Roofinox® stainless steel is readily solderable with suitable tools. The surfaces to be joined must be free of grease, dirt or other foreign matter. Dirt makes soldering difficult and must be removed before work begins. By observing the following points, you will achieve an outstanding solder quality.
For Roofinox and Roofinox tin-plated fluxes based on phosphoric acid are suitable. Not suitable are fluxes based on hydrochloric acid or dilute hydrochloric acid or containing chloride ions. The industry offers a range of soldering fluxes suitable for stainless steel. Best results are achieved with Roofinox FLM.
Roofinox FLM guarantees sufficient removal of the thin passive layer and prevent its renewed formation during soldering. They provide optimal wetting and cleanliness of the soldering area. If the soldered joint will be subjected to particular stress, please contact us. Conducting a solder test is recommended before beginning the job to ensure that the desired result will be achieved. Residues of flux absolutely have to be removed. We recommend cleaning the soldering joint area with fresh water.
For Roofinox and Roofinox tin-plated tin/lead alloys are generally used. The tin potion may range from 30% to 50%. The solder may not contain more than 0.5% antimony. These solders, in conjunction with the Roofinox FLM flux, provide optimal gap filling, good wetting and high strengths. With the required soldering temperature of approximately 250ºC, the melting range of this solder is well suited to guarantee good flow characteristics.
Soldering irons with a minimum weight of .77lb assure sufficient heat storage, a weight of 1lb and higher is better suitable. The broad bearing surface (.2’’) of the soldering iron is important to assure even heat transfer onto the soldering joint. This quality is guaranteed with the appropriate care of the soldering iron.
According to professional regulations soldering joints should be overlapping .4’’ to .6’’. Larger overlapping is not recommended as it can’t be soldered properly and flux will remain in the overlap. This residue in combination with water will leak from the overlap and can discolor or cause streaking on the surface.
The optimal soldering gap width is approximately .0012’’. This enables maximum gap filling through capillary filling pressure. The soldering gap must not expand in the flow direction. It must be constant or narrow slightly.
Joins on gutters, attachment joins etc. are subjected to stronger mechanical stress, therefore a mechanical join (rivet) is necessary. In this instance, solder has predominantly a sealing function. We recommend stainless steel rivets or Roofinox tin-plated stainless steel rivets that facilitate soldering.
Roofinox provides low thermal ductility, this demands a lower soldering temperature and sectional working. This should prevent overheating of the soldering area and thus preventing the solder from solidifying. More details can be found in our information sheet Soldering.