|
43098
What Passivation Process is recommended
for 3156 SS
++++++
We're currently going though a process of changing suppliers on a
axle shaft used on a pool cleaner. Our dwg. calls for the shaft to be
passivated by does not specify what specific process to use. I'm
debating between my purchasing department and engineering rather the
passivation process used by the supplier should be included on our
dwg. The Engineer in charge of the project thinks this is not
necessary since this is just a cleaning process.
Reading over a bunch of articles I learned passivation is not only a
cleaning process which make me concern about rather the supplier is
using the optimal (correct) passivation process for the
application.
The shaft is made out of 316 SS and our supplier is recommending to
use QQ-P-35, Type VI to passivate the parts.
Is this passivation spec recommended for the application, thinking
the part is expose to chlorine environments and temp up to 85ºF
Luis A. Gonzalez
pool products - Sanford, North Carolina
++++++
Yes.
QQ-P-35C [link is to spec at TechStreet]Type VI is
recommended or you could use ASTM
A967 [link is to spec at TechStreet] and Citric
Passivate.
Both types if done properly will "passivate" the stainless.
Bill Grayson
metal finishing - San Jose, CA, USA
++++++
Passivation will improve the resistance to the chlorine-containing
environment. The less resistant Fe & Ni atoms are selectively
leached away, creating a transparent chromium oxide layer about 20
Angstroms thick. Of importance, any iron (carbon steel) contamination
from the mfg. process which would otherwise rust is removed.
For properly selecting the passivation process, see QQ-P-35C or ASTM
A967. Type VI (Nitric 2 in A967) is suitable for 316 SS. Consider the
heated citric acid passivation solutions described in A967 and
available as CitriSurf products from
Stellar Solutions.
|
Ken Vlach
- Goleta, California
|
|


 |