Abstract: A pipe spin-blast tool having a tubular handle with inflow and outflow ends. An inner pipe is rotatably mounted to the tubular handle and a jet head is fixed at the end of the inner pipe for rotation therewith. A sand-air mixture is caused to enter the inner pipe through the inflow end of the tubular handle, whereafter the mixture exits the pipe sand-blast tool through angularly aimed nozzles on the jet head. A stationary annular disc and a rotating annular disc are disposed between the jet head and the tubular handle coaxial to the inner pipe. The stationary disc is fixedly mounted to the outflow end of the tubular handle and includes a first set of permanent magnets having coinciding poles aligned parallel with the inner pipe. The rotating disc is mounted to the inner pipe so that it will rotate relative to the stationary disc and has a second set of permanent magnets having coinciding poles oriented opposite the poles of the first set.

Abstract: An improved spin-blast tool having a stationary handle with coaxial inner and outer pipes. The inner pipe, connected to a jet head, rotates at high speed relative to the stationary outer pipe. A plenum defined by the outer surface of the inner pipe and the inner surface of the outer pipe, as well as by opposed lateral sealed bearings, supporting the inner pipe within the outer pipe, define a plenum which is filled with a viscous fluid. The inner pipe supports radially outwardly extending vanes which work against the viscous fluid, thereby slowing rotation and preventing damage to the inner shaft and the jet head. An axial groove along the outer peripheral surface of the inner pipe leaks small amounts of the viscous fluid beneath at least one of the sealed bearings for the purpose of lubricating a stationary shaft seal which comes in contact with rotating members.