Figure 78 Technicians carrying out foundation inspection and repair works, courtesy of Muehlhan.
Function
Foundation inspection and repair identifies and addresses corrosion and structural problems above and below the water line.
Who supplies them
Suppliers include CWind (Global Marine Group), Deutsche Windtechnik, Fugro, Global Wind Service, Mistras, Offtech Wind and Strainstall (James Fisher).
Key facts
Maintenance consists of visual inspections, non-destructive testing (NDT) and sea bed survey work with remedial service work completed when required.
Inspections focus on structural integrity, lifting, safety equipment, corrosion protection and scour protection.
Inspection work is managed by the wind farm owner, although is often subcontracted to a specialist third party provider.
Routine surveys are likely to be undertaken in the first two years but thereafter on a five or ten year cycle. Surveying the status of the protection installed to prevent sediment erosion, where the turbine foundation meets the sea bed (scour), can be carried out by side-scan sonar from a survey vessel or by using a ROV.
Regular inspections are required on secondary steelwork such as ladders, gates, grills and platforms. On some sites, cleaning is needed to remove sea bird guano, which can be a serious health and safety hazard.
Surface inspections and surveys include monopile internal inspections of the grouted or bolted connections and splash zone inspections. Activity needing subsea operations may include infrequent structural and J-tube cathodic protection inspections and weld inspections and can generally be carried out using ROVs.
Diving is required only in exceptional circumstances and efforts are being made to maximise the use of safer, remote techniques.