Materials Used In Underwater Shielded Metal Arc Welding

Equipment used for shielded metal arc welding is discussed in Chapter 4. Consumable materials required for shielded metal arc welding consist of commercially produced waterproofed wet welding electrodes. Table 3-2 lists the preferred electrodes identified during wet welding screening and certification tests conducted by the Navy.

3-6.1 Underwater Shielded Metal Arc Welding Electrodes. Commercial manufacturers have made significant progress in the development of waterproofing systems for wet welding electrodes. Details of these systems are proprietary to each manufacturer; however, the results of their cumulative efforts have produced a new generation of wet welding electrodes. Certain electrodes mentioned in Table 3-2 are manipulative types for use in all positions. With the correct welding procedures and equipment, weld deposits display excellent bead appearance and improved mechanical properties.

Table 3-3 depicts recommended welding currents and arc voltages to be used as a starting point for wet welding to depths up to 50 FSW.

3-6.2 Tong Test Ammeter. The tong test ammeter (Figure 4-9) is a portable instrument that will quickly measure current flowing in a circuit without making electrical connections to it. It is a most important tool use while setting-up for and during electric underwater cutting and welding operations. The tong test ammeter is discussed in greater detail in Chapter 4.

3-6.3 Electrode Polarity. Wet welding is usually conducted using STRAIGHT POLARITY, sometimes referred to as DC ELECTRODE NEGATIVE, which results in longer life of the electrode holder. While straight polarity, electrode negative is the traditional method, this is by no means a hard and fast rule. Occasionally, more successful results may be obtained using reverse polarity, DC ELECTRODE POSITIVE. Some typical applications for reverse polarity include the following:

S0300-BB-MAN-010 Table 3-2. Electrodes for Underwater Shielded Metal-Arc Welding Size Description Specification

Commercially Prepared Waterproof Electrodes

1/8" Andersen Easy1 Carbon Steel -

1/8" BROCO Carbon Steel --

Sof-Touch1 (E7014)

1/8" BROCO SS Stainless Steel --

1. These electrodes have passed Navy qualification testing; larger sizes are available, but have not yet been tested by the Navy.

Table 3-3. Recommended Amperage Settings for Wet Welding to Depths of 50 Feet

Electrode

Welding Position

Type

Size

Horizontal

Vertical

Overhead

Arc1

inch

Amps

Amps

Amps

Voltage

E7014

1/8

140-150

140-150

130-145

25-35

5/32

170-200

170-200

170-190

26-36

3/16

190-240

190-240

190-230

28-38

E3XX

1/8

130-140

135-140

125-135

22-30

1. Arc voltage, also referred to as closed-circuit voltage, is the voltage recorded by the voltmeter as welding is in progress. Tong meter amperage reading should also be recorded as welding is in progress.

1. Arc voltage, also referred to as closed-circuit voltage, is the voltage recorded by the voltmeter as welding is in progress. Tong meter amperage reading should also be recorded as welding is in progress.

a. Manufacturer's recommendations, particularly for stainless steel electrodes.

b. Improved running characteristics of the electrode.

c. Control of weld bead shape and penetration.

d. Altered magnetic fields to reduce magnetic arc blow. 3-7 UNDERWATER WELDING ARCS

The welding arc does not behave underwater as it does on the surface and the activity of the gas bubble is particularly important to successful completion of the underwater weld. When the arc is struck, the combustion of the electrode and the detachment of water creates a gas bubble or envelope, as illustrated in Figure 3-2. As the pressure within the bubble increases, it is forced to leave the arc and meet with the surrounding water while another bubble forms to take its place. Then, as this pressure head becomes greater than the capillary force, the bubble breaks down. Therefore, if the electrode is too far from the work, the weld will be destroyed as the gases explode and blow through. If the travel speed is too slow, the bubble will collapse around the weld and destroy the possibility of producing an effective weld.

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