A pinning tool is for pinning a tubular structure by pressing a pin through a sidewall of the tubular structure. The pinning tool comprises: a tool body configured for receiving the tubular structure; an actuator mounted on the tool body, the actuator being provided with a piston rod, wherein the actuator is configured for displacing the piston rod in a translational movement; a pin adaptor releasably coupled to the piston rod of the actuator and being configured for receiving and releasably holding the pin to be pressed through and remain in the sidewall of the tubular structure, and a reaction member for fixing a relative position between the tool body and the tubular structure during pinning, wherein the translational movement of the piston rod causes displacement of the pin adaptor, thereby pressing, in operational use, the pin through the sidewall of the tubular structure.