BRAZING HANDBOOK 1 Forewords The CuproBraze brazing handbook is a way to share the latest knowledge regarding the CuproBraze process. It deals with technical questions in general. The CuproBraze process is rather young and developments in different areas are still on-going. Therefore, all recommendations in the handbook should be seen as advice, sometimes better or other ways to success can be found. The handbook will be updated from time to time and if there are any questions or other matters which should be included, please contact editors. The handbook is based on the original manuscript of Leif Tapper, who has retired when this edition comes out. Editor-in-chief: Markku Ainali Co-editors: Anders Falkenö, Robbie Robinson Contact and feedback to
[email protected] Edition Nr 8, September 2006 Västerås, Sweden 2 Contents 1. General 1.1 1.2 1.3 1.4 Efficient heat exchangers Technology development Effects of annealing Soldering and brazing 2. Copper alloys 2.1 2.2 2.3 2.4 Fin material Tube material Brass material for headers, side supports and similar applications Strength at elevated temperatures 3. Filler materials 3.1 3.2 3.3 Brazing powder Brazing foil Brazing paste 4. Paste application 4.1 4.2 4.3 Paste on tubes Paste on fin tips Tube-to-header joints 5. Fabrication and assembly of components 5.1 5.2 5.3 5.4 5.5 Tube fabrication HF-welded tubes Folded tubes Fins Headers 3 5.6 5.7 Surface conditions Brazing fixtures and assemblies 6. Brazing operation 6.1 6.2 Atmosphere Temperature and time 7. Selecting a furnace 7.1 7.2 7.3 7.4 7.5 Batch furnace Semi-continuous furnace Continuous furnace Heating source Process emissions 8. Corrosion resistance 8.1 8.2 8.3 8.4 Cleaning after brazing lnternal corrosion External corrosion Coatings 9. Special brazing processes 9.1 9.2 9.3 9.4 One shot brazing Brazing of parts with internal turbulators (CAC) Splitter fin together with CuproBraze Brazing of steel parts 10 Quality check 10.1 10.2 10.3 Visual inspection in general Visual inspection of the tube-fin joints Cross sections of the joints 4 11. Reparability 11.1 11.2 11.3 Soldering Re-brazing Brazing with AgCu filler metals 12. Troubleshooting 13. Luvata Brazing Center 14. Getting started 14.1 14.2 14.3 14.4 Contacts Web sites Regular publications Recent technical literature 15. CuproBraze in brief 5 6 1. General New brass and copper alloys offer high strength as well as excellent retention of strength at elevated operating temperatures. They can withstand high-temperature brazing processes without substantial loss in strength. A Brazing Center has been established to build prototype heat exchangers based on these new alloys and to demonstrate the CuproBraze® process. As a result, CuproBraze® technology is now being applied globally in the manufacture of advanced heat exchangers using the new brazing process described in this manual. B