ASTM A967 vs. ISO 16048

Hello All,

I got some questions regarding ASTM A967 and ISO 16048.
I made a simple comparison table for both standards.
Could someone help me to clarify them?

https://drive.google.com/file/d/1HS_3CioZQvCENJlTQCW6PBcmJuFLSz2P/view?usp=sharing

1. Why is ASTM A967/967M-17 allowed pickling duration up to 45 minutes where as ISO 16048 only allows 30 minutes?
I know the parameters on both standards are "recommendations" not mandatory and they can always be adjusted by the passivation supplier.
But wouldn't there be more quality risks caused by longer pickling duration (e.g. hydrogen embrittlement for 400 series)?


2. Do we still have to pay attention on hydrogen embrittlement for 400 series stainless steel parts in pickling process (even they’re already shot-peened before pickling)?


3. In ISO 16048 table 1 footnote b, it says “For fastener manufactured from soft annealed and ground C1, C3, and C4 raw material only a shot-peening may be necessary”, but such requirement seems not on ASTM A967?
Does it mean that we don’t have to check if shot peening is done in the audit when product is passivated per ASTM A967?


4. Why would ISO 16048 says “Passivation shall be verified by the manufacturer's quality assurance system. There's no known reference test method for passivation.”? Does it mean supplier can use simple visual check as acceptance inspection after passivation when there's no additional inspection requirement mentioned on the purchasing order?


5. There’s no restriction for different ground or grade of stainless steel when using citric acid for passivation in ASTM A967, is it because citric acid is mild acid and would cause less harm on all types of stainless steels?