In offshore wind, there’s always a strong focus on blades, towers, and electrical systems; but tucked away in every turbine are pressure systems that are easy to overlook. These might include hydraulic accumulators, compressed air receivers, or other high-pressure systems used for pitch control or maintenance equipment.

Under the Pressure Systems Safety Regulations 2000 (PSSR), any system containing relevant fluids under pressure must be managed safely. One of the key legal requirements is the need for a Written Scheme of Examination (WSE) before the system is used. It’s not just a tick-box exercise, it’s a practical way to make sure people aren’t exposed to the serious risks that pressurised systems can pose.

What is a Written Scheme of Examination?

A WSE sets out what equipment needs to be examined, how often, and in what way. It’s prepared and certified by a competent person, usually an engineer or inspection body authorised to assess pressure systems. At HSEQ-360 Limited, ours are authored by a Chartered Engineer, and peer reviewed internally by Chartered professional in Health, Safety and Quality. We’re also ISO certified by a UKAS-accredited certification body to author such schemes. For several years, we’ve authored such schemes for all of Ørsted’s UK offshore windfarms, and have recently been retained for a further three years 

A good WSE should cover:

  • Exactly what equipment is included, such as vessels, pipework, valves, and safety devices.
  • How and when each part will be examined, including inspection methods.
  • Maximum time intervals between inspections, based on how the equipment operates and the risks involved.
  • Who the competent person is, and their responsibilities for approving and reviewing the scheme.

The WSE becomes the agreed plan for keeping your pressure systems safe throughout their service life.

Offshore wind. A unique challenge

For offshore wind farms, applying the PSSR can be trickier than onshore. The equipment may be relatively small, but the risks and logistics are much bigger.

  • Harsh environment – corrosion, vibration, and moisture all accelerate wear and tear. The WSE should reflect this by specifying shorter inspection intervals or additional checks.
  • Access and timing – you can’t just send an inspector offshore whenever you like. Weather, vessel availability, and technician schedules all affect what’s practical. A realistic WSE accounts for that.
  • Complex systems – in modern turbines, hydraulic or pneumatic systems are safety-critical for braking or blade pitch control. Deciding what counts as “pressure equipment” under PSSR can require some careful thought.
  • Frequent upgrades – when turbines are modified, repowered or re-equipped, the WSE must be reviewed. Even small changes can affect safety boundaries or protective devices.

Common mistakes to avoid:

Many offshore operators fall into the same traps when managing WSEs:

  • Treating the WSE as a static document rather than something that evolves with the asset
  • Copying a generic scheme from a supplier without tailoring it to site conditions
  • Forgetting to involve the competent person early enough in the design or commissioning phase
  • Failing to link WSE findings to maintenance or integrity management systems

Each of these can lead to gaps in inspection, unnecessary downtime, or in the worst cases, enforcement action.

At HSEQ-360 Limited, we’ve supported several clients in offshore wind who wanted to tighten up their compliance with PSSR 2000. Some simple, effective steps include:

  1. Start before commissioning: don’t wait until the system is running to develop the WSE. Build it into your pre-start process.
  2. Use risk-based intervals: base examination frequency on system condition, not the calendar.
  3. Be realistic about offshore access: make sure the WSE schedule aligns with vessel and technician availability.
  4. Keep the WSE linked to maintenance: inspection findings should feed back into your maintenance plans and reliability data.
  5. Review after modifications or incidents: any significant change to the system or its operation should trigger a review of the scheme.

Why it’s worth getting right

Beyond legal compliance, a strong WSE brings real operational benefits. It helps reduce unplanned downtime, extends equipment life, and supports safe, predictable maintenance planning.

More importantly, it demonstrates to regulators and stakeholders that safety and integrity are built into your operations, not added as an afterthought.

At HSEQ-360 Limited, we help offshore wind clients develop and review Written Schemes of Examination that are practical, compliant, and tailored to real-world operations. Whether you’re commissioning a new turbine or reviewing existing documentation, we can help ensure your WSE works for both your people and your assets.