Cloa, thank you for your reply. I forgot to mention that we already use this technology (pots with solder on 480deg C). We would only like to switch from PbSn5Ag2 to Sn99Cu solder. It means that if the pot material was subject to cracking due to exposure to molten it would already rupture...
We would like to switch from lead to non-lead (Rohs compliant) solder. Soldering operation is carried out in a baths made of acid resistant stainless steel. Cca 2 kg of solder is melted in a pot at cca 480 deg C. Composition of new solder we would like to use is Sn99Cu1. I've heard some rumors...