The corrosion of stainless steel is counteracted by passivation. Without passivation, iron or iron oxide exists on the surface of stainless steel. When any machining or fabricating operations are performed, the condition is worsened. Aside from the iron being deposited by tooling, it is also being entrapped underneath the "smeared skin" This is why Summa Processing is so valuable.
Standard passivation by nitric acid immersion attacks iron at the surface. This only partially solves the problem. The remaining iron under the skin will now corrode both inwardly and outwardly. The inward corrosion is known as I.G.A or intergranular attack. The results are metal fatigue and surface corrosion, the latter being disastrous to any food, medical or surgical application. The photographs below indicate how passivation by nitric acid immersion actually raises the microfinish of a surface because it leaves pits where iron had existed. Any high purity application such as gas or liquid valves and pumps, bearings, vacuum systems, or fuel supplies would be subject to detrimental effects without thorough passivation.
Summa Processing resolves this problem entirely. Surface contaminants and the false skin which entraps iron are removed electrochemically. The surface that remains after processing is positively the cleanest, most passive surface possible. The microfinish is lowered and the dimensions with close tolerances do not pose a problem. The rate of metal removal is controllable with this process.