Engineering news
The FSWBot (Friction Stir Welding Robotic Crawler) could “revolutionise performance and safety in industries around the world” by enabling several repair technologies without requiring pipeline shutdown, claimed developers Forth Engineering.
Sponsored by Innovate UK, the Cumbria company is working with TWI, J4IC, Innvotek and LSBU to develop the machine.
The consortium aims to integrate several technologies including friction stir welding, milling, patch deployment and ultrasonic non-destructive testing (NDT). Friction stir welding is a solid-state welding process which generates enough frictional heat to soften or plasticise metal without melting it, allowing components to be forged together at the joint line.
The system aims to demonstrate that a patch weld can be made in steel pipe under oil, and that a representative FSW system can be made small enough to operate in a 36 inch (91cm) diameter export pipe.
The FSWBot is envisaged as a five- or six-segment ‘pig’ vehicle that will be inserted at the production end of a pipeline and travel with the oil flow to a pre-designated spot for repairs. One segment will carry the FSW machine and a steel patch dispenser, with other segments carrying the navigation, control system, communications, NDT and power storage and generation payloads.
On entering a pipe segment containing pre-identified defects, the FSWBot will stop, then slowly advance until the FSW system is in place over the defect. It will then lock itself in place and confirm that it is correctly located to perform the repair.
An onboard turbine in an internal duct will harvest energy from the oil flow within the pipe to augment power cells carried on the system, with the duct providing through flow in the pipe.
Once energised, the FSW unit will use a milling tool to cut away the corroded area and prepare a pocket in the pipe wall into which a steel patch can be placed. It will then weld this patch in place and use the milling system again to ensure that the patch is flush with the pipe wall.
The machine will then use NDT to inspect the weld before unclamping and moving downstream to repeat the process on any further defects.
Solving challenges
“The tools we have developed over the years have been for, and used by, Sellafield, to successfully solve challenges in the nuclear industry. So our technology is tried and tested in harsh environments,” said Forth managing director Mark Telford.
“There’s a fantastic opportunity for other businesses and organisations in the UK and across the world, whether that’s other nuclear operations, or oil and gas, renewables, and perhaps areas we haven’t even thought of, to make use of that technology, and to share their challenges so we can develop the FSWBot in ways to help them.”
If development of the machine is successful, it could be enhanced to carry out more repair and fabrication tasks.
The project is due to be completed by the end of January in 2021. It will be presented at the British Manufacturing and Fabrication in the Offshore Energy Industry event in Aberdeen on 27 November.
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