TPi November 2014

Pipeline welds: seen, measured, quantified and approved by Hugh Davies of Optical Metrology Services (OMS) Ltd, UK

The OMS WeldChecker system 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 also enables it to demonstrate to its customer an unrivalled 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 also an important factor – timing is critical in order to maximise the benefits of the system. 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, and this means that if a flaw is found, many hours of

H ugh Davies, director of client solutions at Optical Metrology Services (OMS), discusses how the latest internal weld inspection tools are helping oil and gas companies to verify the quality of risers, fatigue- critical and CRA-clad pipes, as well as curved pipes and manifolds.

One of the limiting factors in the lifespan of a pipeline is corrosion. 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. Prior to the development of the OMS WeldChecker™ internal weld inspection system, methods of examining the quality of internal welds in detail, from both a visual and a measurement perspective, have been inadequate and unreliable. A considerable gap has existed in the technology available for measuring the critical features of CRA welds such as HiLo (joint misalignment), weld height, width, and lack of penetration or fusion.

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TUBE PRODUCTS INTERNATIONAL November 2014

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