NON-DESTRUCTIVE testing specialist Applus RTD UK has chosen Offshore Europe as the platform to launch what is one of the most significant and, for the North Sea, most relevant integrity technologies set to appear at the show.
Designed to ensure operational suitability and prolong the life of vital assets, the company is offering what it says is the first fully customisable NDT phased-array system by combining and integrating ultrasonic phased array and time of flight diffraction (TOFD) techniques with alternating current field measurement (ACFM).
Applus RTD tested the system in 130m (426ft) of water offshore Australia and the entire project was completed using a remotely-operated vehicle working with custom-designed tools .
The test centred on detailed site preparation, coating removal, inspection and coating reinstatement. This was carried out at a number of locations where inspection for intergranular stress corrosion cracking (IGSCC) of 12in 13 Chrome (13Cr) butt-welded joints was required.
“First and foremost, our focus was on ensuring that the test was safe and incident-free – particularly as it called for the use of new equipment and procedures, people and a considerable volume of surface deployment systems and deck operations,” advanced NDT manager Charlie Lawther told Energy.
“The test was passed with flying colours – the fact we recorded no incidents or accidents is testament to our commitment to quality, health, safety and the environment throughout all of Applus RTD’s research and development operations.
“Close collaboration was at the core of the test, and the commitment shown by all involved could clearly be seen by the fact that the inspection was completed in half the time planned – resulting in a significant cost saving to the client.”
An international trials team, including specialists from the company’s Aberdeen base, handled all tool works, including design and manufacture, as well as trial operations and final inspection of the butt-welded joints under scrutiny.
Prior to the inspection itself, Applus RTD carried out trials to determine the best way to detect IGSCC in 13Cr material. The highest detection probability for the critical internal weld root area was found to be with a combination of phased-array and TOFD technologies.
Applus RTD says the tool has been designed for deployment by virtually any make of workclass ROV, with the concept using the vessel to position the tool as closely as possible to the weld under inspection.
“Once in position, the ROV moves away and all further positioning and movement of the probe is carried out remotely from the support vessel – making the technique hugely flexible and applicable in virtually any situation if conditions permit,” said Lawther.
“The tooling worked perfectly first time, and the employment of ROV-deployed tooling enabled twice as many welds to be inspected for the same cost compared with a diver-led inspection campaign.
“As far as performance was concerned, the test delivered across every key area – schedule, cost and inspection integrity. Persons on board constraints did limit the ability to carry out resource capacity offshore; the fact that all involved were able to maintain equipment up-time was a considerable achievement.”
Applus RTD has more than 350 UK staff based in Aberdeen, Falkirk, Great Yarmouth, Teesside and Warrington.