SEAT STRUCTURE OF BUTTERFLY VALVE

PURPOSE:To facilitate production and the assembly and disassembly on repair by installing a division pipe in demountable ways between the valve trunk of a butterfly valve and a water introducing pipe and installing a seat for preventing the lead of water onto a fixed flange or loose flanges. CONSTITUTION:A division pipe 15 is installed in demountable ways onto a water introducing pipe 5, and a fixed flange 12 having a high rigidity or loose flanges 13a and 13b are installed into the division pipe 15, and a seat 2a is installed onto the flange. Since the division pipe 15 can be made smaller than a valve trunk having the larger dimension and weight, the seat surface 2a installed onto the flanges 12, 13a and 13b can be easily prepared, securing dimension precision, and the gap between a valve body 3 and the seat 2a can be easily reduced to the min., and leak of water can be prevented. Further, since the division pipe 15 and the loose flanges 13a and 13b can be demounted easily, inspection and repairing works are facilitated.