Acid cleaning and passivating

Date 04-06-2009 05:26

I have been asked to dye check welds on 316ti-s/s. Some are lazer and others are manual. The concern I have is they are acid washing and passivating the welds before I inspect them. They are acid washing and then washing after with soap and water. My concern is if we are getting all the acid solution out of all the small holes and tight places. I seems to be sticky to the touch. Should I flush it good before I go any farther or check the welds before the acid washing ? Help !

By 3.2 Inspector (***)

Date 04-06-2009 07:26

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

By CWI555

Date 04-06-2009 20:10

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

By michael kniolek (***)

Date 04-06-2009 22:35

Sticky would not be the best prep for PT testing.
Id get some literature about PT.
Is this Code?