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18.01.2019 Offshore warranty — the use of video endoscopy is on the rise

Video endoscopies have been an integral part of the services provided by Deutsche Windtechnik for many years. During the last year and a half, the demand in the offshore sector in particular has risen significantly. One of the main reasons for this is the high number of wind turbines that will soon reach the end of their warranty period. However, video endoscopy inspections are also used in the course of general maintenance to test crucial components of a wind turbine. If initial damage is detected, case-by-case remedial measures can prevent consequential damage that may even lead to total failure.

Areas of application of video endoscopy

A video-endoscopic inspection is usually preceded by an evaluation of the CMS data (Condition Monitoring System, offline or online). If vibrational abnormalities are detected in the measured data, this may be caused by insufficient lubricants, fatigue, overload or foreign objects in the gearbox. If no other potential causes for the data abnormalities are found, then the gearbox should be subjected to a video-endoscopic inspection. Using a camera probe four millimetres in diameter, which is inserted through existing openings in the gearbox housing, all important components (especially bearings, shafts and tooth flanks) in the gearbox are visually inspected for damage. Clear indications of excessive load include standstill marks or running marks on the tooth flanks, pittings on the rolling surfaces, damage caused by foreign objects (abrasion) or even tooth breakage.

pitting on a gear tooth breakage
Figure 1: pitting on a gear                                                  Figure 2: tooth breakage
(Photo: Deutsche Windtechnik)                                     (Photo: Deutsche Windtechnik)

Results and service experience are linked in a meaningful way

Using the written and visual damage documentation, the specialists prepare an inspection report that includes recommendations for action. The many years of experience as well as the high number of video-endoscopic inspections that are carried out (approximately 300 video endoscopies per year) enables the Survey and Inspection Body of Deutsche Windtechnik to give a concrete assessment of the remaining service life of the component. The inspection report is therefore fundamental in deciding how to proceed. In many cases, a cost-effective maintenance measure will allow the system to continue to be operated without any concerns. If no video endoscopy is carried out, a large component may have to be replaced at a later date. Enormous costs for the operator are the unpleasant consequence.

Teams of experts and the latest technology form the foundation

This condition-oriented form of inspection is carried out by trained experts who always use state-of-the-art endoscopy equipment. In order to ensure the highest quality of work, employees are regularly trained, and the technical equipment is replaced at least every two to three years. The high-resolution camera, which was originally used in the medical field, provides 5X zoom and a real-time video feed. The user can also create still images.

Further contracts for Siemens 3.6 systems

The new year is starting off with another major contract for Deutsche Windtechnik Offshore and Consulting. OWP Butendiek GmbH, the operator of the wind farm of the same name, has signed a contract with Deutsche Windtechnik and is thereby responding ahead of time to the upcoming warranty end. Beginning in March, the 80 Siemens SWT-3.6-120 turbines at the Butendiek offshore wind farm will be inspected using video endoscopy.

Last year, the service teams of Deutsche Windtechnik's Survey and Inspection Body already carried out more than 300 video endoscopies on offshore wind turbines. Further inspections currently are planned in four additionally wind farms in 2019.

More information on this topic can be found in our infoletter or obtained in a personal conversation:

Stefan Marschner
Sales & Contract Manager Deutsche Windtechnik Offshore und Consulting GmbH