METHOD OF FIXING TUBES IN TUBE PLATES Russian patent published in 2001 - IPC

FIELD: treatment of metals by pressure. SUBSTANCE: method may be used for fixing of tubes with bimetallic profiled ends in tube plates of heat-exchange apparatus. Bushing made of plating material with activated external surface is preliminarily press-fitted in tube hole. Circular projections of trapezoidal cross-section are formed on external surfaces of tube ends. In this case, zones of mechanical seizing are formed on contact surface of bushing and tube. Tube is installed in tube hole of tube plate provided with circular grooves of rectangular cross-section. Circular projections of tube are combined with circular grooves of tube plate, and tube is fixed to prevent its displacement. Then tube is secured in tube plate hole by application of compressing force to its internal surface. When fixing the tube, plating material of bushing and plated material of tube are subjected to cold welding first of all along circular surfaces located on reverse side of circular projections. EFFECT: enhanced strength, density and corrosion resistance of joints. 6 dwg