METHOD AND APPARATUS FOR NON-OXIDIZING TREATMENT OF ELONGATE PIPES Russian patent published in 2002 - IPC

FIELD: metallurgy, nuclear engineering, heat engineering and engine manufacture. SUBSTANCE: method involves drawing pipes through process conveyance channel filled with inert gas and defined by intensified heating and cooling zones with several intermediate movable supports, wherein each pipe is sequentially directed at constant speed through slight heating zone, through zone for heating pipe to temperature exceeding recrystallization temperature, holding zone, cooling zone and additional cooling zone, with pipe temperature in slight heating zone and in additional cooling zone not exceeding 500-800 C and time of passage through holding zone being within 5-100 s. While passing through heating, holding and cooling zones, pipe is subjected to axially symmetric heating and cooling procedures, with these zones being positioned between supports. Pipe internal cavity is continuously purged with shielding gas at flow rate preventing air from flowing in while pipe conveyance speed being limited. Shielding gas flows through process channel in direction opposite to that of pipe and is discharged therefrom in front of heating zone. Prior to feeding pipe into process channel, plugs are located at pipe ends and removed upon completion of thermal treatment procedure. At additional cooling zone, outer surface of pipe is purged with traverse flow of cooled shielding gas at pressure exceeding atmospheric pressure, with following straightening of pipe. While passing through heating zone pipes are arranged in abutting relation one with respect to another. Apparatus has module designed for forced feeding of pipes to conveyance channel and equipped with sealing device and gate, rollers, heating and holding unit, refrigerator with water cooled casing, additional cooling refrigerator, discharging rollers, output sealing unit with gate, and module for forced discharge of pipes from channel. EFFECT: increased efficiency in thermal treatment of high-precision pipes manufactured from fireproof and corrosion resistant chromium-nickel steel and alloys. 11 cl, 6 dwg