This invention pertains to the field of cutting and gouging metals submerged in a non-volatile liquid. The largest field of use of the present invention is in the electric-arc cutting and gouging of metallic objects submerged under large bodies of water such as rivers, lakes, oceans and the like. Such objects can be sunken vessels, submerged portions of floating vessels such as ships, barges and the like, fixed submerged structures such as bridge pilings, coffer dams, piers, or other submerged structural objects. In recent years, electric-arc cutting is being used extensively for the construction and maintenance of offshore oil and gas drilling platforms.
The conventional electric-arc cutting processes used under water are detailed in U.S. Pat. Nos. 2,396,307; 2,417,650; 2,462,463; and 3,751,625. All of these patents disclose in detail underwater cutting torches which employ the well-known oxy-arc process. In the conventional oxy-arc process an electric-arc is struck between a hollow electrode and the workpiece. Simultaneously, oxygen gas is forced down through the center bore of the electrode to provide the chemical reaction in the cutting process. Such processes are limited to through cutting of metals.
In the area of underwater construction and salvage it is sometimes desirable to remove only a portion of the surface of a metallic object in preparation for underwater welding. U.S. Pat. No. 2,706,236 discloses the well-known air-carbon arc cutting and gouging process which for many years has been used on dry land for preparing metal objects for welding. The air-carbon arc cutting and gouging process employs a carbon (graphite) electrode to establish an arc between the electrode and the workpiece to heat and melt the portion workpiece under the arc. Simultaneously, a stream of compressed air is forced down along the electrode to forcibly remove the molten metal from the influence of the arc and from the workpiece thus enabling a skilled operator to gouge the metal for subsequent filler metal welding.
With the conventional oxy-arc process it is not possible to provide for gouging of metallic workpieces submerged in an aqueous environment.
USPTO Backgrounds
USPTO Backgrounds