Prefabricated valve assembly for installation in a dry-coupling receiving part, which is configured to couple with an associated dry-coupling plug-in part of a fluid-carrying dry coupling; (i) the valve assembly comprises a guide seat ring with a seat ring inner wall and a valve body radially mounted on the seat ring inner wall by means of a guiding radial bearing and slidingly movable axially along the central body axis of the valve assembly, wherein the guide seat ring has a first seat ring end and for coupling can be placed in a locking position secured against rotation about its central body axis; (ii) the valve body comprises a valve head, a valve base and a valve web part mounted by means of the guiding radial bearing on the seat ring inner wall, said valve web part joining the valve head and the valve base together and spacing them apart axially, wherein the valve base situated outside the guide seat ring can be joined to control elements for the application of torque; (iii) the guide seat ring has a valve seat on the first seat ring end, which together with the valve head forms a receiving-part valve, wherein the valve head engages sealingly in the valve seat in the valve closing position and protrudes from the guide seat ring on the first seat ring end in the valve opening position; (iv) the guide seat ring and the valve body are located in a bearing seat of the guiding radial bearing which blocks the relative rotation between the guide seat ring and the valve body and permits relative axial sliding mobility, wherein the guiding radial bearing has corresponding bearing elements (26, 34), namely first bearing elements which protrude on the seat ring inner wall, and second bearing elements which are formed on the valve web part, and wherein the corresponding bearing elements (26, 34) lie in at least one axial bearing seat bearing plane in the bearing seat, characterised in that for assembling and dismantling the valve assembly a key connection is designed and configured between the corresponding bearing elements (26, 34) of the at least one bearing seat bearing plane in such a manner that the bearing seat can be established and conversely released by a relative rotatable displacement and a relative axial displacement between the guide seat ring and the valve body, wherein the corresponding bearing elements (26, 34) can be placed by means of the relative rotatable displacement in free positions outside the bearing seat bearing plane, in which positions the undivided valve body can be guided into the guide seat ring and conversely can be guided out of it, and wherein the corresponding bearing elements (26, 34) can be brought into and out of engagement inside the guide seat ring by means of the relative axial displacement in the bearing seat bearing plane. (i) the valve assembly comprises a guide seat ring with a seat ring inner wall and a valve body radially mounted on the seat ring inner wall by means of a guiding radial bearing and slidingly movable axially along the central body axis of the valve assembly, wherein the guide seat ring has a first seat ring end and for coupling can be placed in a locking position secured against rotation about its central body axis; (ii) the valve body comprises a valve head, a valve base and a valve web part mounted by means of the guiding radial bearing on the seat ring inner wall, said valve web part joining the valve head and the valve base together and spacing them apart axially, wherein the valve base situated outside the guide seat ring can be joined to control elements for the application of torque; (iii) the guide seat ring has a valve seat on the first seat ring end, which together with the valve head forms a receiving-part valve, wherein the valve head engages sealingly in the valve seat in the valve closing position and protrudes from the guide seat ring on the first seat ring end in the valve opening position; (iv) the guide seat ring and the valve body are located in a bearing seat of the guiding radial bearing which blocks the relative rotation between the guide seat ring and the valve body and permits relative axial sliding mobility, wherein the guiding radial bearing has corresponding bearing elements (26, 34), namely first bearing elements which protrude on the seat ring inner wall, and second bearing elements which are formed on the valve web part, and wherein the corresponding bearing elements (26, 34) lie in at least one axial bearing seat bearing plane in the bearing seat,