12) and rotated as they pass through the furnace, the tubes (18, 19), when heated in the furnace (10, 11, 12), are kept apart by pushing each tube (18, 19) into the furnace at one end with a pusher (24, 25, 26) and pulling it out from the other end with a puller (30-...
12) and rotated as they pass through the furnace, the tubes (18, 19), when heated in the furnace (10, 11, 12), are kept apart by pushing each tube (18, 19) into the furnace at one end with a pusher (24, 25, 26) and pulling it out from the other end with a puller (30-...