Gate valves are widely used in hydropower stations. These valves are subjected to abusive working conditions. Flange connection is the common connection mode in hydropower station gate valves. Flange connection is considered the most suitable connection method for gate valves of hydropower station for many reasons. This connection can withstand the tensile, compressive, torsional and shear strength. Flange connection is a removable joint with convenient disassembly, high connection strength and good tightness.

According to the shape of the joint surface, the flange connection can be divided into smooth type and concavo-convex type. Smooth type is suitable for gate valves with low operating pressure. In addition to the flange connection, gate valve connection also has a thread connection or sleeve connection, which is a relatively simple connection method, and can reliably prevent leakage.