Precision measurement with Contrinex long-range analogue inductives

The integrity of weld seams in pipes used to transport oil or gas across land or sea is ensured using x-ray testing. The x-ray test systems used for this require precision control of the distance between the x-ray source and the surface of the pipe because this is critical for the quality of the imaging data.

Customer Application

A producer of pipes ranging in diameter from 50mm to 2m has x-ray testing systems integrated to the end of their production lines to ensure the pipes they manufacture will not leak and are impermeable. Pipes for pipelines for example must resist long-term exposure to harsh environments and withstand high pressures and fluctuations in temperature. Therefore, they must be guaranteed to be free from material faults and weak points, such as flaws in the weld seam, like trapped air or slag in the metal.

The final inspection of the pipe involves the pipes entering an x-ray test room, which is a radiation-proof bunker. The x-ray source 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, the flat panel and the x-ray source is crucial to achieving optimum test results and therefore accurate and reliable sensors are critical to production efficiency.

Customer Solution

Contrinex analogue inductive sensors from their Extra Distance 509 Series family, available from PLUS Automation, are perfect for the position and distance measurement requirements of this application. The sensors provide an analogue value for the entire motion sequence of the x-ray inspection. Their excellent resolution in µm range is particularly suitable for measuring gaps and angles, detecting motion and controlling travel smoothly.

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

The analogue sensors output a continuous voltage or current analogue signal which reflects the gap between the damping element and the sensing surface.

With Contrinex’s patent-protected Condist technology, these high-performance analogue sensors provide a sensing range that is more than twice the distance offered by competitors. The M30 versions used in this application offer a sensing range of 0 to 40 mm and so they can provide the flexibility required for testing the numerous pipe diameters being manufactured. The solution excels because it is durable, adaptable, reliable and was also fast and simple to install.

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