Steel cylindrical vertical tanks are fabricated by industrial method of welded panel rolling. The welded panels are made up of separate, processed on perimeter sheets. The advantage of this method consists in reducing site-welding operations to minimum. This reduction can be obtained because joining and welding of the shells, bottoms, pontoon bottoms and floating roof bottoms are performed at the plant by automatic welding.
The method is as follows: Steels sheets of modular dimensions 1500 mm Е 6000 mm are automatically welded into panels of required dimensions and are rolled on special devices providing their handling and transportation. The roll length amounts to 18 m, the weight is coordinated with the rolling stock load-carrying capacity.
The roll rigidity during transportation and handling is provided by special devices that are included in a delivery set. The main advantages of the method of metal structures fabrication described above, are as follows:
The third stage of the metal construction production takes place at the rolling installation. It consists of assembly-welding platforms-lower and upper decks, canting drum and rolling device. At the upper deck of the assembly-welding platform the sheets are laid out and assembled into the panels, lengthways and cross joints are automatically welded after that. The panel is wound through the canting drum and at the lower deck the second weld is made.
Here radiographic examination of welds is performed.
The panels are rolled on the special frame or shaft stairway. Every panel in the roll is fixed to prevent accidental unrolling.
The roof parts are cut by the guillotine-shears, rod-cutting machine and are stamped by the press. The roof parts are assembled into boards in stocks. The boards are stacked into the packages ready for dispatch and shipping.
The final stage consists in shipping the finished product to the customer, as a rule by rail.