ASTM A967 & A380 Explained: Stainless Passivation Standards

ASTM A380 is a standard practice — process guidance for cleaning, descaling, and passivating stainless steel parts, equipment, and systems. ASTM A967 is a standard specification — it defines chemical passivation treatments and the acceptance tests used to confirm the result. Put simply: A380 tells you how to do the work (including removing scale and weld heat tint), and A967 tells you what the passivation treatment and the finished surface must satisfy.

ASTM A380 is the standard practice for cleaning, descaling, and passivation of stainless steel parts, equipment, and systems. Because it is a practice, it reads as guidance rather than a rigid pass/fail spec: it describes methods, sequences, and precautions for getting a stainless surface genuinely clean and free of contamination.

Its scope is broad. A380 addresses degreasing and removing shop soils, dealing with embedded iron and other surface contamination, and — importantly — descaling, which covers removing oxide scale and the weld heat tint (that blue/straw/brown discoloration) left by welding and heat treatment. That heat tint sits over a chromium-depleted zone, so A380-style descaling (often chemical pickling) is what takes the surface back to sound metal before passivation. A380 also discusses rinse-water quality, inspection, and ways to check cleanliness.

In other words, A380 is the document you lean on for the sequence of work: how to clean, how to descale welds, how to passivate, and how to avoid re-contaminating the part afterward. If your parts are welded or carry oxide scale, A380’s descaling guidance is the relevant half — see removing weld heat tint and cleaning stainless after welding.

ASTM A967 is the standard specification for chemical passivation treatments for stainless steel. Where A380 is open-ended guidance, A967 is written as a specification you can buy and inspect to: it defines passivation treatments and the acceptance tests used to judge whether a surface is adequately passivated.

A967 recognizes more than one chemistry. The two families you’ll see most are nitric acid passivation (the long-established approach) and citric acid passivation (a lower-hazard, widely adopted option). It organizes these into defined treatments so a drawing can call out a specific method rather than just “passivate.” For a deeper look at those options, see citric vs. nitric vs. pickling.

Crucially, A967 pairs the treatment with acceptance testing. Rather than assuming a part is passivated because it went through a bath, A967 lets you verify the result against defined criteria — which is what makes it the standard QC departments and auditors want cited. Note what A967 is not: it is not a descaling procedure. If a part has weld heat tint or oxide scale, that must be removed first (A380 territory); passivation does not remove scale or the chromium-depleted layer beneath it.

Here is the contrast at a glance — what each standard is, what it covers, and when to cite it.

The practical heart of A967 is acceptance testing — the evidence that a surface is actually passivated and free of free iron (the embedded or deposited iron that flash-rusts and interrupts the chromium-oxide passive film). Several test methods are recognized; which one applies depends on the part, the service, and the contract:

• Water immersion test — alternating immersion and drying cycles; free iron rusts, a passivated surface stays clean.
• High-humidity test — the part sits in a controlled humid environment; rust spots reveal remaining free iron.
• Salt spray — a more rigorous corrosion exposure for demanding qualification.
• Copper sulfate test — a fast, on-the-spot check: solution applied to the surface plates out a visible copper (pink) deposit wherever free iron is present. No deposit means a clean, passivated surface.

The copper sulfate test is the most common shop-floor acceptance check because it’s quick and needs no chamber — our Passivation Test Kit is exactly this copper-sulfate free-iron test. Note that some methods aren’t suitable for every grade or every finished part (for example, the copper sulfate test is generally not used on parts that will contact food), so match the test to your application and specification.

For most fabrication and QC work, a repeatable three-stage workflow satisfies both standards:

1. Clean & descale (A380). Degrease to remove oils and shop soils, then remove any oxide scale or weld heat tint. For welded parts, a brush-on pickling gel or paste — Wonder Gel or SS-3 Paste — dissolves heat tint and the chromium-depleted layer and restores the passive film in one step, no immersion tank or electricity required.
2. Passivate (A967). On clean, scale-free surfaces, passivate to remove free iron and let the chromium-oxide film re-form. SS-3 Liquid passivates by immersion or brush-on; Wonder Gel both pickles and passivates for welds and localized areas. Lighter touch-ups where you only need brightening — not descaling — are a job for B-P No.1 Brightner or B-P Metal Cleaner, not a passivation per A967.
3. Rinse, dry & verify. Rinse thoroughly with clean water, dry, handle with clean gloves, then run the acceptance test your spec calls for — commonly the copper-sulfate free-iron check with the Passivation Test Kit. Record the result for your documentation.

Bradford Derustit has manufactured these chemistries in the USA for over 50 years, and the SS-3 and Wonder Gel lines are formulated to meet both A380 and A967. For the broader picture of why passivation matters, see our complete passivation guide and why stainless steel rusts.

If you’re writing or reading a spec, the choice usually comes down to what the part needs:

• Welded or scaled parts — cite A380 for the cleaning and descaling you need, then A967 for the passivation treatment and acceptance. The two work together.
• Machined or already-clean parts — A967 is often enough on its own, since there’s no scale to remove — just free iron.
• Systems and installed equipment — A380’s practice guidance is especially useful, because it addresses cleaning assembled hardware, not just loose parts.

Whatever you cite, define the acceptance test so there’s no ambiguity about what “passed” means. For welds specifically, our guide on passivating stainless welds walks through the combined pickle-and-passivate approach.

Pickling and passivation chemicals are acids and must be handled by trained personnel with proper PPE (chemical goggles or face shield, resistant gloves and apron), ventilation, eyewash access, and correct rinse-water and waste handling. Always read the Safety Data Sheet before use.