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Time now to prepare for warranty deadlines, says maintenance and repair specialist

Thu 22 Nov 2018 by David Foxwell

Time now to prepare for warranty deadlines, says maintenance and repair specialist
Carl-Rasmus Richardsen: “inspecting turbines takes time and there are large number approaching the end of their warranty period”

Turbine maintenance and repair specialist Deutsche Windtechnik says asset owners need to prepare now for the significant number of offshore wind turbines in German waters that will soon reach the end of their warranty period

At the end of 2019, a significant number of warranties on offshore wind turbines will expire, meaning operators need to subject installations to a comprehensive inspection to determine the condition of their turbines and assert possible claims against manufacturers. Not to do so before the warranty expires could leave them open to bearing the costs of repairing or replacing components.

Warranties on turbines in two German and one British offshore windfarms in the North Sea will expire in 2019. But crunch time is really approaching for the turbines in no less than eight different windfarms in the German sector of the North Sea in 2020 and two more in the UK sector, along with one in Dutch waters. 2020 also sees warranties on the turbines in another German windfarm in the Baltic expire.

Speaking exclusively to OWJ, Deutsche Windtechnik Offshore and Consulting managing director Carl-Rasmus Richardsen said operators need to take steps now to minimise the potential cost of maintenance and turbine downtime after warranties expire. “The most important thing is to start early and not start this process too late,” he said. “Key components such as blades, main bearings and gearboxes all need attention in good time if an operator is to avoid unnecessary expenditure.”

If an offshore wind turbine suffers an unexpected problem it can be costly to repair, said Mr Richardsen, not forgetting the cost of the downtime. “Every operator needs to ensure that turbines are operational for as long as possible and identify deficiencies and detect failures in critical components within the warranty period,” he said. “Effective warranty claims are an essential part of minimising maintenance costs.

“Inspection prior to the end of the warranty period is essential,” he told OWJ. “An independent provider of inspection services such as Deutsche Windtechnik can provide a comprehensive overview of the condition of an operator’s assets or focus on individual system components. It is essential that this kind of condition assessment is completed no later than three months before a warranty expires if an operator is to submit and enforce claims in good time.”

Mr Richardsen explained that Deutsche Windtechnik had undertaken a number of end of warranty inspections in the last 12-18 months, not least on behalf of market leaders such as Ørsted.   

Deutsche Windtechnik has used a range of techniques to assess the condition of onshore turbines for clients for a decade or more, including visual inspection and oil analysis, and is now applying the same techniques offshore. One of the most useful is non-destructive inspection using an endoscope, which has provided especially useful when assessing the condition of a generator.

Techniques such as video-based endoscopic inspection are also widely used to access components without first having to disassemble the surrounding structure. The advantage of using this technique is that endoscopic inspection can detect unexpected degradation of components such as main bearings prior to a warranty expiring.

As Mr Richardsen noted, an end of warranty inspection is also essential for deciding how assets are to be serviced and maintained for the remainder of their design life.

Some owners will choose to continue long-term turbine OEM partnerships because of a perceived lower risk, but others will prioritise taking turbine maintenance tasks inhouse with reduced OEM involvement, which reduces costs, and appoint an independent provider to undertake surveys.

“If an owner/operator doesn’t have the required knowledge and experience inhouse to undertake inspections they need to appoint a competent third-party company,” said Mr Richardsen, “do so in good time and choose a company that has the requisite expertise and background, which we have with our many years of experience inspecting turbines onshore and offshore.”

Ideally, the process of planning inspections would enable them to be carried out in the summer months, when inclement weather is less likely to have an adverse effect on offshore work. If a third-party is appointed to carry out inspections, sufficient time needs to be built into the process to enable that party to assess its findings, compile a report, provide recommendations and work with the OEM and windfarm owner to generate a plan for any repair work that needs to be carried out and plan ongoing maintenance and inspection.

With so many turbines in the German sector of the North Sea and in the Baltic approaching the end of their warranty periods, the time is now, Mr Richardsen concluded.

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