An experimental investigation was performed evaluating the performance of two types of abrasive cutting jets (aspirated and suspension jets) in chambers that simulated ocean depths to 6100 m. Test cuts were made on stainless-steel specimens at nozzle pressures up to 379 MPa and at different standoff distances. For ambient pressures between 17 and 69 MPa, the suspension jet cutting performance is not highly dependent on the ambient pressure, but a significant performance loss occurs in going from 0 to 17 MPa. This phenomenon is attributed to jet cavitation effects. The abrasive jet, particularly the suspension jet, shows promise for development into a valuable tool for underwater cutting applications.
Traditional rock and metal cutting methods for underwater applications have serious technical, safety, and environmental limitations. Cutting methods for deployment via remotely operated vehicles (ROVs) in ocean depths to 6000 m with ambient pressures to 69 MPa are needed for exploration, mining, and salvage operations. High-pressure waterjets and abrasive-waterjets (AWJs) offer feasible solutions to many underwater applications. Specialized waterjet-based tooling has been developed to provide solutions to a range of underwater applications. High-energy-waterjet pulse generator systems can be used to replace chemical explosives in regulated underwater applications (Kollé, 1993). Waterjet systems have been designed for utilization on ROV s to cut underwater cable trenches for oceancrossing utility cables (Adamson and Kolle, 1996). AWJs have been used to cut steel structures in offshore repair and decommissioning operations (Surle, 1990); other related studies addressing underwater AWJ cutting include Domann and Aust (1990) and Haferkamp et al. (1990). High-pressure intensifier pumping systems have also been developed for operation at full ocean depths (Kirkwood and Steele, 1994). AWJ technology was introduced commercially in 1983. Since then, substantial advances have been made in our basic understanding of the cutting process and in the associated hardware. New applications in drilling, turning, and milling are constantly emerging.