The rotating joint housing is placed over the fluid passage tube. The bearing, formed by two sealed casings, is mounted on the shaft of the rotating joint housing via upper and lower clips. The rotating joint housing and the outer wall of the fluid passage tube are fitted with matching internal threads and external threads, respectively. A locking nut is threaded onto the external thread of the fluid passage tube at the top of the rotating joint housing, securing it in one position on the tube. The skeleton sealing sleeve is inserted into the fluid passage tube. A layer of oil film provides lubrication and sealing. When air and liquid abrasive rise to the liquid surface, the air layer is compressed, impeding the ascent of the liquid abrasive along the outer wall of the fluid passage tube.