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: An upwardly pyramidal frame, formed of angularly spaced legs converging to a point, is mountable on a holder that extends about a fill opening of the pressure tank of a blast cleaning system. The frame is so disposed as to break open the end of a bag containing an abrasive media, when the bag is dropped onto the frame, with the break occurring at a location confined to the area of the fill opening. A screen supported upon a shoulder of the holder extends across the opening. At the bottom of the frame, outwardly directed feet on the legs extend into a space between the shoulder on which the screen is supported, and opposing, downwardly facing shoulders. Screws threaded in the feet bear against the peripheral portion of the screen, to clampably engage the feet and the screen against the opposed shoulders. When a screen is to be replaced, the screws are backed off, to loosen the frame and screen and permit their removal and replacement.

Abstract: A valve for controlling flow of abrasive media from a blast tank to a nozzle, utilizes rollers for constricting a straight-through tube. In this way the valve meters the flow of the abrasive media into a blast hose through which air is directed under pressure as a carrier for the media. Contact with the media within the valve is limited to a radially constrictable tube adapted for ready replacement as the only component subject to the destructive characteristics of media such as mineral grit, sand, or the like. In association with the pinch tube housing, means is provided permitting ready interchange of manual and automatic tube-constricting assemblies. In the automatic configuration, the size of the valve orifice through which the media passes can be accurately and swiftly regulated by varying the pressure on a diaphragm.

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.