Extending pitch cylinder lifetime on Siemens SWT-2.3-93 at Rødsand II

Background

Rødsand II is an offshore wind farm operated by RWE, comprising 90 Siemens SWT-2.3-93 turbines commissioned in 2010.

After 14 years of operation, the pitch system began to show signs of hydraulic degradation.

Oil leakage developed across multiple pitch cylinders, making replacement necessary to maintain stable and predictable turbine operation.

The challenge

Original pitch cylinders delivered in 2010 were based on a design introduced in 2001, with only limited updates over time.

While sufficient in earlier years, long-term offshore exposure led to wear patterns not addressed in the original configuration.

RWE’s objective extended beyond replacing leaking components. The goal was to ensure that the next generation of cylinders could operate reliably toward the 30-year end-of-life target, with minimal O&M intervention.

Achieving this required a design update based on accumulated operational experience rather than a like-for-like replacement.

Initial assesment

Platform history showed a clear correlation between leakage and cumulative operating hours rather than isolated failures.

Drawing on more than 10 million operating hours, RWE pursued a solution reflecting how the SWT-2.3 platform performs over extended service life.

Focus was placed on combining application-specific insight with proven experience in long-life pitch cylinder design.

Technical approach

RWE selected United Wind and LJM as partners for the upgrade, combining platform knowledge with over 30 years of experience in pitch cylinder design across Siemens Gamesa and Vestas fleets.

A new long-life version of the SWT-2.3 cylinder was developed. The design maintains the same fit, form and function as the original A9B configuration, ensuring compatibility with existing interfaces and installation procedures.

At the same time, upgraded surface treatments and sealing technologies were introduced to extend durability under aging turbine conditions.

The engineering team developed a solution that would enable up-tower repair rather than a full replacement of the complete cylinder.

Execution

The exchange campaign began in 2024 and is scheduled for completion in 2026.

In addition to supplying cylinders, United Wind supported the campaign with team training and technical guidance, ensuring consistent handling and installation throughout the process.

Execution was structured to allow systematic offshore replacement while maintaining operational predictability.

Results

The upgraded cylinder design aligns with the remaining service life of the turbines.

Introducing improved surface and sealing technologies reduces the need for repeated interventions as the turbines continue to age.

The campaign supports stable long-term operation while limiting future maintenance intensity.

Key takeaways

Long-serving turbine platforms benefit from design updates based on cumulative operational experience.

Fit, form and function compatibility reduces risk in large-scale offshore exchange campaigns.

Structured execution is essential when replacing critical components late in a turbine’s lifecycle.

Closing

Long-term performance depends on how well solutions reflect real operating conditions.

Combining platform insight, component expertise and structured execution makes it possible to move beyond repeated replacement and toward lasting improvement.

In practice, that leads to more predictable operation—and less energy lost over time.