Method and device for measuring in situ the gap between two given elements in a tubular pipe

Method for measuring a gap separating a vault of at least one end fitting and a given element of one end of a terminal part of a pipe, the method comprising the steps of:

• moving at least two measuring devices along the inside of the pipe, each said device comprising a respective high resolution eddy-current sensor, said at least two sensors being mounted on a common support, said support being movable inside and along the pipe, the sensors being spaced from one another on said support by a fixed distance E;
• carrying out at least one series of measurements during the movement of the measuring devices in the end fitting, the measurements comprising the steps of:
• detecting in real time with each of said sensors the passage of a pair of consecutive spatial transitions defined respectively by the vault of the end fitting and the end of the terminal part of the pipe;
• triggering the measurements for a predetermined time between the detections of said transitions;
• storing the measurements in the form of signals in at least one memory;
• and
• processing the stored signals in order to determine a time offset ΔT between detection of a given transition by the two sensors and a time T1 or T2 taken by one of said sensors to run a gap D between the two consecutive transitions, and to determine from the values thus obtained and from said fixed distance E, the value of said gap separating said two consecutive transitions.