I am sure you will get some good replys here soon, here is plenty of SS experts!
In my personal experience, I also prefer to inspect the welds prior to any kind of acid cleaning or passivation.
If the welds has oxidation/sugaring in the root, it can be very hard to see after a chemical cleaning/passivation.
Another thing is, in case of heavy discolorration of the root, acid or passivation may not be the proper solution.
3.2
ASTM E-165
Annex A1
"A1.1 Choice of Cleaning Method"
"A1.1.1.8 Acid Etching--Inhibited acid solutions (pickling
solutions) are routinely used for descaling part surfaces.
Descaling is necessary to remove oxide scale, which can mask
surface discontinuities and prevent penetrant from entering.
Acid solutions/etchants are also used routinely to remove
smeared metal that peens over surface discontinuities. Such
etchants should be used in accordance with the manufacturers'
recommendations. Caution:
NOTE A1.1--Etched parts and materials must be rinsed completely free
of etchants, the surface neutralized and thoroughly dried by heat prior to
application of penetrants. Acids and chromates can adversely affect the
fluorescence of fluorescent materials."
That acid wash is effectively an etchant. The key will be to assure no residue remains.
I suggest you get the standard referenced here.
Regards,
Gerald
Sticky would not be the best prep for PT testing.
Id get some literature about PT.
Is this Code?