Grinding, Welding, Testing, Vacuuming: Qualification of repair tasks inside of pipe systems in nuclear engineering

The repair of pipelines that are not accessible from outside poses big problems for various operators. In practice the contractor can't get from outside to the pipeline to be detected and worked on in special areas at all or only to a limited extent with the greatest exertions, costs, and shut-down times.

In order to obviate this problem situation, INSPECTOR SYSTEMS received the order for qualifying a repair methodology to repair flaws inside of pipe systems. In this connection test pipes in the DN 200 mm range were visually inspected from inside with the aid of ultrasonic testing technology. After that a grinding robot ground the detected flaws from inside. The grinding tasks were executed so that these could ultimately be welded back together with an internal welding robot.

Grinding of the weld area follows again as an additional work step to align the pipe's inner wall with the surroundings and produce a testable surface. The final ultrasonic testing came into use after that. It was intended guarantee that no additional flaws or incomplete fusions originated from the welding. The pipe was freed of swarf with the aid of a vacuuming robot after each of the grinding tasks.

The entire repair process was conducted in the Paks Hungarian nuclear power station and was qualified by the competent authority and a Hungarian inspector.

The challenge of the overall repair service consisted of bringing together various kinds of machining and test technologies and adapting them to a single pipe robot in an inner diameter of barely 200 mm. Seven distinct work steps in all were needed for one flaw (testing — grinding — vacuuming — welding — grinding — vacuuming — testing). INSPECTOR SYSTEMS executed the entire contract as full service.

Only INSPECTOR SYSTEMS's profound expertise, acquired during the past decades, is able to cover these varied tasks from a single source, where our partner ARC Machines provides the internal welding technology.

The client ultimately qualified the complete repair process, and it's now available for potential uses.