Differences between MIL-S-5002 Type III and QQ-P-35 Type VI Process

A. Dattatreya,
First, you can read both of these documents for yourself at the website http://assist.daps.dla.mil/quicksearch/

If you look at MIL-S-5002, the Stainless Passivation section essentially says little more than "in accordance with QQ-P-35", hence I expect MIL-S-5002 Type III is meant to mean QQ-P-35 Type III. This is not uncommon, I have spoken to many customers who have been asked to passivate to some semi-obscure military spec that in the end directs right back to QQ-P-35.

No doubt the reason for this change is your customer finally noticed that Type III was removed from QQ-P-35 with the C revision in 1988. Since then QQ-P-35C has itself been entirely canceled by the US government and superseded by ASTM A967 and AMS2700.

A. Dear Dattatrey,

Ray is absolutely right. Except, replacement for QQ-P-35 is AMS2700 and not ASTM A967.

Looking to the reference specs, it seems aerospace applications. In this case the supplier could be an approved a supplier having access to these specs. Both these specs gives the process details. In case of aerospace applications AMS2700 latest version C must be complied, since your customer is asking for QQ-P-35.

A. A 967 most definitely is one of the replacements for QQ-P-35. QQ-P-35c was replaced with ASTM A967 and AMSQQP35 [canceled] for aerospace, AMS-QQ-P-35 was later replaced with AMS2700.