Underwater Oxygen Arc Cutting Torches

Underwater oxygen arc cutting torches are designed for gripping the cutting electrodes and for delivering power to the electrode and oxygen to the electrode bore. Safety is a primary consideration in their design and construction. All current-carrying parts of the torches must be fully insulated to afford full protection to the diver from electric shock and to protect the torch from rapid corrosion due to electrolysis. The torches also should be lightweight, simple in construction, easy to maintain and should incorporate an electrode clamping

Figure 4-10. Voltage Drop in Welding Cables.

device which will make the changing electrodes underwater a relatively simple task. Only torches which have been designed specifically for underwater cutting shall be used. The torches must also have a sufficient capacity for the maximum current required by the electrodes with which the torch is to be used. The elements of an oxygen arc cutting torch are:

a. Collet or grip which holds tubular cutting electrodes and provides for entry of oxygen into the cutting electrode bore.

b. Oxygen valve for controlling oxygen flow rate.

c. Electrical connector for attaching a power cable.

d. Flash arrester to prevent hot metal particles from entering the torch. Never, under any circumstances, operate a cutting torch without the flash arrester and monel screen.

e. Insulated coupling between the electrode and the oxygen valve to safeguard the operator from electric shock and to prevent damage of the valve due to electrolysis.

f. Complete insulation for all current-carrying metal parts of the torch to safeguard the operator against electric shock and to protect the metal parts from deterioration by electrolysis.

The diver can check a particular torch or electrode holder for electrical integrity by calling for "switch on," with the electrode not in contact with the work-piece. Bubbles due to electrolysis should arise only from the electrode tip. Bubbles occurring elsewhere indicate current leakage from the torch or electrode holder itself.

Figures 2-6a, b and c illustrates the elements of three torches specifically designed for underwater oxygen-arc cutting.

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