High-precision geared ring used for subsea inspection system

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HepcoMotion has supplied a standard ring slide and stainless steel slide to Sonomatic for use in an innovative inspection system for measuring the ovality of subsea pipelines.

Hot-tap technology is an established method of connecting sections of sub-sea pipelines without stopping production. Once limited to relatively shallow installations, the technology is now achievable to depths of 150m. Developing innovative inspection techniques to complement such engineering achievements is the commercial role of Sonomatic. For example, it recently developed a system for checking the integrity of welds for a deep hot-tap project in the North Sea, which it describes as a breakthrough in the field of pipeline NDT (non-destructive testing).

With its roots in nuclear engineering, Sonomatic is a worldwide organisation with more than 25 years' expertise in ultrasonic inspection design, development and application. Today it is focussed mainly on the sub-sea oil and gas industry, as well as nuclear and power generation, but also extends into work for general refineries and the chemical processing industries.

Many of the pipeline projects in which Sonomatic is involved are of significant economic importance and carry environmental implications. As a result the design and production of its bespoke NDT systems are often to a tight time scale and outsourced components and systems need to be 'right first time.' Elements for a recent sub-sea hot-tap project were no exception.

Ovality inspection

Sonomatic was contracted to perform an ultrasonic ovality inspection of a key area on a high-profile pipeline that would be used for a sub-sea hot-tap. A ring slide was required as the main medium to manoeuvre ultrasonic probes around the pipe and a HepcoMotion product was selected. Sonomatic's Chris Krugel explains: "We needed a high-precision geared ring to fit existing automated sub-sea equipment and to accommodate new features that were specific to this project. The quality and ready availability of the HepcoMotion ring made it a clear choice."

The order comprised a standard ring slide and stainless steel slide, supplied as an assembled bearing. It is driven in situ by the scanner for 1500mm to produce radial scans every 250mm on the full 360-degree section, with a positioning accuracy of 0.5mm. Krugel adds: "It fitted in exactly as planned from the early concept stages of the project. The main drive unit needed no modification and this allowed us to move swiftly on to more important issues."

Consequently the ultrasonic ovality inspection system was completed in time and on budget, earning Sonomatic another important credit: it became the first UK company to accomplish this technique.

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