Dec 11, 2011

Is electropolishing actually necessary given that a 1.0 or greater Cr/Fe ratio can be achieved by passivation alone? The short answer? If a 1.0 Cr/Fe ratio is all you are trying to achieve, no it is not. Now for the long answer. First, the 1.0 or greater Cr/Fe ratio indicated in the ASME BPE standard is a minimal requirement. The best passive and corrosion-resistant surfaces will have a Cr/Fe ratio in excess of 1.5/1, again achievable by passivation alone. The pharmaceutical industry, in most cases, requires a 15-25Ra value typically achieved through a mechanical polishing procedure. It is this procedure that, in my opinion, causes many of the problems experienced today with the formation of the “gray residue” and Class 1 rouge that has plagued end users for years.