METHOD OF FASTENING TUBES IN TUBE PLATES Russian patent published in 2003 - IPC

FIELD: plastic metal working; possibly, fastening of tubes in tube plates of heat-exchange apparatuses with usage of localized direct plastic deformation of tube material. SUBSTANCE: tube ends are shaped with formation of tips having load-carrying and support portions and intermediate conic portion located in between. In tube hole on its face side provision is made for a circular gap and combined annular groove in the form of combination of annular grooves of rectangular and triangular cross-sections. On outside surface of load-carrying portion of tube on side of its end a thicker part is provided which diameter is equal to diameter of support portion. This thicker part is connected with outside surface of loadcarrying portion by means of conic reducer. Distance between edges of circular gap and annular groove of tube hole is larger than distance between small bases of intermediate conic portion of tip and conic reducer of its thicker part. One of the tips is placed in tube hole with conic surfaces located opposite these edges of tube hole. Tube is fixed preventing possible motion and fastened in tube hole by means of applying compressive force to inside surface of load-carrying portion of tip. EFFECT: enhanced service characteristics of obtained connections owing to formation of ring seals on interperpendicular surfaces of tube hole. 6 dwg