A standard 1.5-megawatt wind turbine stands over 320 feet tall (including blades) and weighs over 164 tons. Protecting wind turbine foundation bolts from the effects of corrosion is of utmost importance.
A lot is written about the design and maintenance of turbine components ... products to reduce wear and tear in the gears, how to control the atmosphere in the nacelle and tower to minimize corrosion, coating systems for the structure and blades ... the list of ASTM and ISO standards that apply to the design and manufacture of these complex structures is a long one.
However, there is very little information available regarding the maintenance of wind turbine foundation bolts, also known as anchor bolts. A standard 1.5 megawatt wind turbine tower is well over 200 feet high (with its blades making it more than 320 feet), supporting a combined weight of 56 tons for the nacelle and 36 tons for the blade assembly. The tower itself weighs another 72 tons. The entire 164+ tons is anchored to its foundation by a series of bolts set in concrete.
Once the foundation is complete, the first section of the tower is lowered on to the bolts and secured, then the rest of the turbine is assembled above. The bolts have to be tensioned accurately to prevent any movement on the base as the tower flexes in strong winds to reduce foundation deflections from high wind loadings.
So, the condition of the bolts and nuts is critical to the long-term survival of the tower. Yet many bolts are left exposed to the elements and are extremely vulnerable to corrosion. Bolt tension issues have been identified as a cause for failure in turbine collapses, as have bolt failures from the effects of corrosion - particularly galvanic and crevice corrosion. And, if the nuts and threads corrode, retensioning the anchor bolts may be impossible, further threatening the structure.
While a range of solutions exist for post-construction remediation and prevention of corrosion damage to exposed bolts, many have limitations around size and maintenance requirements.
How to Protect Wind Turbine Foundation Bolts from the Effects of Corrosion
NEWS & INFORMATION
Bolt caps have to stay in position to work, they usually have some kind of friction fit mechanism to maintain their seal with the base but this is not always effective. Because Enviropeel is spray applied, it moulds itself around every thread making it impossible to dislodge yet easy to remove, if required, by simply screwing it off.
And, of course, Enviropeel is designed to be effective against galvanic and crevice corrosion, containing its own active inhibitors. So, if corrosion is already present in the bolts, Enviropeel not only prevents further deterioration but will also condition the nuts and threads so that they can easily be adjusted for maintenance.
Compare Enviropeel with protection using a wrapping system - as long as the wrap stays intact, it will provide a barrier to water ingress but nothing else - and, it cannot be removed for inspection without having to be completely replaced whereas, with Enviropeel, it can be removed & replaced.
Its the perfect solution!
The Enviropeel solution is simple.
Anchor bolts can vary in length, but the exposed threads are always several inches long, so providing the correct size of bolt cap can be a problem. Because Enviropeel bolt applications will fit any size or shape of bolt, it provides a simple, one-size fits all solution.
