Weld joint cutting system for valve seat ring of highly put valve and cutting device thereof

The invention relates to a weld joint cutting system for a valve seat ring of a highly put valve and a cutting device thereof. The highly put valve comprises a valve body, a valve seat ring and a weldjoint, wherein the valve body comprises at least two transverse pipes and a vertical pipe located between the transverse pipes and communicating to the transverse pipes, each of the transverse pipescomprises two branch pipes which are separately located on two sides of the vertical pipe, the valve seat ring is located in each branch pipe, and one end of the valve seat ring is hermetically connected to the branch pipe through the weld joint; the valve seat ring weld joint cutting device comprises a mounting rack, a rotating mechanism and a milling cutter mechanism, wherein the mounting rack is arranged through the vertical pipe; the rotating mechanism comprises a rotating shaft which extends transversely, is rotatably connected to the end, close to the valve seat ring, of the mounting rack, and can rotate freely a