Investigating the Impact of Brazing on Heat Exchanger Process Fluid Contamination

Brazing is a joining process where two materials (metals or ceramics) are joined with a lower melting point filler metal. Brazing provides very strong and precise joints without melting the materials being joined. Brazing is being considered as an alternative method to create heat-exchangers; however, it is not known if the filler metal will cause additional impurities in the process fluid. This research explores the contingencies of nickel brazing when brazed joints are exposed to high-temperature solutions (80⁰C) for extended times. Our methods involve; soaking brazed 316L stainless steel samples, un-brazed Stainless Steel, “316” and GTAW (gas tungsten arc welding) stainless steel in three separate solutions; WFI (water for injection), CIP-100 (clean in place, alkine) and CIP-200 (clean in place, acidic) for a range of time periods to metal concentration changes within the process solutions. Furthermore, the effect of the brazing process on the stainless steels being joined will be assessed through electrochemical testing to compare corrosion performance before and after the braze heating cycle. This research will help to determine whether brazing is acceptable for manufacturing heat exchangers for use in heated, ultra-high purity water.