Grinding hide small cracks?

[Christo_AU]

Hi All. I am investigating damage done to some steel brackets which connect a shipping container to four screw jacks used to level it. I have never been involved with the investigation of damaged steelwork before.

I want to confirm that there are no cracks at the welds using dye penetrant. However, the brackets are painted. I assume the paint will have to be removed by grinding to expose the welds below.

Is it possible that the grinding process might hide the cracks covering it with a thin layer of steel? (Similar to a burr on a knife. I am thinking malleability)
Is it possible that the grinding process might hide the cracks by filling it with paint swarf?

Thanks in advance

 

[MintJulep]

Yes, the paint must be removed.

Yes, "grinding" or other aggressive cleaning process can smear metal over a crack.

https://www.nde-ed.org/NDETechniques/PenetrantTest/Principles/liquidpi.xhtml

 

[TugboatEng]

You may consider magnaflux as it can detect shallow cracks below the surface.

Your structure is likely a fairly ductile. I wouldn't expect cracking without significant deformation.

 

[lucky-guesser]

Gentle sandblasting will remove the paint without distorting the underlying metal. And a small air gun is cheap.

 

[Christine74]

Grinding/wire-brushing prior to PT examination is not at all uncommon. See this previous thread:

https://www.eng-tips.com/viewthread.cfm?qid=292455

-Christine

 

[Christo_AU]

Thanks all for the feedback, much appreciated.