Abstract: A heat treating furnace in which an electrical resistance heating element is disposed in a chamber and is energized by way of a power feed through conductor which extends slidably through the wall of the furnace. An insulating washer and a retaining washer may be installed on and removed from the inner end portion of the feed through conductor from inside the furnace without either removing the conductor from the furnace wall or disconnecting the conductor from the heating element. A power terminal block and inlet and outlet lines for cooling water are adapted to be quickly and easily disconnected from the outer end portion of the feed through conductor to permit the conductor to be easily pulled inwardly through the furnace wall for servicing.

Abstract: A nozzle for delivering cooling gas into the work chamber of a heat treating furnace. The nozzle is formed by a resiliently yieldable metal tube having an overlapping seam and adapted to be contracted radially for insertion through a hole in the wall of the work chamber. After being inserted through the hole, the tube springs outwardly into frictional engagement with the edge of the hole to retain itself in place. Flares on the ends of the tube prevent the tube from shifting endwise relative to the chamber wall.

Abstract: A heat treating furnace having a work chamber of circular cross-section and having banks of electric resistance heating elements formed by rigid and elongated graphite bars. The graphite bars of each bank are interconnected so as to form an octagon located closely adjacent the circular wall of the work chamber and closely approximating the circular shape of the chamber. As a result of the octagonal arrangement, ring-like banks of rigid graphite elements may be space longitudinally along the circular work chamber to enable front-to-rear temperature trim zones to be established in the chamber.