The production of convex bottoms is divided into cold-drawn bottoms (from 900mm to 3000 mm diameter, with thicknesses from 2.5 to 12 mm.) And printed bottoms (from 350 mm to 1270mm diameter, with a minimum thickness of 1 mm and a maximum of 3 mm.) The first ones in the technical sheets are marked with the letters 'A' and 'G', while the printed substrates are autoclave and / or first tank collection, a distinction which must always be mentioned in the procurement orders.
Recently, the production has been integrated with the insertion of the carbon steel funds for pressure devices, 'torospheric' type with or without normalisation heat treatment, depending on the type of steel used.