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Short answer: passivation of stainless steel is a chemical treatment applied to stainless steel parts, and ASTM A967/A967M is the specification that names the accepted treatments (nitric acid immersion, citric acid immersion and electrochemical treatment) and the tests used to check the result. ASTM A380/A380M is the separate practice for cleaning, descaling and passivating, and ASTM B912 covers passivation by electropolishing. Knowing which standard a purchase order or certificate cites is the fastest way to tell what was actually done to an instrument, vessel or length of tubing.
This guide is general product and standards information for laboratory, clinic and procurement staff. It is not a treatment procedure and not medical advice.
Definition and scope
ASTM A967/A967M-25 is titled “Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts”. ASTM lists it as an active standard, last updated 24 January 2025 (checked 30 October 2026). It is a specification: it describes treatments and the tests that show a part has been treated.
Passivation here means a chemical treatment of stainless steel parts. The A967 scope also covers recommendations and precautions for descaling and cleaning, and it says practices for the mechanical and chemical treatments of stainless steel surfaces are “discussed more thoroughly” in ASTM A380/A380M, which is why the two standards are so often quoted together.
How passivation is specified: ASTM A967 treatments and tests
The A967 abstract lists three treatment families: immersion treatment using nitric acid solutions, immersion treatment using citric acid solution, and electrochemical treatment. The scope describes its tests as qualitative tests intended to confirm the effectiveness of passivation, and lists them as practices A to G, which also include a damp cloth test and a boiling water immersion test.
The same abstract lists the tests the specification provides for checking a passivated surface:
- water immersion test
- high humidity test
- salt spray test
- copper sulfate test
- potassium ferricyanide-nitric acid test
- a free iron test, which the abstract says shall be used for detection of free iron on the surface
ASTM A380 vs A967: two different jobs
ASTM A380/A380M is titled “Standard Practice for Cleaning, Descaling, Pickling, and Passivation of Stainless Steel Parts, Equipment, and Systems”. Its scope covers recommendations and precautions for cleaning, descaling and passivating stainless steel parts, assemblies, equipment and installed systems, presented as procedures for guidance; which procedures apply may be specified by agreement between supplier and purchaser. ASTM lists A380/A380M-25 as the active edition (updated 15 January 2025); the 2017 edition shows as historical.
Read together: A380 is the practice that covers cleaning, descaling and passivation as a group, while A967 is the specification that names passivation treatments and the acceptance tests. Searches for “ASTM A967 passivation” and “ASTM A380 passivation” are therefore asking about two documents with different roles.
Electropolishing vs passivation: ASTM B912
Electropolishing and passivation are often compared, but the standards show they sit on different axes. ASTM B912 is titled “Standard Specification for Passivation of Stainless Steels Using Electropolishing” and covers passivation by electropolishing of stainless steel alloys in the 200, 300 and 400 series. ASTM’s store page lists B912-26 as the active edition (updated 16 June 2026); the earlier B912-02 (R2018) edition is the superseded one. ASTM’s A967 listing does not mention electropolishing, so A967 should not be quoted as covering it.
Where it matters for labs, clinics and supply decisions
Surface treatment shows up in documents for stainless instruments, vessels and sanitary tubing. For example, CASRAI’s single-use bioreactor vs stainless steel comparison mentions passivation records, and the stainless steel sanitary tubing size chart discusses electropolished surfaces. Related reading: cleaning validation and equipment qualification vs validation vs calibration.
Questions to put to a certificate or drawing
| Question | Why it follows from the standards |
|---|---|
| Which standard and which revision does the drawing or purchase order cite? | A967/A967M-25 and A380/A380M-25 are listed as active by ASTM; B912-26 is listed as the active edition, and the earlier B912-02 (R2018) is listed as historical. |
| Which treatment family was used: nitric acid, citric acid or electrochemical? | These are the three treatments in the A967 abstract. |
| Which acceptance test was run? | A967 lists water immersion, high humidity, salt spray, copper sulfate and potassium ferricyanide-nitric tests, plus a free iron test. |
| Was electropolishing part of the finish? | It is a separate route (B912), not something A967 describes. |
For sterilizer background, see what an autoclave is and sterilization validation.
Common misunderstandings
- Passivation, cleaning and descaling are not one step. A380 covers cleaning, descaling and passivating together as a practice, while A967 centres on passivation treatments and the tests that check them.
- Electropolishing is not covered by A967. It has its own specification, B912.
- “Passivated” is not self-certifying. A967 defines tests for checking a treated surface; a claim with no treatment family and no test named gives a reader nothing to check.
- “A967 vs A380” and “electropolishing vs passivation” are different comparisons. The first compares two documents; the second compares two surface routes.
FAQ
What is the difference between ASTM A967 and ASTM A380?
A967 is a specification for chemical passivation treatments and the tests that check them. A380 is a practice for cleaning, descaling and passivating stainless steel parts, equipment and systems, and A967 refers to it for further discussion of treatments.
What is ASTM A967 passivation?
It is passivation carried out under ASTM A967/A967M, using nitric acid immersion, citric acid immersion or electrochemical treatment, and checked with the tests the standard lists.
What is electropolishing vs passivation?
Electropolishing is its own finishing route, with ASTM B912 covering passivation by electropolishing of 200, 300 and 400 series stainless alloys. Chemical passivation under A967 is a different route.
Which tests does ASTM A967 list for checking passivation?
The abstract lists a water immersion test, high humidity test, salt spray test, copper sulfate test and potassium ferricyanide-nitric acid test, and says a free iron test shall be used for detection of free iron on the surface.
Sources
- ASTM International, A967/A967M-25, Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts, checked 30 October 2026.
- ASTM International, A380/A380M-25, Standard Practice for Cleaning, Descaling, Pickling, and Passivation of Stainless Steel Parts, Equipment, and Systems, checked 30 October 2026.
- ASTM International, B912-26, Standard Specification for Passivation of Stainless Steels Using Electropolishing, checked 30 October 2026.
