The UK's The Welding Institute (TWI) has started a new project to advance the decommissioning of offshore structures thru use of remote underwater laser cutting.
Over the next 30 years, some 600 fixed steel structures and 3000 pipelines will need removing from the North Sea.
In order to improve the flexibility, speed, and reliability of the process, TWI is developing a low-cost, high-speed, flexible laser cutting solution that can be deployed remotely to avoid the need for divers.
The project will see the development of a prototype tooling system alongside underwater laser cutting technology that will be effective for cutting 50mm thickness of mild steel at depths of up to 100m.
When the technology and processes are in place, the SubSeaLase capabilities can be developed towards a post-project use.
TWI says the system will need to be flexible enough to cut 50mm steel and 100mm concrete structures remotely without geometry limitations, while the use of a non-contact laser process will eliminate the risk of mechanical jamming, thereby minimizing down-time.
Not only will this new process be four times faster than existing underwater cutting technologies, but it will also reduce costs by lowering the days at sea required to complete a job, says TWI.
SubSeaLase will also be safer than existing methods by removing the need for divers due to the deployment of the ROV mounted with an underwater cutting head and fibre-delivered laser source and gas compressor, which will remain topside.
The unmanned operation will not only be safer for workers but, because it doesn't require the use of chemicals, flammables, or explosives there will be low secondary waste, which will mean a more environmentally-friendly solution.