. Introduction. The submarine is provided with a salvage air system for use in salvage operations.

The salvage air arrangements provide external salvage facilities for use by outside salvage agencies (divers, etc.) as well as internal facilities for use by the crew of the submarine or by a diver who succeeds in entering the vessel.

Figure 6-1 shows in schematic form the location and relation of the component parts which comprise the salvage air system.

Two external high-pressure air connections, located on each side of the conning

Figure 6-2. Main ballast tank salvage connection.
Figure 6-2. Main ballast tank salvage connection.

  tower, provide a means of supplying high-pressure air from the salvage ship to the high-pressure (3000-pound) receiving manifold. This air can be directed by personnel inside the vessel to the 600-pound blow manifold for use in blowing the main ballast tanks, and to the 225-pound service air manifold for use in blowing water from flooded compartments by means of the compartment salvage air valves.

Each main ballast tank has a blow valve with a blow line connection extending up to a plate set in the deck (Figure 6-2). In salvaging, air hose lines from the salvage ship are attached to the pipe fitting. Opening the valve enables the rescue vessel to blow the ballast tanks free of water.

Figure 6-3. Compartment salvage connection.
Figure 6-3. Compartment salvage connection.


6A2. Salvage valves. Each compartment of the submarine has two salvage valves, one at each end of the compartment. A salvage line from each valve extends through the hull to a deck plate (Figure 6-3), where it is provided with a capped male fitting similar to those of the main ballast tank salvage lines (Figure 6-2). The valve (Figure 6-3) can be operated by a socket wrench from the outside or by a handwheel from within the compartment. In salvaging operations, air hoses can be attached to the valve fittings to supply the ship with air for breathing, pumping, or circulating purposes.

All the external salvage valve deck plates are identified by lettering and round screw

  heads and special lugs cast on the plates for touch identification. (See Section 6C.)

Compartment salvage air valves are located on each bulkhead between compartments (Figure 4-1) for use in blowing individual compartments. The 225-pound air is supplied to these compartment salvage air valves by lines extending from the forward and after ship's service air lines. (See Section 4A.) The arrangement of the valves permits the release of air from either side of the bulkhead into the adjacent compartment. Pressure gages are installed on both sides of the bulkhead near this valve arrangement to indicate the pressure in the adjoining compartment.

6B1. Description. This section describes those air salvage operations conducted from within the submarine, either by the vessel's crew or by a diver who has succeeded in entering the submarine.

The air which is used can come either from the ship's air banks or from the salvage ship by way of the high-pressure air external charging connections.

The main ballast tanks can be blown from within the submarine by directing air from the 3000-pound to the 600-pound MBT blow manifold and from there to the tanks. The procedure followed in blowing the main ballast tanks is the same as outlined in Chapter 3, provided, of course, that none of the blow lines has been broken or the tanks ruptured.

Each compartment of the vessel is provided with a compartment salvage air valve, located high on each transverse bulkhead. (See Figure 4-1.) Two hundred and twenty-five-pound air is supplied to each valve by a branch line from the forward or after service air main, depending upon the location, as outlined in the previous article.

Each salvage valve is provided with two outlets and two controlling handwheels. It

  is mounted on the bulkhead with one outlet and one handwheel on each side of the bulkhead to permit the blowing of any flooded compartment from the adjoining compartment.

6B2. Operation. To illustrate the general procedure to be followed in blowing a flooded compartment using the compartment salvage air valves, assume that it is desired to remove water from the after battery compartment, working from the control room. In the control room, the salvage air valve on the after bulkhead is opened by turning the handwheel counterclockwise. This admits air into the after battery compartment. (Clockwise rotation of this handwheel would admit air into the control room.) The adjacent pressure gages will indicate the air pressure in the battery compartment. When the pressure necessary to keep the compartment free of water is indicated, the valve handwheel should be returned to the neutral position. By building up an equal pressure in the control room, the door between the compartments can be opened without dropping the pressure in the battery compartment.

Detailed instructions for salvaging flooded compartments are given in Chapter 11.


6C1. Description. Each main ballast tank is provided with a salvage valve and a salvage line for use in external salvage operations. Each valve is fitted with a square-ended extension stem, reaching to the main deck, where a deck plate (Figure 6-2) is located to receive it. The receiving end of the salvage line is fitted with a threaded connection and a protecting cap with projecting lugs for easy unscrewing. This connection is fitted in the same deck plate as the valve stem. The valve stem is operated by a socket wrench. The deck plates are located off the centerline.

In use, the air hose from the salvage ship is connected by a diver to the salvage line and the salvage valve opened, thus admitting air to the tank and blowing it free of water. Each tank must be blown separately.

Each compartment has one salvage valve and one salvage line located at each end of the compartment. These valves and lines have deck fittings similar to those of the main ballast tanks, but located as near the centerline as possible. The valve body is located between the pressure hull and the superstructure deck, with one end of the stem extending up to the deck plate (Figure 6-3) and the other end of the stem projecting through the pressure hull. The inboard end of the stem is fitted with a handwheel containing a luminous button. Thus these valves can be operated from within the vessel or from the outside.

In each compartment, one valve, termed the high connection, supplies air near the high point of the hull. The other valve, termed

  the low connection, is equipped with a pipe extending to the low point of the compartment. The low connection pipe is equipped with a strainer to protect the system from clogging.

To circulate air from the outside throughout a given compartment, the, diver must connect one air hose to the high connection and another to the low connection. With pressure applied to the hose connected to the high connection, its valve is opened, allowing air to enter the compartment. Opening the low connection valve allows the air to escape.

When blowing out the compartment, both the high and low connections are opened. Compressed air entering the compartment through the high connection forces the water into the low-connection pipe and thus overboard.

The external salvage connections for the main ballast tanks are tested hydrostatically to a pressure of 15 psi. The external compartment salvage connections are tested hydrostatically to a pressure of 300 psi.

All the external hose connections (deck plates) are identified by lettering; special markings are provided to enable the diver to identify the plates by touch. These markings are lugs, or screws, cast or attached to the deck plates. The tables on page 40, list the markings used on a typical submarine. The actual arrangement of the markings for any individual submarine is shown on the vessel's air salvage system plans.


Officers' quarters12
Forward torpedo and control room34
Crew's quarters56
Forward engine room78
After engine room910
Maneuvering room1112
After torpedo room1314

MBT Nos. 2A and 2B1
MBT No. 12
MBT Nos. 2C and 2D2
MBT Nos. 6A and 6B3
MBT Nos. 6C and 6D4
MBT No. 75

MBT Nos. 2A and 2B2
MBT Nos. 2C and 2D4
MBT Nos. 6A and 6B8
MBT Nos. 6C and 6D10

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