It is described a pinning tool (1) for pinning a tubular structure (8) by pressing a pin (4) through a sidewall (80) of the tubular structure (8). The pinning tool (1) comprises: - a tool body (2) configured for receiving the tubular structure (8); - an actuator (5) mounted on the tool body (2), the actuator (5) being provided with a piston rod (52), wherein the actuator (5) is configured for displacing the piston rod (52) in a translational movement; - a pin adaptor (7) releasably coupled to the piston rod (52) of the actuator (5) and being configured for receiving and releasably holding the pin (4) to be pressed through and remain in the sidewall (80) of the tubular structure (8), and - a reaction member (3) for fixing a relative position between the tool body (2) and the tubular structure (8) during pinning, wherein the translational movement of the piston rod (52) causes displacement of the pin adaptor (7), thereby pressing, in operational use, the pin (4) through the sidewall (80) of the tubular structure (8).