The innovative method of constructing large-sized roofs (41 m in diameter) of oil reservoirs. The sizes of the individual sections of the umbrella-type roof structure were reduced by dividing them into two parts. As a result it was possible to increase the scope of shop production and facilitate transport and assembly, thus reducing total costs. Figures present joints made using shielded metal arc welding and self-shielded tubular-cored arc welding.