Stainless steel filter cartridges in the production when it comes to welding, since it is welded, there must be a change in temperature, the high temperature will cause discoloration of stainless steel cartridge surface, affect the appearance, in particular, butt welding the filter cartridge, in white stainless steel surface burning a black mark, did not look too beautiful, we generally will use the factory to handle it polished, stainless steel filter cartridge becomes white bright colors, because so much a part of the program costs will increase, so If the client taking into account the filter cartridge is used internally, there is no requirement for the surface, then there is no need to do this step treatment, the cost may be lowered appropriate part.