The present invention relates to a screw connector for medical hose systems, which is designed to lock in a half-open sterilizing position. The screw connector comprises a first connection element with a first lumen and an external screw thread and a second connection element with a second lumen and an elastically deformable cap nut with an internal screw thread. The internal screw thread and the external screw thread are configured to be screwed together, wherein the external screw thread has at least a first molding and the internal screw thread has at least a second molding. The internal screw thread and the external screw thread are configured for a mutual screw connection under an elastic deformation of the cap by means of the first molding in at least one predetermined first rotational angle range, without the first molding locking in the second molding. The internal screw thread and the external screw thread, as well as the first molding and the second molding, are configured to lock the first molding into the second molding when the internal screw thread and the external screw thread are screwed together in a predetermined second rotational angle range in which the half-open sterilizing position is adjusted.
