REWITEC™ arrests damage to wind turbine main bearings
RWE in the USA operates a fleet of GE 1.6MW turbines. A routine borescope inspection in 2019 revealed considerable micropitting on several main bearings within the turbine fleet. Micropitting can dramatically affect the reliability of a turbine should it be left untreated, so RWE opted to use REWITEC as a treatment for a number of turbines.
REWITEC GR400 was applied to seven turbines, all 8 years old and all with varying degrees of damage. Borescope visual inspections and surface analysis were carried out on the treated parts before and approximately seven months after application.
Impressions of the bearing surface were taken up-tower, using a REWITEC replica set, which could then be taken away for further analysis in the laboratory. Care was taken to ensure that the same part of the surface was analysed, so that a direct comparison could be made.
The impressions were then analysed using profilometry. The image below shows surface topography of the main bearing before treatment and approximately 7 months after application. It can be clearly seen that the presence of pits and cracks within the wear scar is greatly reduced after 7 months of treatment. The profilometer also provides surface roughness data which shows a significant reduction of up to 65% following treatment with REWITEC GR400.
Further, use of REWITEC can extend the lifetime of wind turbine assets
The results obtained above were fed into digital modelling tools and evaluated in collaboration with Sentient Science, an external engineering company. Sentient concluded that the surface roughness improvements obtained will lead to 7 years of extended turbine life in relation to wear related failure modes. Such results would help the turbine owner to fulfil the 20-year design life for their assets.
To this date, within the fleet of assets treated by RWE, there have been no main bearing failures due to wear related issues.