It is not clear what is meant here by 'pure steam'. Are we talking about steam for any pharmaceutical or food industry use or something else ? Is it superheated or saturated steam and at what pressure/temp. ? The steam purity will depend on the feedwater treatment part. Ordinarily, superheated steam is quite non-corrosive for most of the application & hence your apprehension seems a bit unfounded. In case you need a more detailed answer, please specify the parameters (pr./temp//feedwater treatment details like deaeration, dosing of oxygen scavenger, phosphate treatment if any and final use of steam etc.) With regards