To provide a flat-bottomed cylindrical low-temperature tank structured to be easily shorten construction period, and its construction method.
Instead of the conventional roof construction method of the flat-bottomed cylindrical low-temperature tank, a tank bottom and a cylindrical tank sidewall rising from the tank bottom and having an inner diameter of the same dimension from the lower part to the upper part which has an opening, is manufactured. A tank roof plate is manufactured at the tank bottom, and a fixing ring member having a plurality of through holes along the circumference to fix the peripheral edge of the tank roof plate is manufactured at the upper part of the tank sidewall. A seal structure vertically slidable along the tank side wall is manufactured on the outer periphery of the tank roof plate. Air is blown into a space surrounded by the tank roof plate, tank bottom and tank sidewall, to lift the tank roof plate into the position of the fixing ring member by air pressure, and the tank roof plate and the fixing ring member are welded in the open state of the through holes.
KARASUNO NOBUMI
TOMITA TAKEO
IWANO SATOSHI
