Fitting comprising a fitting body having a fluid passage, a first pipe socket for the connection of a first pipe portion and a second pipe socket for the connection of a second pipe portion with an external thread, and also comprising a coupling unit, which is arranged on the second pipe socket and is intended for releasably connecting the second pipe portion to the second pipe socket, wherein the coupling unit comprises a union nut, which is pivotably mounted on the fitting body and has a cylindrical interior space, which is delimited by an inner surface, wherein the interior space encloses the second pipe socket such that an accommodating space is created between the interior space and pipe socket, it being possible for the second pipe portion which is to be connected to be accommodated in the accommodating space, wherein the inner surface has arranged on it an internal thread, which can be brought into engagement with the external thread of the second pipe portion, and wherein arranged on the outside of the second pipe socket is a sealing element, which interacts with the inner side of the second pipe portion, wherein the coupling unit comprises a securing element, which can provide rotary locking between the second pipe portion and the union nut to counter a release movement of the union nut, characterized in that the coupling unit further comprises a torque-limiting element, which limits the torque applied to the union nut during assembly, in that a drive ring is arranged on the outside of the union nut, wherein the torque-limiting element is arranged between the drive ring and the union nut, and wherein a rotary movement of the drive ring can be transmitted to the union nut via the torque-limiting element, and in that the drive ring has a cavity, in which the union nut is placed, wherein the cavity is designed such that the union nut is located essentially entirely in the cavity. comprising a fitting body having a fluid passage, a first pipe socket for the connection of a first pipe portion and a second pipe socket for the connection of a second pipe portion with an external thread, and also comprising a coupling unit, which is arranged on the second pipe socket and is intended for releasably connecting the second pipe portion to the second pipe socket, wherein the coupling unit comprises a union nut, which is pivotably mounted on the fitting body and has a cylindrical interior space, which is delimited by an inner surface, wherein the interior space encloses the second pipe socket such that an accommodating space is created between the interior space and pipe socket, it being possible for the second pipe portion which is to be connected to be accommodated in the accommodating space, wherein the inner surface has arranged on it an internal thread, which can be brought into engagement with the external thread of the second pipe portion, and wherein arranged on the outside of the second pipe socket is a sealing element, which interacts with the inner side of the second pipe portion, wherein the coupling unit comprises a securing element, which can provide rotary locking between the second pipe portion and the union nut to counter a release movement of the union nut, characterized in that the coupling unit further comprises a torque-limiting element, which limits the torque applied to the union nut during assembly, in that a drive ring is arranged on the outside of the union nut, wherein the torque-limiting element is arranged between the drive ring and the union nut, and wherein a rotary movement of the drive ring can be transmitted to the union nut via the torque-limiting element, and in that the drive ring has a cavity, in which the union nut is placed, wherein the cavity is designed such that the union nut is located essentially entirely in the cavity.