Fluid connection device intended to be adapted on a double envelope fluid line to enable connection and disconnection between a first circuit (2a, 3) for circulation of at least one fluid (G1, G2) and a second circuit for circulation of at least one fluid of the same fluid line, the first circulation circuit (2a, 3) comprising a first internal circuit of a process fluid and a first external circuit forming an envelope extending around the first internal circuit, a surveillance fluid at least one parameter of which is tested to detect a leak or rupture of the fluid line, and the second circulation circuit comprising at least one second internal circuit of the process fluid and a second external circuit of the monitoring fluid, the fluid connection device comprising a first fluid connector (9, 10) formed by a fluid connection of the second internal circuit and a fluid connection of the first internal circuit to enable connection and disconnection between the first internal circuit and the second internal circuit of the process fluid, the device also comprising a second fluid connector (12, 4, 5, 6, 7, 8, 11) to enable connection and disconnection between the first external circuit and the second external circuit of the fluid line, comprising: - a fluid connection from the second external circuit in which the fluid connection of the second internal circuit is at least partially housed, said fluid connection of the second external circuit comprising at least one first bayonet type attachment means, particularly comprising at least one bayonet attachment pin, on its external surface, - a fluid connection (4, 5, 6, 7, 8, 11) of the first external circuit comprising an envelope connection part, mounted free to translate and rotate relative to a guide part fixed to the first internal circuit, the envelope connection part at least partially housing the first fluid connector (9, 10) and defining an internal volume for circulation of the monitoring fluid at the first fluid connector (9, 10), the envelope connection part also comprising at least one second attachment means of the bayonet type, particularly at least one bayonet attachment notch fitted with a stop, on its external surface designed to cooperate with the first bayonet type attachment means of the fluid connection of the second external circuit, particularly by sliding of said at least one bayonet attachment pin in said at least one bayonet attachment notch and locking at the stop, to enable connection and disconnection by a bayonet type attachment between the first external circuit and the second external circuit of the fluid line, characterised in that the fluid connection (4, 5, 6, 7, 8, 11) of the first external circuit also comprises an interface part that will be fixed to the first external circuit of the first circulation circuit (2a, 3), the interface part comprising an internal space to enable insertion of the guide part, the guide part being designed to at least partly extend inside the first external circuit and itself comprising an internal space for passage of the first internal circuit of the first circulation circuit (2a, 3). - a fluid connection from the second external circuit in which the fluid connection of the second internal circuit is at least partially housed, said fluid connection of the second external circuit comprising at least one first bayonet type attachment means, particularly comprising at least one bayonet attachment pin, on its external surface, - a fluid connection (4, 5, 6, 7, 8, 11) of the first external circuit comprising an envelope connection part, mounted free to translate and rotate relative to a guide part fixed to the first internal circuit, the envelope connection part at least partially housing the first fluid connector (9, 10) and defining an internal volume for circulation of the monitoring fluid at the first fluid connector (9, 10), the envelope connection part also comprising at least one second attachment means of the bayonet type, particularly at least one bayonet attachment notch fitted with a stop, on its external surface designed to cooperate with the first bayonet type attachment means of the fluid connection of the second external circuit, particularly by sliding of said at least one bayonet attachment pin in said at least one bayonet attachment notch and locking at the stop, to enable connection and disconnection by a bayonet type attachment between the first external circuit and the second external circuit of the fluid line,