Feb 2 2012
Exova has concluded work on a major Immersion Ultrasonic Testing (IUT) project for oil major, Chevron.
The project, which took place at the Exova laboratories in Spijkenisse, Netherlands, enabled Chevron pipeline welds to be inspected, with test rings being submitted for examination.
The IUT technique has recently been introduced by Exova as part of the Automated Ultrasonic Testing (AUT) validation procedure for girth weld inspection.
The testing service is particularly relevant for discovering smaller defects as a result of the high accuracy robotics and enhanced immersive testing environment, which helps the industry to improve the determination of the Probability Of Detection (POD) as part of any AUT validation.
An increased number of indications can be identified because of the service, such as cracking, porosity, incomplete penetration, inclusions, lack of sidewall fusion, and related defects that can compromise the pipelines girth weld strength.
Sander van Nieuwenhuijzen, General manager of Exova in The Netherlands and Norway, said: "Immersion Ultrasonic Testing plays a major part in the Automated Ultrasonic Testing qualification process. This project is just the first stage of a development programme that the team is working hard on to develop a centre of excellence for future procedures and AUT validation expertise.
"It's vital that any defect in the welds are detected, accurately located, sized and reported quickly and that's why Chevron worked with Exova, ensuring enhanced inspection detection and sizing capabilities. It brings them a confidence that the pipeline welds are free from critical defects."
Exova has worked with Chevron for a number of years, providing high quality flaw sectioning and reporting services. The first step for the project was for the two firms to work together to develop, qualify and establish available IUT facilities in close proximity to where pipeline qualification work was taking place.
This led to the first Exova laboratory being chosen in the Netherlands before progressing on to Exova's laboratory in Houston, USA.
Additional effort was allocated to experimenting with ring thickness to demonstrate that this does not have the impact in sensitivity. A calibration process was also designed that constructs signal characteristics and thresholds closely mirroring those used in the AUT system to ensure as near possible like-for-like examination conditions.
Sander concluded: "This IUT technique offers many benefits. It can be applied for any kind of girth weld diameter and wall thickness, as well as any material, from carbon steel to corrosion resistant alloy. It also means that pipeline contractors can take advantage of Exova's global network of laboratories that offer the IUT section of the AUT qualification process."