Method and apparatus for replacing a flue sig liquid volume by a corresponding volume of gas, which is immersed in a space enclosed

摘要

A tool for underwater welding comprises an open-mouthed bell with an axially extending electrode inside, part of that electrode being surrounded by a tube supplying gas under pressure from a pumping station floating on the surface. Another tube linking the bell with that pumping station supplies water under pressure to an annular chamber open toward an array of fluid-guiding blades carried by the bell. In one embodiment, the bell is rotatably mounted and carries the blades on its outer surface, being set in rotation by the oncoming flow; in another embodiment, the bell is stationary and the blades are arranged on its inner surface whereby the water swirls in a film along that surface. In either case the circulating water forms a vortex that passes along the bell periphery and around the bell mouth which is slightly spaced from the workpiece to be welded, the resulting centrifugal forces preventing the entry of surrounding water into the bell whereby a gaseous atmosphere is maintained in its interior.