Bolt pre-tightening pneumatic device

The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a bolt pre-tightening pneumatic device. According to the embodiment of the invention, the controldevice can control each rotary cylinder to continuously work under the first control mode until the angle data of the rotary cylinder acquired by the control device meets the first preset condition,so that the control device can accurately control each rotary cylinder to screw a corresponding bolt at a proper angle, and the bolt screwing efficiency is improved. Therefore, the lifting bolt plateof the thermocouple is uniformly lifted to a proper height relative to the lifting bolt supporting plate of the thermocouple, so that the mounting quality and the working efficiency of the mechanicalseal of the thermocouple are improved, and the radiation dose borne by a maintainer is effectively reduced; in addition, the bolt pre-tightening pneumatic device disclosed by the embodiment of the invention is compact in structu