The invention belongs to the technical field of in-service inspection of pressure pipes, and discloses an anti-torsion long-
stroke multistage sealing telescopic structure which comprises a main cable driving guide
assembly and a rigid chain driving
assembly which are connected, the rigid chain driving
assembly is installed at one end of a support guide rail assembly, and a rigid chain
library is arranged below the support guide rail assembly. A rigid chain is arranged in the rigid chain
library, the multi-stage telescopic sleeve is arranged on the support guide rail assembly in a penetrating mode, the front end of the rigid chain is connected with the
tail end of the multi-stage telescopic sleeve, and the rigid chain driving assembly drives the rigid chain to move so as to drive the multi-stage telescopic sleeve to retract and expand. The in-service inspection of the CANDU
nuclear reactor pressure pipe can be realized, the driving
stroke is long, the circumferential
torsional rigidity is enough, the sealing performance is realized, the inspection tool is continuously pushed forwards, the
stroke range of the inspection tool covers the whole length of the
pressure pipe, and in the inspection execution process, each sealing part of each stage of telescopic component does not generate visible leakage.