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Innovation Challenges

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Innovation Challenges

Remote Bolt Torqueing


ORE Catapult Bolt Torque Innovation Challenge

Offshore wind turbines are full of bolted connections.

In particular, towers are often made in sections that are bolted together with hundreds of large bolts, requiring specialist equipment to torque or tension each one to the required tightness. Approximately 10% of the bolts in a set will be checked and tightened during an annual service as this is a time consuming task, and relatively low risk unless bolts are discovered to be loose. For example, if there are 100 bolts in a ring, the first inspection will check every 10th bolt, the second inspection will check the next one along from each of those previously checked bolts. This is to ensure that a representative sample has been examined from the set to provide sufficient confidence that the joint remains within the necessary tolerance.

The bolts in wind turbines are tightened to specific values depending on the size, length and grade of the material. Over tightening can cause the bolts to break during tightening or operation, while under tightening can lead to the bolts becoming loose during operation. This task is performed repeatedly over the lifetime of a wind turbine as part of the annual service. Bolt tightening is currently performed manually using either torque or tensioning tools, which are often hydraulically operated and can be heavy and cumbersome, especially for bigger bolts such as those in the tower. It is a very repetitive, intensive task where associated costs are high.


The challenge is to develop an innovative and cost-effective solution that addresses one or more of the limitations associated with the manual inspection and re tightening of bolt tension / torque (as described above). The current method is expensive, relying on the use of several personnel (technicians) and manual manoeuvring of heavy equipment. A crew transfer vessel is also required to transport personnel and equipment to the site from shore, adding further cost and logistical complexities.

Solutions must seek to minimise or completely remove the need for human intervention to perform bolt inspections, for example in the use of robotics or remote monitoring systems. It is important to be able to evaluate the bolt tension whilst in-situ. This means that the solution must be able to operate offshore, and potentially at height. Solutions that can be operated remotely or automatically would be beneficial. Ideally the solution would be remotely operated to minimise HSE risks and human intervention.


Solutions must be able to be operated safely and reliably in offshore conditions with:

  • Average wind speeds up to 15m/s;
  • An ambient temperature 0-400C;
  • Heights of 100-200m above sea level;
  • Distances up to 25km from shore, ideally up to 40km.


To be attractive, new solutions must significantly reduce the costs associated with manual bolt torqueing inspections. For a typical 6MW offshore wind turbine, current industry practice is to check 10% of tower bolts at each 12-month service interval. Currently the time and costs associated with manual bolt inspections include a minimum requirement of two technicians, vessel transfer from shore to the offshore wind turbine, lost energy generation as the turbine must be shut down to gain access and the time spent doing a repetitive, labour intensive task that could potentially be more efficiently spent on more critical and complicated service tasks. An ideal solution should aim to achieve a 50% overall improvement on cost and time of inspection.

Solutions must seek to minimise or completely remove the need for human intervention to perform bolt inspections.


The current estimated UK market for a successful solution will be in the region of £20m p.a. with a significant export market.

In the UK, there are 2020 operational offshore wind turbines (September 2018), with a further 2470 operation in other European markets. The global market totals 5046 turbines. Growth is expected to continue in all key markets, across the whole operations and maintenance market (O&M). In Europe, the O&M market is estimated to be worth between £1bn and £1.42bn per annum.

Do you have a potential solution?

Our Innovation Challenges team are waiting to hear from you!

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