Screw connection device for connecting the crimped ends of two tubes

A nut (3) has cylindrical receiving space (7) between front and rear openings (4,5). A receiving space-side surface (11) of nut has threaded portion (10) with internal thread (12). A spacer element (20) between flange (9) and internal thread is held captively and with a predetermined clearance in the receiving space in a preassembled state of nut. The flanges (9,19) of pipe ends (6,18) is pressed against sealing surfaces (24,25) of spacer element, and rear abutment surface (28) of flange (9) is pressed against connecting surface (29) of nut in assembled state.