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20:22 May-25-2009

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
Stainless steel pre-penetrant etch

A vessel of 304 stainless has been garnet-blasted as preparation for painting. Dye penetrant is now required of the vessel shell. Any info about the effect of garnet blast on 304 (or similar) and which etchant should be used would be greatly appreciated.

Looking for external Chloride Induced SCC. Indications found on painted surface with Eddy Current which does not give any characterisation or depth info. Further investigation required for confirmation of these indications. Thinking of 45 degree shear wave from inside if access possible, if not 70 degree (no 80 degree or creep probe) from outside. Material 53mm thick.

Thanks

Nigel


    
 
17:07 Jun-15-2009

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1094
Re: Stainless steel pre-penetrant etch In Reply to Nigel Armstrong at 20:22 May-25-2009 (Opening).

Hi All

For completeness, the vessel owners opted for internal encoded Phased Array 45 degree linear inspection of the outer near-surface areas already highlighted by eddy current. High amplitude crack-like responses were obtained plotting out as extremely close to the outer surface (1 to 10mm).

A susbsequent nital etch of those areas followed by a red solvent removable penetrant revealed strong indications, some of crack-like nature. I am back in the UK now, but I shall try to obtain images to post here.


    
 


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