A technique is provided for detecting the surface profile of a seat pocket of a gate valve. An inspection tool is used to detect data at a plurality of points around the bore of the valve. The inspection tool has a sensor that is moveable between a retracted position and an extended position. The inspection tool is disposed within a valve body cavity with the sensor in the retracted position. The sensor of the inspection tool is then extended outward so that it is located within the portion of the bore of the valve having the surface profile to be detected. The sensor is rotated so that the sensor may obtain surface profile data at a plurality of points around the seat pocket of the valve body. The sensor of the inspection tool is connected to a processor-based device, such as a computer. The processor-based device processes the data from the sensor and provides it to a user in a form that is recognizable to the user.