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Australia Pipeline First to Use Computed Radiography Inspection Technology

Posted on April 30, 2009

A girth weld pipeline in Australia is the first pipeline to be completely inspected using computed radiography. Global Technical Services Group (GTSG) performed the inspection, using GE Sensing & Inspection Technologies’ CR50P portable scanner. The team inspected girth welds on the clad pipe, which consisted of 128 km of 18 inch pipe, during laybarge operation on the northwest shelf in western Australia.

The 18-inch diameter pipeline, which handles sour gas, is clad in stainless steel, has a wall thickness of around 1-inch and a surface temperature of 220°C. A particularly important requirement of the girth weld inspection was a very fast cycle time.

Computed Radiography was chosen for its fast exposure and scanning times to easily meet the cycle constraints. The only problem was that the technique did not carry DNV approval for this kind of work. Consequently, GTSG arranged for inspectors from DNV, a global risk management and certification agency, to fly out to the site, to carry out the required approval procedures. As a result, the technique was approved to DNV OS-F101 and it has proved possible to achieve better than 1.2% sensitivity at 100µm resolution, a quality equal to that achievable by film radiography.

GE’s CR50P weighs just 22 kg (48.5 lb) and offers excellent image quality through its optimized optics and a scan resolution which can be user variable from 50 to 130µm pixel pitch. Plates can be fed on a continuous basis, with one plate being fed into the unit while another plate is being scanned. Results are displayed on a black and white monitor with a resolution of 3 million pixels and 65000 grey scale.

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