The WeldROVER is an easy-to-operate motorised scanner for ultrasonic weld inspection on ferromagnetic material. Its wheels are strongly magnetic to hold on to the pipe or pressure vessel being tested. Smaller, lighter and simpler than the PipeWizard, it is designed for applications where zone discrimination is not required. It provides one-axis encoding and full data storage.

For circumferential welds, the WeldROVER can be used on pipes from 4 inches in diameter to flat parts. For longitudinal (long-seam) welds, it can be used on pipes of 30 inches diameter or more. This wide range is accommodated by adjustable rotating probe holder arms. Reconfiguring for a new setup can be completed in as little as two minutes.

Depending on pipe diameter, different combinations of probes can be used. Typically one pair of phased array (PA) ultrasound (UT) probes are used with one or two pairs of time of flight diffraction (TOFD) probes.

Motion is controlled with a simple hand-held remote with forwards and backwards buttons and a speed control switch. There is also an emergency stop button on top of the scanner itself. A laser guide assists the operator in keeping the probes aligned with the centre of the weld. The WeldROVER is steered manually using a bar that can be mounted at the back or front of the scanner.

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WeldROVER performance

The first WeldROVERs in Australia were delivered to Bureau Veritas in Melbourne early in 2009 and were immediately shipped to Sydney to test 56 inch and 72 inch diameter pipes on the Water Delivery Alliance Desalination project. The systems were then used to test slurry line pipes with diameters of 30, 32 and 48 inches. Since their purchase, the WeldROVERs have been in continuous use with both PA and TOFD. Bureau Veritas has now tested over 400 km of welds with the WeldROVERs without problems.

The WeldROVER is one of Olympus’ PV-200 range of products which combine PA, conventional UT and TOFD for weld inspection. The product has been used extensively overseas for both pipeline and pressure vessel testing.

Probability of detection can be increased by using independent non-destructive testing methods, but in practice, time and expense usually preclude combining methods such as UT and radiography. While PA and TOFD are both ultrasonic methods, they are different in that PA uses reflected signals while TOFD uses diffraction. Detection with TOFD is therefore not dependant on the flaw orientation. For thicker welds, TOFD can provide greater coverage with one scan, secondary verification of data and improved sizing ability for very little extra cost in either components or time.

When used by a qualified operator according to a qualified procedure, the WeldROVER can meet all the requirements of ASME, AWS, API and similar codes. Full code compliance requires calibration of every focal law. The Olympus software has a ‘wizard’ which guides users through calibrating velocity, sensitivity (ACG as defined by ASME), time of flight and time-corrected gain.