The invention discloses an eccentric semi-
ball valve capable of being maintained on line. The eccentric semi-
ball valve comprises a valve body, a valve element, a sealing seat and a driving
assembly. A valve cavity is formed in the valve body, a first opening, a second opening and a maintenance opening which are communicated with the valve cavity are further formed in the valve body, and a detachable valve
deck is connected outside the maintenance opening in a sealed mode. The valve element is rotatably installed in the valve cavity and comprises a sealing disc and a main sealing piece arranged on the sealing disc, and the main sealing piece can rotate along with the valve element and switch the position between the first opening and the maintenance opening. The sealing seat is positioned in the maintenance opening; the driving
assembly is connected with the sealing seat and can drive the sealing seat to rotate; during online maintenance, the driving
assembly drives the sealing seat to rotate to be in contact sealing with the sealing disc, the sealing disc, the sealing seat and the valve
deck form an isolation cavity at the maintenance opening, the main sealing piece is located in the isolation cavity, and the main sealing piece can be maintained by disassembling the valve
deck. According to the scheme, the eccentric semi-
ball valve is simpler in structure, and the overhauling process is faster.