A German company specializes in x-ray systems for evaluating weld seams in pipes. X-ray systems provide manufacturers with the most comprehensive data, but precise control of the distance between the x-ray source and the surface of the pipe is critical for imaging data quality.


  • Precision
  • Reliability
  • Cost effectiveness
  • Robustness


  • Sensing range up to 40 mm
  • Resolution in µm range
  • Excellent temperature stability
  • Very good repeat accuracy
  • Robust, quasi-embeddable sensor with metal housing
  • Current and voltage outputs
  • Several switch points with a single device

Customer Application

The x-ray system tests weld seams in pipes with diameters from 50mm to 2m. Pipe producers throughout the world build x-ray systems into their production lines to check that pipes used to transport oil or gas by land or sea will remain absolutely impermeable, despite long-term exposure to temperature fluctuations and high pressures. This is only guaranteed if the pipes are free from material faults and weak points, such as tears in the weld seam and trapped air or slag in the metal.

To test for such faults, finished pipes enter an x-ray test room – a radiation-proof bunker controlled from an external PC. The x-ray tube is positioned precisely over the pipe while a flat panel forms the opposite pole of the system. The flat panel is located inside a large pipe or below a small one. Accurate positioning of pipe, flat panel and x-ray source is crucial to achieving optimum test results.

With customers throughout the world, the manufacturer of this x-ray system requires absolutely reliable sensors that perform their critical functions year after year.

Customer Solution

An inductive sensor from the Extra Distance family, Analog Output range (series 509) is ideally suited to the position and distance measurement requirements of this application. Unlike digital sensors, which only supply an absolute value, this sensor captures the entire motion sequence. With no digitization, it has excellent resolution (in µm range) and is particularly suitable for measuring gaps and angles, detecting motion and controlling travel smoothly.

Sensors are positioned to measure both the pipe carriage position (which represents the system’s zero point and is therefore decisive for correct operation) and the distance between the x-ray source and the pipe surface (critical to x-ray result quality).

The analog sensors output a motion sequence as a continuous voltage or current analog signal. This signal changes as the gap between the damping element and the sensing surface changes.

With patented Condist technology, these high performance sensors have a range of 0 to 40 mm (250% higher than the market standard) and deliver the necessary flexibility for testing different pipe diameters.