Thank you SJones and EdStainless for your input. SJones thank you for your links, I had been trying to get that Tuthill and Avery reference. Got hold of ASTM380 on Saturday. I think i have all the literature, though lack practical experience to inspect the vessels.
EdStainless - these are completely new items, straight from the manufacturer. Sadly to say, the importer was not very helpful on this issue (I just met him on the weekend) - he was unable to state the current finish on vessels, and described passivating as boiling with water for 20minutes. I was hoping that he could at least clarify if welds had been pickled.
You ask "Why do you think that you need to passivate?".
My understanding is that you passivate so that the vessels to avoid problems such as these described in a home brew article (and to protect your investment):
The main problem was that surface residues would not wash or scrub away. These residues began to affect heat transfer in the kettle and introduced undesirable flavors in the fermentors. I spoke with a local microbrewery about this, only to find that they were encountering similar problems themselves.
Do you see value in the two NaOH steps (pre and post passivation) when using the citrate protocol?
Is there any way to visually determine whether welds have been pickled, or electropolished (what do these types of finish it look like?) And heat tint - is that pretty easy to identify? Any other imperfections I need to learn how to identify before determining if we are ready to clean and passivate (without pickling, for example)? I will research further on these specifics, but any information anyone has have regarding what to look for when inspecting a structure of unspecified finish would be appreciated. I had a quick look, and as far as I could tell, the inner surfaces looked smooth (sorry for the unsophisticated descriptions) and the outside had a high polished sheen. I noted that inner surface of one of the vessels had a 2 inch scratch. Should this be polished out (how?).
Thanks in advance,