Corrosion Resistant Alloy (CRA) clad pipe is becoming increasingly important in preventing corrosion. The welding process is critical to the successful fabrication of CRA clad pipes and consequently the ability for the pipeline owner to extend the life of their pipeline. However, the welding process itself is very challenging.

To measure the critical features of CRA welds such as HiLo (joint misalignment), weld height, width, and lack of penetration or fusion, OMS has introduced WeldChecker, a system that comprises a high-resolution digital video camera for video inspection, and a laser scanner to gather pipe geometry across both pipe inner walls near to the weld, and across the entire weld. This is critical during the Pre-Qualification Tests (PQT) in order to qualify the welding process, equipment and staff for the project. This not only allows the client to develop its process and to fully understand the welding parameters, but enables them to demonstrate to their customer a high level of weld information and to show full compliance with stringent pipeline specifications.

The ability to give closure on tough decisions regularly encountered by the welding inspector could prove invaluable in saving time, while also ensuring only the highest quality welds are accepted, leading to longer lifespan. When to use WeldChecker is an important factor – timing is critical in order to maximise the benefits. Video-only inspection tends to raise as many questions as it answers, often meaning that pipe joints need to be cut out to mitigate any risks, even if they turn out to be acceptable upon closer inspection later.

Ultrasonic testing, although very detailed, can only be performed after the weld has been completed. There will have been multiple weld passes before finishing the cap of the weld. This means that if a flaw is found, many hours of work may have been wasted. The OMS WeldChecker can be used to inspect after the second pass, so if there is a flaw in the root weld, it can be cut out at this point – saving time and money.

Another technical challenge is the ability to inspect welds around curved pipes. Many of OMS’ clients use CRA materials on subsea structures, such as PLETs (Pipeline End Terminators) and PLEMs (Pipeline End Manifolds). These tend to have very tight bends, as little as 1D (1 x diameter) on occasion. OMS has designed and produced a new version of the WeldChecker, which has the same design concept as a London ‘bendy-bus’ with a modular, flexible design. The advance in hardware has driven the capability forward, allowing previously inaccessible welds to be measured for compliance – guaranteeing they meet the client’s specification.

Taking this technology to the next level, OMS has developed more compact tools that are able to fit inside ever-smaller pipe diameters. The capability is now at just 4in internal diameter. OMS can inspect welds using both laser measurement and visual data at approximately 100mm diameter, and around bends in pipes.

OMS is looking at the application of this technology to a number of different situations. One application is to mount the tool to the line up clamps for use in the critical welding path both onshore and offshore during pipeline welding. Another application is the inspection of tie-in welds on welded spooled stalks of pipe – this means while these pipes are spooled onto the vessel, the WeldChecker would be driven by crawler perhaps 1km to perform the weld scan.  Finally, it could be used on older pipes and structures to measure the extent of corrosion or pitting, or perhaps to measure the extent of features in the pipe wall.

The device has also seen interest from the aerospace and nuclear sectors. Large operators are now asking for tighter tolerances to maximise production life, and also to make the pipelines safer through better welds. OMS offers a solution for both operators and welders – seen, measured, quantified, and approved.