The essential difference is corrosion resistance. After 6-8 h acid soak, rinse and N2/CDA blow-off, boats dry in the graphite-boat oven - resistance must be strong or acid seeps in and causes irreversible loss. Interiors use corrosion-resistant stainless with mature welding and polished seams. Ordinary ovens mainly need uniform temperature, good structure, smart operation and easy service, with lower corrosion demand, so they cost much less to build.
