Inner supporting device for installing large pressure steel pipe

The invention discloses an inner supporting device for installing a large pressure steel pipe, and belongs to the technical field of pressure steel pipe construction. The inner supporting device comprises a hydraulic system and an inner supporting device body, the inner supporting device body comprises a shell, a plurality of supporting arms are arranged on the outer wall of the shell in a circumferential distribution mode, one end of each supporting arm penetrates through the outer wall of the shell, a driving mechanism is arranged in the shell, the end, located in the shell, of the supporting arm is connected with the driving mechanism, and the driving mechanism is used for adjusting the length of the part, extending out of the shell, of the supporting arm. According to the scheme, in the using process, two threaded sleeves can be driven to move reversely at the same time by rotating a first two-way screw rod, the length of the part, extending out of the shell, of the supporting arm is adjusted, when the in