A first for the oil industry

Optical Metrology Services Ltd (www.omsmeasure.com) has completed an on-site internal weld inspection survey for a major oil company. This is the first time that a combination of laser, video and ultrasonic inspection methods has been used in a production environment to inspect the profile of root welds on oil and gas pipes.
Carried out by OMS’s US operation,the survey covered the full range of weld features, including crown height, under-cut, porosity and burn-through. Moreover, inspections had to be carried out at temperatures up to 250°C.
Richard Gooch, director of technology at OMS, says: “On this project, the pipes on the modular valve manifold system were almost entirely lined with a special corrosion-resistant material, so our team of three inspectors had to make sure that they didn’t overheat these coatings while carrying out inspections. On average, it was taking the customer around four days to complete a root weld pass, and if there were flaws in a weld, it would have to be repaired or cut out. Our inspectors carried out their inspections immediately after the hot pass, with the laser- and video-based inspection taking about 10min to complete.
“The modular valve manifolds are mounted on 30ft skids and are critical junctions within oil or gas pipelines. Our inspection tools were able to pass round 90deg and 33deg bends in the pipework, as well as inside the valves themselves. In order to do this, we designed a special laser-based measurement system that incorporated a slide rail, stepper motor and optical laser sensor. This allows us to push the tool through the pipes in 0.5mm steps to inspect the profile of the welds.”