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ASTM A967 vs. AMS 2700? Which is the right passivation spec?

(2003)

Q. Did ASTM A380-96 go away, and ASTM A967-96 replace it?

My customer wants to put A380-96 on his print for standard passivation, but my plater tells me that he passivates to A967-96. What should I tell my customer?

2nd question, if I ask for standard passivation on imported product, what ASTM spec do you think I will get?

Thank you

Gene Prehatney
- Champlin, Minnesota


(2003)

A. First question: The current ASTM versions are A380-99e1 "Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems" and A967-01e1 "Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts".

It is relatively easy to modify a passivation process to satisfy ASTM A380 [link is to the practice at TechStreet] , and ASTM A967 [link is to spec at TechStreet] , and QQ-P-35C [link is to spec at TechStreet] and AMS2700 [link is to spec at TechStreet] (primarily, a little paperwork). Have the plater do so, and then certify to multiple standards. (Lee Kremer has pointed out that A380 is not a Specification, only a Practice).

Second question: A guessing game? "Standard passivation" is meaningless unless the standard is specified.

Ken Vlach
- Goleta, California  

Ken received a special
"Contributor of the Year" award
from finishing.com for his numerous
helpful and well researched responses

(2003)

A. As Ken says, ASTM A380 should not be used as a passivation specification, and QQ-P-35 has been canceled. The 3 consensus specifications used at this time, and that should be used for all specifications of passivation are:

ASTM F86 [link is to spec at TechStreet] for Orthopedic implants,
AMS2700 [link is to spec at TechStreet]for Aerospace,
ASTM A967 [link is to spec at TechStreet] for all other applications.
There are other in-house specifications for some companies.

A-380 has a lot of excellent recommendations on general cleaning etc. of stainless steel, but should never be used as a passivation spec.

AMS QQ-P-35 is being canceled in favor of AMS 2700 (at the moment it is version B)

You should never ask for "standard passivation" on imports. Always specify exactly what you want-- e.g., ASTM A967 01e, Citric 4 or AMS 2700B Nitric 1. If you do not specify, they can use whatever they want, even ways that are not in any of the specifications! What is standard to you may not be standard to them.


Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois



December 17, 2008appended

Q. I am struggling to understand which spec to use for passivation. Is there any clear direction or is it optional? Thanks for reading.

John Wilt
Engineer - Cambridge, Massachusetts


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December 19, 2008

A. The "right" spec is the one that your customer requires. ASTM A967 [link is to spec at TechStreet] is certainly more lax regarding passivation verification testing, which can be a good thing or a bad thing. AMS2700 [link is to spec at TechStreet] requires both solution and per-lot corrosion resistance testing.

Since you're considering an AMS spec, I assume you have aerospace customers. If not, I would stick with ASTM.

Terry Lycans
Aerospace - Dayton, Ohio, USA


December 19, 2008

A. One of the differences is in the definition of 'a lot' for testing purposes. ASTM A 967 uses the same definition as did the old Federal Specification, QQ-P-35.html, which allowed one to consider all production of similar material done in 24 hours to be a single lot. AMS 2700 considers different parts, or the same part made at different times, to be different lots (with the exception for parts with the legacy QQ-P-35 called out, when you can use the older definition.) You can guess the increase in the amount of testing involved.

There are other differences- ASTM A967 allows the use of any mix of nitric and water, so long as you show it works (Nitric 5 solution). The ASTM doesn't default to the nitric acid formulations, as AMS 2700 does. AMS 2700 has an iron concentration maximum, absent from ASTM A 967. AMS 2700 exempts 440C from testing. And there are other differences.

We design our own parts, and do our own passivation in house, and hence prefer the testing requirements of ASTM A967. If you're having it done for you, the testing is someone else's problem, so you might consider AMS 2700.

Lee Gearhart
metallurgist
East Aurora, New York


January 20, 2009

thumbsup2Terry/Lee, Thanks for your responses. They were helpful.

John Wilt
- Cambridge, Massachusetts



October 21, 2009appended

Q. Can you please tell me the differences between the passivation processes AMS2700 [link is to spec at TechStreet]C vs ASTM A967 [link is to spec at TechStreet] . I have a note requirement for the ASTM A967, Type 6 or 7 requirement on some parts and the parts were passivated to the AMS2700C, Method 1, Type 6 requirement.

Ted Nance
customer - San Diego, California


October 23, 2009

A. The two standards are essentially equivalent. Both contain a carryover of QQ-P-35C with the addition of the more recently developed citric acid based process. The AMS standard is used by the aerospace industry while the ASTM standard is used by generally everyone else.

QQ-P-35B contained six nitric acid bath Types. The C revision removed four of those and added two, leaving as options, Types II, VI, VII, and VIII. A967 renumbers those to 1 through 4 (there is no such thing as A967 Type 6 or 7) while 2700 restores the missing four for a total of eight Types.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois



AMS 2700 vs. AMS QQ-P35

March 22, 2013

Q. Explain the difference between passivation specs AMS 2700 and AMS QQ-P35

Dan Mason
- San Jose, California, USA


March 2013

A. Hi Dan. There is no AMS QQ-P35 anymore. It was cancelled in early 2003 in favor of AMS 2700.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey


November 23, 2013

Q. What are the differences in the passivation specs AMS 2700 and ASTM-A-967?

Bill Pinzon
- Greenlawn, New York, US

November 27, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

A. Hi Bill. As you see, we added your question to a thread which already answers it. Good luck.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

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