Residue treatment of sanitary stainless steel pipe fittings after polishing

The surface of sanitary stainless steel pipe fittings should be cleaned formally under dry conditions. 1. In order to clean the surface of sanitary stainless steel pipe fittings, remove discoloration and restore corrosion resistance, there are many post-treatment methods. Here again, we should distinguish between chemical and mechanical methods for sanitary stainless steel pipe fittings. 2. Chemical methods of stainless steel sanitary fittings include: pickling (immersion, pickling paste or spray), auxiliary passivation (after pickling) and electrolytic polishing. Mechanical methods for sanitary stainless steel pipe fittings include: sand blasting, glass or ceramic particle shot blasting, immersion, brushing and polishing. Although all methods can produce weld seams, no mechanical posttreatment will provide corrosion properties suitable for demanding applications. Chemical methods shall be used to remove oxides and other pollutants on the surface of sanitary stainless steel pipe fittings, and mechanical methods may be used to remove the pollution caused by previously removed materials, polishing materials or immersion materials. All kinds of pollution, especially foreign iron particles, may be the source of corrosion, especially in humid environment. Therefore, it is better to clean the surface of sanitary stainless steel pipe fittings by mechanical cleaning under dry conditions.