The invention relates to a method and arrangement for determining and indicating the position and depth of an unevenness of the inner surface of a pipe.
Such method is for example disclosed in German patent application No. P 30 03415, corresponding to U.S. patent application Ser. No. 230,050, filed Jan. 29, 1981, now U.S. Pat. No. 4,407,071, which process has the drawback that the mechanical scanning system comes into contact with the pipe wall. In view of the frictional forces that are encountered, errors in the measurements and even jamming of the feelers in imperfections or erosions of the interior surface of the pipe, can result. Due to the mechanical scanning, the period between two measurements is relatively long since the feeler finger must be lifted off the interior pipe wall, shifted in position and then again brought into contact with the pipe wall.