Underwater CuttingUnderwater cutting is a process that has undergone considerable change over recent years. It is used for cutting steels at depths of up to 35 metres, although equipment is available for deep-water cutting. Oxygen-acetylene can be used at depth of up to about 8 metres and oxygen-hydrogen are normally used at greater depths. The underwater cutting torch resembles a normal hand cutting torch. The preheat flame is created in the normal way and the oxygen cutting stream is initiated once the steel has reached ignition temperature. The water is held back from the flame with a jet of compressed air fed through an outer nozzle on the torch. The flame is either passed down to the working area already lit or a low current spark can be struck between the torch nozzle and a striker plate. Underwater cutting is more frequently carried out today using an oxygen arc or thermic cutting process where an electric arc is struck between the hollow electrode or packed lance and the work. High pressure oxygen is fed through the electrode or lance to melt and burn away the steel or other material.
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