Turbine Oil Filled Traffo Unit Repair
The oil filled traffo units installed on the turbines when being regularly maintained had, in some cases developed leakages due to the turbines corrosive environment offshore. The thin gauge steel used made it additionally difficult to repair as at only 0.8mm thick it is very much a high spec technical welding task.
We were originally asked to review the technical spec and provide 6 welders so adhering to previous WPS’s used by Siemens our welders all had to sit and pass quite specialist coding to BSEN standard.
Also, to go in line with our welding certificates we were all asked to attend specialist training with ‘Force Technology’ in Esbjerg, Denmark. For a 2-week intense course specifically designed to help with the task of welding on oil fitted transformers.
Once all training was complete we then joined our customer in the successful 2 year plus campaign. On the project we were not there to only weld we also integrated into part of a 3-man team to perform Retro-fit duties. This involved fitting, drilling, working under hot works, taking oil samples and other basic maintenance of the turbine/transformer.
The retro-fit project was completed at a number of major offshore wind farms located around the UK. Also, successful ad hoc re-active welding has also been completed at sites around the coastline of the UK as well.
It is not uncommon to hear that turbines move in the wind. It was discovered in 2014 that the Turbines installed at North Hoyle installation were moving a bit too much. As a consequence of these movements, seals were affected. This could have affected the integrity of the installation and the lifespan of the installation. So, inspections were undertaken to resolve the movements.
The customer approached GIBBS to execute and work to a designed cost-effective solution.
This involved fabrication of the designed items working to the highest standard confirming to BSEN 9606 and the DNV standard. Ready for installation offshore in the turbine.
Once offshore a 5-man team including confined space rescue team, an NDT engineer and 2 welders commenced works on the project which required a total of 10 operatives working to a rota.
The total time frame given for these works was 50-days per turbine with 29 in total to undertake these solution works. Within the 50 days GIBBS also managed weather condition working and other unexpected issues.
The project is over a number of years with monitoring being an important aspect. So far, the repair seems to have steadied the turbines which is what we are trying to do.
“If you have experienced anything like these problems. Our valuable skills and knowledge in this field can enable the solution to become a reality”