Marine ultralow-temperature stop valve with lock

A marine ultra-low temperature stop valve with a lock is used for locking and opening a pipeline passage at ultra-low temperature and comprises a valve rod, a valve seat and a valve seat, the valve body is provided with a cavity, liquid can flow in the cavity, and the lower end of the valve rod is inserted into the cavity of the valve body; one end of the valve disc is connected with the lower end part of the valve rod, and the valve disc is positioned in the cavity of the valve body; the valve cover is arranged at the top of the valve body, and the lower end of the valve cover is fixedly connected with the upper end of the valve body through a fastener; the hand wheel is in threaded connection with the upper end part of the valve rod through a square tenon, and the rotatable hand wheel enables the valve rod to rotate and move up and down through rotation of the square tenon, so that opening and closing of the stop valve are realized; and the stop valve locking assembly can limit the up-and-down movement ampl