Closed waterproof thermal recovery gate valve

The invention relates to a closed waterproof thermal recovery gate valve and belongs to the technical field of petroleum pipeline valve manufacture. A bonnet is connected to the upper portion of a valve body through bolts; a support is connected with an external thread on the upper portion of the bonnet through an internal thread on the lower portion in a screwed manner; the upper end of a valve rod is screwed into an internal thread of the lower end of the valve rod nut; a bearing pressing cap is screwed into the internal thread of the upper end of the support, and a lock nut is arranged between the bearing pressing cap and the internal thread; the upper end of the valve rod nut penetrates an inner hole of the bearing pressing cap and extends out of the bearing pressing cap, and the lower end of the valve rod nut is disposed inside the support; two single direction thrust ball bearings are arranged between the lower end face of the bearing pressing cap and a shoulder of the valve rod nut as well as between the shoulder on the valve rod nut and an inner shoulder in the hole of the support; the support is externally covered with a dust cover which is a cylindrical tubular rotary body, an inner hole of the dust cover is in clearance fit with the external diameter of the support, and sealing rings are arranged between fitting surfaces; a gasket is arranged between the lower end face of the lock nut between the bearing pressing cap and the support and the upper end face of the support.