The tower door weld, a lifetime extension check not to miss
The door cutout at the base of every tubular steel tower creates a stress concentration, and rainwater run-off makes the weld around it prone to corrosion. A small detail that deserves a close look in every lifetime extension inspection.
During any turbine lifetime extension assessment, one inspection is easy to overlook, the weld around the tower door cutout.
The removal of the door cutout material and differences in stiffness between the tower and door surround make this a high risk location for fatigue cracks.
Why this location matters
- Material has been removed from the shell, so the remaining section works harder.
- The stiff door surround welded to the thinner shell concentrates stress around the connecting weld.
Where water comes in
Rain landing on top of the door surround often runs around this weld, making it prone to corrosion. Coatings are also harder to apply and maintain at welds, where rough surfaces and tight radii leave thin spots. Corrosion at a highly stressed weld is exactly where fatigue cracks can start, so prompt repair of any coating damage in this location is essential.
What this means for lifetime extension
Left undetected, a crack in this location is a risk to safe operation in extended life, and to the case for extension itself. The check is quick and cheap, a close visual inspection of the weld and coating condition around the full door perimeter, with coating repairs actioned promptly and further investigation where damage or cracking is suspected.
If you are paying for a lifetime extension assessment, it is worth confirming this inspection is explicitly in scope. PowerVeritas ensures key checks like this are included in lifetime extension inspection scopes.
Photographs by PowerVeritas.