Permalink Reply by JR on August 19, 2010 at 1:01pm
A friend of mine had one of those sets.
It's from the warehouse - it was sold as a "crey boil up pot" for $100. The pot is aluminum and is about 30L - perfect for a 20L batch and 25L if you squeeze it in.
I destroyed the pot by leaving it full of water with nappisan in it and a copper wort chiller for about a week. The pot ended up full of pits. I'm not sure what funny chemistry went on there but the copper chiller was fine.
If you are not scared of aluminium pots then I would probably recommend the set. Or get the burner and attached stand and get another SS pot.
Napisan eats the protective layer on stainless. The "stainless" part of steel is just a layer which REDUCES the ability of the steel to become stained. If you use chemicals on stainless it can break down that protective layer... pretty sure John Palmer convers this in his HTB book.
From my vague memories of having stainless bollards installed on a wharf project, stainless relies on the outer layer of the steel (which has a chromium content) being oxidised from contact with air, to form the stain-resistant chromium oxide layer. If it remains in contact with something that deprives it of the oxygen contact you can get staining problems. If the napisan removes the chromium oxide layer, and it is not then re-exposed to air, then perhaps this is where the problem has begun?
My 28l Aluminium "Cray boiler" from the warehouse (on special for $60 including gas fitting) suffered a similar fate when my wife decided it was a great vessel to use when soaking the oven extractor fan filter in industrial grade chlorine.
She didn't have too many objections at me spending the money on a 50l s/s boil pot after that :)
Stronger chemicals such as bleach and caustic will damage aluminium (strip the protective oxide layer), and stainless to a lesser degree (longer contact time will damage it). That said most breweries and dairy factories use caustic for cleaning, you just have to know how to use it right.
Spot on. Most places use caustic to clean, acid to neutralise & sterilise; then flush with sterile water. Nice if you have it, not so easy for the homebrewer.
Permalink Reply by JR on August 19, 2010 at 3:31pm
Thats why I was surprised I managed to ruin it. Either the warehouse pot isn't aliminum, there was something extra in my napisan (could have been another brand but the active ingredient was sodium perc) or it was something to do with the copper being in there too, or it was purely the amount of time I left it - 1 week.