• In: Training | On: Jul 24, 2020

Wind Turbine Structural Steel


Can S355 be Weld-Repaired?

Today’s snippet discusses the steel needed for wind turbines, as well as necessary repairs welds, and code adherence.



High strength S355 structural steel

Many WT structural components are made from S355 structural steel.

The designation represents a Yield strength of 355MPa (this reduces slightly as sections get thicker than 16mm)



Is it susceptible to cracking?

If it is correctly rated to -20 DegC, then it has adequate resistance to brittle fracture down to that temperature.

Be careful though; there are cheaper grades available that are only rated to 0 DegC or +20 DegC.

Remember that all grades are still susceptible to fatigue cracking near welds and stress concentrations.


Can S355 be weld-repaired?

Yes. Codes such as BS EN 10025 limit the allowable Carbon Equivalent to a level that is welded, providing proper WPS/PQRs are used.



Here are some important questions for WT inspectors:

• Have site repair welds been welded fully to code (WPS/PQRs etc)?

• Do repair welds meet code visual acceptance criteria (fillet size, linear indications, leg length, profile etc)?

• Is there evidence repair materials meet the correct impact temperature rating for the grade (e.g. -20 DegC)?




If you have any questions about the Wilkinson Coutts Wind Turbine Inspector Cert, contact Paul Wilkinson or Craig Coutts via these two emails:






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