Ecological and economical: Corrosion protection systems in wind energy

Onshore and offshore wind turbines now provide almost a fifth of Germany's total electricity generation. That makes them the most important renewable energy source – with further growth potential. Especially in the offshore sector, there are additional, very favourable conditions for Germany: On the one hand, the North Sea and the Baltic Sea offer good and continuous wind conditions. On the other hand, there are large areas there where the depth of the sea is only 20 to 50 metres and which are therefore ideally suited for the cost-effective construction of wind farms. Profitable investments in wind energy also depend very much on trouble-free operation and an appropriate service life of at least 20 or, better, over 30 years. Efficiency and competitiveness cannot be ensured without adequate protection and continuous maintenance of the plants. The steel and cast iron components of wind turbines – such as tower segments, machine houses, shafts and hubs – require sophisticated corrosion protection in order not to be defective after just a few years.

Onshore corrosion protection

Steel Towers

SikaCor® and Sika®Permacor® corrosion protection systems provide long-term protection of steel towers with high-quality, matched products. The coating systems are based on modern binder resins, which enable low-solvent production. Priming coatings with active pigments and thick-layer intermediate coatings ensure a long-lasting corrosion protection, the top coats based on polyurethane meet the highest requirements for weather resistance and colour stability. Sika systems have proven their worth on more than 10,000 wind turbines over many years of service.

The main advantages:

  • Permanent corrosion protection tested up to the highest corrosivity category. Onshore: C5 high according to EN ISO 12944-6.
  • Fast curing enables short coating intervals and delivery times.
  • High-quality top coats achieve lasting colour stability and gloss retention.
  • Low emission by using very low-solvent coating materials
  • Matched repair systems for the revision of transport and installation damage

 

Below are some examples of coating systems:

 

COMPONENT CORROSION PROTECTION SYSTEM CORROSION PROTECTION TESTS TOTAL LAYER THICKNESS
Tower interior surfaces

1 x SikaCor®-2440 MF

1 x SikaCor® EG-5

C3 high 200 µm
Tower exterior surfaces

1 x SikaCor®-2440 MF

1 x SikaCor® EG-5

C4 high 240 µm
Tower interior surface

1 x SikaCor® NCG Base Coat

1 x SikaCor® EG-5

C4 high 240 µm
Tower exterior surface

1 x SikaCor® NCG Base Coat

1 x SikaCor® EG-5

C5 high 300 µm
Machine components from steel and cast iron

SikaCor® coating systems guarantee a long-lasting economical corrosion protection in the interior of nacelles. The cast iron and steel components such as hubs, base frames, generator carriers, rotor shafts, machine housings, etc. are protected from severe mechanical damage during transportation and installation. In later operation, the coating prevents corrosion, repels dirt and is easy to clean.

The main advantages:

  • Best protection during transport and assembly thanks to high mechanical durability.
  • Fast curing enables short coating intervals and delivery times.
  • Long-term corrosion protection by active pigmenting.
  • Environmentally friendly low-solvent product systems.

 

Below are some examples of coating systems:
 

COMPONENT CORROSION PROTECTION SYSTEM CORROSION PROTECTION TEST TOTAL LAYER THICKNESS

Steel and cast iron components

in the interior

of nacelles

1 x SikaCor®-2420 EMK

1 x Sika® Permacor®-2230 VHS 

C3 high 180 µm

1 x SikaCor® EG Phosphat Rapid

1 x SikaCor® EG-5

C3 high 180 µm

2 x SikaCor® EG Phosphat Rapid

1 x SikaCor® EG-5

C4 high 240 µm
Repair systems

Transporting and assembling the partly very heavy parts and components can cause damage to the corrosion protection coating. To repair damaged components, 1-component coating materials ensuring the highest possible corrosion protection and easy usage are used in the onshore area.

Below are some examples of coating systems:
 

SYSTEM TYPE LAYER THICKNESS CORROSION PROTECTION SYSTEM COLOR SHADE
Variant 1

Priming coat

Top coat

2 x 60 µm

1 x 60 µm

2 x SikaCor® Aktivprimer Rapid

1 x Sika® CorroTop NEU

beige yellow

RAL 7035, RAL7038

Variant 2 Repair coating 1 x 500 µm 1 x SikaCor® SW-1000 RepaCor® RAL 7035, RAL 1023,
black

Offshore corrosion protection

Offshore standards and testing methods

EXPOSED TO EXTREME CONDITIONS, corrosion protection coatings in the offshore sector must survive maintenance periods of at least 20 years. Comprehensive and specially designed norms, standards, rules and regulations, such as EN ISO 12944-9, the VGB-BAW standard or the NORSOK standard simulate these special extreme conditions and give operating companies certainty in product selection.

The requirements contained therein were the centrepiece of the cyclic aging test in the former international standard ISO 20340 illustrated below, which was completely incorporated into the revised EN ISO 12944, Part 9 and is part of this section of the standard.

 

Electromechanical test procedure according to ISO 15711 Method A

In this laboratory test, the disbonding of coatings used on offshore objects is tested for suitability and certification. Method A involves the use of a cathode protection system, which is monitored by means of potentiometer. The testing plates will be tested in artificial sea water using a cathodic protection potential of -1050 ± 5 mV Ag/AgCl/sin or exposed to Kalomel. The duration of this test is 25 weeks or 4200 hours. The test requirements are met if the disbonding at the artificial damage is less than 20 mm.

Korrosionsschutz Sika Deutschland: Windenergie zyklische Alterungsprüfung
Steel towers on the high seas

The Sika® Permacor® protective paint system is applied according to the highest standards of the corrosion protection. Due to a very high mechanical durability, the tower sections are already protected during transport and especially during construction.

The main advantages:

  • Durable corrosion protection under loads on the high seas. 
    Offshore: Norsok Standard M-501, system no. 1.
  • High mechanic durability
  • High-quality top coats achieve lasting hue stability and gloss retention.
  • Low emission by using very low-solvent coating materials
     
COMPONENT CORROSION PROTECTION SYSTEM CORROSION PROTECTION TEST TOTAL LAYER THICKNESS
Tower interior surface 1 x Sika® Permacor®-2311 Rapid
1 x Sika® Permacor®-2215 EG VHS
1 x Sika® Permacor®-2230 VHS
C5 high 260 µm
Tower exterior surface 1 x Sika® Permacor®-2311 Rapid
1-2 x Sika® Permacor®-2215 EG VHS
1 x Sika® Permacor®-2230 VHS
CX (Offshore) 280 µm
Steel foundation structures

The construction of offshore wind turbines is carried out mostly on steel foundation structures such as monopiles, tripods, tripiles and jacket constructions. These surfaces that are in permanent contact with seawater require a coating system that is extremely mechanically resistant in addition to the requirements for corrosion protection. SikaCor® SW-501 and Sika®Poxicolor® SW Neu meet all requirements and pass all tests. In addition, they are solvent-free or have a low solvent content and are therefore very environmentally friendly.

The main advantages:

  • Maximum corrosion protection for permanent sea water exposure and in the tidal zone.
  • Highly resistant to abrasion as well as mechanically sturdy
  • Suitable for an application in combination with cathodic protection systems (KKS)
  • 2-component epoxy resin coating, very environmentally friendly.
     
COMPONENT CORROSION PROTECTION SYSTEM CORROSION PROTECTION TEST TOTAL LAYER THICKNESS
Jacket
Monopile
Tripod
Tripile

2 - 3 x SikaCor® SW-501* / 
Sika® Poxicolor® SW Neu*

 

Norsok M-501, system Nr. 7

BAW: Im1 - 4

600 µm
*Optionally, for special requirements regarding the colour shade and the UV resistance, it is possible to apply Sika Permacor-2230 VHS as top coat.
Offshore repair systems

Detailed repair instructions are created for offshore structures for repairing damage to the corrosion protection coating. These are individually adapted to the initial protection system used and thus meet the high corrosion protection requirements. Furthermore, we have developed SikaCor® SW-1000 RepaCor for the protection and repair of existing structures, which can be simply applied under difficult conditions such as climate, weather and accessibility.

The offshore repair revolution

2-COMPONENT REPAIR FROM THE CARTRIDGE

In the cooperative research project “RepaKorr“, the project partners drew up the basic material-related, technical, conceptual and organisational principles for an “on-site repair” concept.

With SikaCor® SW-1000 RepaCor, our research department has succeeded in developing an abrasion-resistant, innovative 2-component coating material. It meets all requirements for the touching up or repair of (mechanically) damaged coating surfaces.

The main advantages:

USER FRIENDLY

2-component coating from the cartridge - low weight for the user

FAST

Curing in record time even under water, with just one work step. UV-resistant without additional top coat
 

SAFE

No waste, no emissions - solvent-free coating consists of 100% solids
 

Typical Application Areas

Steel Tower

Machine Parts And Attachment

Repair

Foundation Structures

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