Many attempts have used stainless steel pipes for indoor and outdoor water supply pipes. If it is possible to use stainless steel pipes for water supply pipes, the problem of water pollution harmful to the human body is found to be eliminated in traditional galvanized steel pipes and copper pipes. In addition, because stainless steel pipes are rigid and superior in corrosion resistance, they can be embedded in a concrete floor. The traditional copper pipe must be processed on the floor surface to occupy space in the room. Since thedegradion of stainless steel pipes is less in their service than PVC pipes, they basically do not leak or break due to freezing water in winter.
Stainless steel is composed of a special oxide film, which contains chromium. The oxide film is thin and insoluble and the special flow is required to completely dissolve the oxide film in a soldering operation. However, the magnetic flux residue of such magnetic flux is an inherently corrosive base metal, that is, stainless steel.
Therefore, it is unusual that when using traditional welding methods, the temperature distribution in the pipe joint becomes uneven during the welding operation, resulting in the formation of voids in the joints due to uneven molten solder spreading. In welded pipe joints, fatal defects suchvoids in pipe joints can be used for water supply pipes, because they affect the durability of anti-leakage, it is very difficult to have welded stainless steel pipe joints without thesoldered large cavity formation.
However, a major part of such a magnetic flux composition is made of phosphoric acid, and it contains copper or copper salt as an important component. Due to the narrow activation temperature range and other non-corrosive fluxes and the low thermal conductivity of stainless steel, the pipe joints have many large gaps and are unsatisfactory. It is very difficult to determine the most appropriate time to feed the soft solder to the vector.
However, the resulting paste-like mixture is easily degraded by the process. For the purpose of improving the stability of the solder paste, the solder composition is disclosed in the US Series, for example. Application No. 217832 dated January 14, 1972 has been filed, which contains an amine salt inhibitor to be added to the welding composition. However, the US application does not disclose the solder paste used for welding stainless steel pipes, or the combination ratio is mainly ammonium phosphate and a small part of phosphoric acid.
Another object of the present invention is to add a stainless steel pipe, the chromium oxide film on the surface of the stainless steel is completely removed, and the fear of corrosion of the weld-free stainless steel pipe joint on the activated surface at the brazing temperature provides a method.