Steel-Tubular Electrode Cutting Technique (cast iron and non-ferrous metals).
Cast iron and non-ferrous metals do not oxidize; therefore, underwater cutting essentially becomes a melting process. There is no chemical reaction of the oxygen and the base metal. Therefore, the only benefit realized by the oxygen is the mechanical effect of blowing the molten metal away. Since the melting process takes place only in the immediate vicinity of the arc, the following procedure is recommended:
- Using a sawing motion, manipulate the electrode in and out of the cut.
- For thin plates, electrode manipulation is not necessary since the procedure is virtually the same as when cutting thin, ferrous metal.
- Maximum current (up to 500 amperes if available and provided the safety switch is rated to carry such a load) is recommended since the cutting is dependent upon the melting action of the arc.
After each use, rinse the torch in fresh water and dry it. Disassemble and inspect the flashback arrestor for corrosion damage due to electrolysis or clogging.(Frequent clogging or screen burn-out indicates either insufficient oxygen pressure or burning the electrode shorter than the 3-inch minimum.) Replace any damaged parts. All equipment should be thoroughly dry before storing. Secure hose ends with caps or tape to keep out debris. Store all equipment, including electrodes, in an oil-free environment. Electrodes which have been exposed to salt water will rust. They should be rinsed with fresh water, blown dry and stored separately to prevent damage to other rods.