Fatigue life and paint coating

[Engineer Gabo]

Hi,

For some time I am puzzling about the subject of fatigue life and painted coatings.
In some standards the influence of the environment is having a large impact on the fatigue life.
For example the standard FEM 1.001 (commonly used in crane design) gives a large factor for materials that are corroded by sea water.
Even the corroded by fresh water are relatively large.
As far as I know is most of the fatigue life depended on the crack initiation. Corrosion of the intrusions and extrusions blocks moving of these slip planes and increase the forming of a microcrack. With that in mind, preventing the surface of getting corroded would give a much more longer lifetime of the part.

Can these corrosions factors been set to 1 or neglected given the part has a good painting system (with also enough lifetime, inspections, maintenance, etc)?
Are there any sources that give indications about this?

BR,

Gabo

 

[MikeHalloran]

The answer depends on the nature of the product, the consequences of failure, and the various AHJs which might become interested.
You have so far revealed none of that information.


Mike Halloran
Pembroke Pines, FL, USA

 

[metengr]

You would need to review the specific design code to determine if surface condition or protection provides a benefit toward design fatigue life.

 

[MintJulep]

Because paint never gets scratched, chipped or otherwise damaged....