Underwater Cutting Tools
- Underwater cutting tools are used for cutting steel, concrete, wood and other materials for ship salvage, wreck removal and harbor clearance and require specially trained operators. Some systems function by remote operation and computer assistance while others require a skilled diver and an above-water crew. Most cutting systems require a cutting torch.
- The deepwater chop saw is a remote cutting tool that has a rotating blade which cuts underwater pipes, cables and solid bar stock. An attached clamp holds the work piece in place while the saw blade passes through the workpiece.
- When attached to torches, cutting rods, which burn to more than 10,000 degrees Fahrenheit, melt or cut practically any known material. Some can bend to 90 degrees for difficult-to-reach places. Standard length for these cutting rods is 18 inches, but for heavier jobs that require more burn time, 36-inch rods are available. Rods come in either 1/4-inch or 3/8-inch diameters.
- Many underwater cutting systems involve the use of a cutting torch. Plasma arc-cutting or PAC is the process where a constricted arc of plasma composed of ionized gas is used to sever metal by melting a small area of the workpiece. For underwater arc-cutting, the torch and the workpiece are submerged in three inches of water. Often used for cutting non-ferrous metals, an air plasma torch implements a tungsten electrode with an electric arc and is also used in a shallow- water bath. The water bath minimizes noise, ultraviolet radiation and fumes while it lessens thermal distortion of the workpiece. Another torch, used in deep underwater arc-cutting, is part of an electric arc-oxygen system. This torch has a collet which holds the fully insulated, steel-covered waterproofed tubular electrode. In this system, the arc is produced normally and the oxygen is supplied through a tube exiting center hole of the electrode.
Oxyfuel is fuel used in special cutting torches that contains oxygen. Oxyacetylene is used in cutting torches up to 25-feet depths; any depth greater than 25 feet requires hydrogen gas and a oxyhydrogen cutting torch because greater pressure is required to make cuts in greater depths.
The Oxypetrol system supplies the oxygen-gas cutting torch with liquid gasoline and then combines the gas with oxygen to preheat the steel. When the steel under the torch nozzle reaches the proper temperature, an oxygen valve is opened and the jet of oxygen cuts the steel. - Exothermic cutting requires a Direct Current welder, with underwater exothermic cutting rods. The process involves communication between the diver and the above-water support crew. The power is controlled by the support crew and is initiated at the request of the diver.
- The wood boring air drill bores through wood in marine timbers among other underwater uses. Wood boring drill bits are available from 1/2-inch diameter to 1-1/8 inch diameter with 12-inch to 36-inch lengths.