Repair of pitting corrosion in stainless steel 1

[mrmalcolm]

Is there any guideline for repair for stainless steel pitting, such as (1) if excavating pitting, what should be the ratio of diameter to depth of the excavation to ensure a smooth transition. (2) For deeper pitting, is it possible to use a non-metallic filler such as epoxy putty without excavation. (3) What is the pitting corrosion density of stainless steel, it is necessary to change the plate.

Thanks a lot.

 

[EdStainless]

You won't be able to fill pits in SS without grinding them open.
Pits in SS quite often have a small opening with a much larger internal volume.
With pitting attack it is common to have >95% of the surface fine but also to have holes through it.
At what point will holes impact your application?
Repairing in any manner will result in a life shorter than you got at first.
Epoxy repair is usually done for the entire exposed surface.
First grind all pits open and wash, then a light blast, base coat with a very thin epoxy, then coat with a very heavy build layer.

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P.E. Metallurgy, consulting work welcomed

 

[mrmalcolm]

Thank you for your reply.
I agree with your point of view. For the repair of stainless steel pitting, grinding or even welding repair may be the preferred method. The problem we encounter is that if the pitting is very deep, in order to ensure a smooth transition between the excavated hole and the surrounding area (the ratio of excavation diameter to depth is not less than a certain value), it may cause a large excavation area, resulting in a decrease in the thickness of the entire structure. So, for deeper pitting, can we fill it directly with epoxy without grinding, or directly excavate the pitting deeper without grinding the surrounding area (which may make the grinding edges sharp).
Intuitively, even if the pitting is deep, if the pitting density is small, it will not have a fundamental impact on the entire stainless steel structure regarding the impact of pitting on structural strength. However, we do not know how much pitting density may have a significant impact on the strength of stainless steel structures.


Thank you.

 

[0707]

glass fibers mixed with epoxy resins are commonly used as coatings in tanks.