Fatigue life and paint coating

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