Patent ID: 8393649

Claim:
A flange connection structure including a flange formed in a pipe for flowing a fluid therethrough, and a flange formed in another pipe for flowing the fluid therethrough, the flanges being fastened by bolts, whereby flange surfaces of the flanges are joined together to couple the pipes together, or a flange connection structure including a flange formed in a manhole of a tank for storing a fluid and a flange formed in a cover, the flanges being fastened by bolts, whereby flange surfaces of the flanges are joined together to close the manhole with the cover, or a flange connection structure including a flange formed in a pipe and a flange formed in a cover, the flanges being fastened by bolts, whereby flange surfaces of the flanges are joined together to close the pipe with the cover, the flange connection structure, comprising: an annular seal groove formed in the flange surface of one of the flanges; a pouring passage formed in the one of the flanges for bringing the seal groove and an outer surface of the one of the flanges into communication with each other; a discharge passage formed in the one of the flanges for bringing the seal groove and the outer surface of the one of the flanges into communication with each other; sealing liquid pouring means connected to the pouring passage for pouring a sealing liquid into the seal groove; and a discharge device connected to the discharge passage for discharging a gas contained in the sealing liquid to an outside, while preventing the sealing liquid, which has exited from the discharge passage, from being released to the outside.