Abstract: A stopper for an inspection hole to give an X-ray inspection probe access to the inside of a pipe or other apparatus wherein the stopper comprises a cylindrical outer component (6) having an open end and an inside screw thread (10), said outer component being welded to the wall (1) of said pipe or other apparatus and leaving an outside end protruding therefrom, and a cylindrical inner component (11) having a blind hole and an outside screw thread, said inner component being screwed into the inside screw thread of the outer component and having an outside end which is welded (12) around its periphery to the projecting outside end of the outer component, said blind hole being equipped with means (13) which allow the inner component to be unscrewed from the outer component after the weld (12) joining the outside ends of said components has been broken.