An externally threaded clamping and sealing bolt (10) is peripherally coated at the far end of the thread (11) by coating material (12). The holding part (13) has a first assembly hole (13a) and a seal (14) between part (13) and an internally threaded housing (15) has a second assembly hole (14a). Thus the bolt (10) is screwed into the housing via the respective assembly holes (13a,14a) in holder and seal to anchor the seal firmly between the part and the housing. The inside diameter of a recessed sector (20) in the centre part of the housing thread (16a) exceeds the outside diameter of the bolt thread (11) and the depth of this recessed sector (20) is such that the end of the bolt thread on the coated (12) side of the bolt head lies below the seal (14) and thus fully within the recess (20) and in this way engaged with the inside thread (16a) of the housing.
