Abstract: A protective ring for resisting contact corrosion for a connecting element such as a screw which can be fitted to a component and which has a bearing surface for bearing against the component includes a sealing ring of plastic material. The sealing ring is carried on the connecting element in such a position that before the connecting element is tightened the sealing ring provides a bead which projects in the axial direction beyond the bearing surface and which, upon tightening of the connecting element, can be permanently axially braced relative to the component to form an annular sealing surface which extends around the contact surface between the connecting element and the component. The sealing ring has a protective sheathing for the connecting element, which projects in the opposite direction to the bead.