75% savings on bolting inspection costs

As wind turbines increase in size and their locations, particularly offshore, become increasingly remote, the labour times associated with bolt inspections are in turn becoming cost prohibitive. Reducing the need for site visits to carry out non-essential maintenance therefore provides an opportunity to make significant cost savings for turbine service teams and operators.

Typical inspection of standard bolts using hydraulic tooling may take as much as 40% of an entire maintenance plan. Through the application of new technology, the requirement for this type of inspection can be virtually eliminated.

By using remote monitoring technology, the load in each fastener can be recorded and transmitted ashore. The product experts at James Walker have developed RotaBolt Connect, which is set to revolutionise maintenance regimes, particularly where critical bolted joints are difficult or costly to access due to their location or operational environment, such as onshore and offshore wind turbine installations. This IoT solution can be utilised with digital twin connectivity to optimise performance.

In the case of RotaBolt Connect, the movement of a strain-gauge pin is measured electronically and a multi-point calibration process then calculates the load in each bolt.

The resulting bolt tension value is transmitted directly to a local phone or tablet during installation where a real time load reading, colour coded as a simple traffic light display, can be viewed to show the point at which the bolt reaches its design tension. Once activated, the RotaBolt Connect then continues to monitor and report on bolt tension, sending data to a local transceiver for onward transmission via GSM or Ethernet cable to the ‘cloud’. Additionally, data output can be modified for use with existing SCADA systems.

Checking the system via an online dashboard simplifies the maintenance planning process, allowing engineers to stay ashore without the requirement for a full bolt check and tightening schedule - only the bolts that need tightening go onto the list of maintenance tasks, therefore achieving the 75% potential saving in bolt inspection costs.

Outside of the obvious benefits to maintenance programmes, operators and manufacturers of turbine structures and key components are also being attracted to the monitoring system concept for its capability to provide data with ease and without the need to install, maintain and check specialised monitoring equipment on site. Additionally, health and safety benefits can be realised through less time at sea and the removal of the need for hydraulic tools. With less time required to be spent on bolt inspection related tasks, productivity should also be improved.