Abstract: Apparatus for blast-cleaning the interior surface of a pipe includes a main housing that travels the length of the pipe, and rotatably supports a blast nozzle. A nozzle support shaft carried by the housing rotates freely, reactively to air carrying abrasive media and forced through the nozzle under high pressure. Since the air is directed through a non-rotating conduit to the shaft, a gasket is interposed between the rotating and non-rotating components. To prevent the abrasive media from penetrating the shaft support bearings of the housing with obviously destructive effects, a gap is maintained between the housing and a junction housing in which the non-rotating conduit is mounted. Leakage that does occur past the gasket is dispersed to the ambient atmosphere through the gap, before it can impinge upon the bearings. The non-rotating conduit is threadedly advanceable within the junction housing, so as to correspondingly, selectively adjust the extent to which the gasket is compressed.

Abstract: A blast cabinet having at least one cabinet door opening into the blast chamber includes a pneumatic interlock between the door and a valve through which air is supplied under pressure to a gun within the chamber. The valve is actuated to an open position by air under pressure admitted under the control of an operator. Incorporated in the tubing system through which the air under pressure is directed to the valve is a header which is left in communication with ambient air whenever the door is open, to depressurize the supply of air to the valve and thus prevent it from opening under these conditions.