Lockable connection device for fluid transfer, and its locking method

The device (1) has a metal locking pin (6') whose spigot end is mounted on a female connector (3). The connector comprises guiding units formed of a groove (11) and radial inner and outer ramps (12, 13) for guiding ends of the pin radially formed on an outer side of a wall. The ends of the pin cooperate with each other to authorize a passage of the pin in a locked position if the spigot end is inserted into the connector in a pre-locking position. The connector comprises an anti-lock stop formed by an upper edge (13a) when the spigot end is not in the pre-locking position relative to the pin. An independent claim is also included for a method for locking a flexible or rigid fluid transfer tube connection device.