Tube-in-shell heat exchangers
AssigneeNational Nuclear Corporation Limited
InventorOwen Hayden
Life of this patent
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Abstract
A method of repairing a defective tube in a tube-in-shell heat exchanger which entails inserting within the defective tube a tubular sleeve and sealingly bonding the end regions of the sleeve to the tube to bridge the defect, the tubular sleeve having axial flexibility (for example by being circumferentially corrugated). The sleeve may be mechanically keyed to the tube at positions adjacent to the bonding at the end regions of the sleeve.
Claims19
A method of repairing a defective tube in a tube sheet of a tube-in-shell heat exchanger, which method comprises inserting within the defective tube a tubular sleeve, and sealingly bonding spaced end regions of the sleeve to the tube sheet and the tube to bridge the defect, wherein, the improvement comprises an unbonded portion of the tubular sleeve defining a plurality of circumferential corrugations lying between the bonded end regions so as to possess axial flexibility.
A method of repairing a defective tube in a tube sheet of a tube-in-shell heat exchanger, which method comprises inserting within the defective tube a tubular metal sleeve, and sealingly bonding spaced end regions of the sleeve to the tube to bridge the defect, wherein the improvement comprises,
- (a) cleaning regions of the tube and of the tube-sheet by an electro-erosion technique, said regions being opposite to where the end regions of the sleeve are to locate therein;
- (b) cutting relatively small circumferential grooves in the tube and the tube sheet inboard of and adjacent to where the end regions of the sleeve are to locate;
- (c) inserting through the tube sheet and the tube a metal sleeve having a plurality of circumferential corrugations therearound;
- said corrugations being formed inwardly of the end regions so as to locate in the tube between the tube sheet and the grooves in the tube, and the sleeve having braze material thereon;
- (d) expanding the end region of the sleeve remote from the tube sheet to define a capillary clearance between the tube;
- (e) heating by an induction heating coil the said remote end of the sleeve, so as to effect a brazed joint thereat;
- (f) forming an explosion welded joint between the tube sheet and the adjacent end region of the sleeve;
- (g) and expanding the sleeve into the grooves at the regions of the grooves in the tube sheet and the tube, so as to mechanically key the sleeve to the tube sheet and to the tube.
Dependencies are inferred from the claim text.