ASTM A967 vs ASTM A380: Passivation and Cleaning Standards Compared

Ask two different suppliers to "passivate per ASTM standards" and you may get two different results - because "ASTM standards" for stainless steel surface treatment actually means two separate documents that serve two separate functions. ASTM A380 and ASTM A967 are both published by ASTM Committee A01 and are both routinely cited on stainless steel drawings and purchase orders, but confusing one for the other is one of the most common - and most consequential - specification errors in stainless steel fabrication.

This guide explains exactly what each standard covers, how they relate to one another, and how to cite them so a passivation requirement is actually enforceable.

ASTM A967 vs ASTM A380

ASTM A380 is a Standard Practice - a broad procedural guide covering cleaning, descaling, pickling, and passivation recommendations for austenitic, ferritic, martensitic, and duplex stainless steels. ASTM A967 is a Standard Specification - a narrower, enforceable document that defines ten specific chemical passivation treatments (five nitric acid methods and five citric acid methods) plus the verification tests used to prove a surface was actually passivated. In practice: cite ASTM A380 to guide the cleaning and pickling process, and cite ASTM A967 to specify and verify the passivation result. The two standards are complementary, not competing, and both were revised in 2025 to share a single, harmonized technical definition of passivation.

The fundamental difference is one of document type: ASTM A380 is a Standard Practice, meaning it provides recommendations, procedures, and precautions for guidance, while ASTM A967 is a Standard Specification, meaning it defines mandatory, testable requirements - and this distinction in document type is precisely why the two are so often paired rather than substituted for one another.

What Is the Fundamental Difference Between ASTM A380 and ASTM A967

A "Standard Practice" in ASTM terminology is a set of instructions for performing an operation - think of it as a technical handbook. It tells a fabricator how cleaning, descaling, and pickling are typically done, and offers process guidance the supplier and purchaser can agree to apply. A "Standard Specification," by contrast, sets out defined values, limits, and pass/fail test criteria - it is the document a quality inspector uses to determine whether a part conforms.

This is why an industry rule of thumb has emerged among procurement and quality engineers: A380 describes how you clean and pickle; A967 defines and proves that you passivated correctly. Treating the two as interchangeable is the single most common specification error in this part of stainless steel fabrication.

ASTM A380, titled "Standard Practice for Cleaning, Descaling, Pickling, and Passivation of Stainless Steel Parts, Equipment, and Systems" as of its 2025 revision, covers the full pre-passivation workflow - cleaning, descaling, and pickling - along with general passivation guidance, applicable across austenitic, ferritic, martensitic, and duplex stainless steel grades.

Scope: recommendations and precautions for cleaning, descaling, pickling, and passivating new stainless steel parts, assemblies, equipment, and installed systems - and many of its techniques are also applicable to systems already in service.

Content: defines terminology (including three distinct definitions of "passivation" to avoid ambiguity), describes degreasing and solvent cleaning methods, mechanical descaling, chemical pickling parameters, and general passivation chemistries.

Appendix tables: Annex A1 (Table A1.1) details pickling processes by grade, concentration, and time/temperature; Annex A2 (Table A2.1) details passivation processes, though A380 explicitly defers to A967 for a more comprehensive list of passivation chemistries.

Grade coverage: applies primarily to austenitic, ferritic, martensitic, and duplex stainless steels, and notes its techniques may also be useful for other metals with appropriate consideration.

Because A380 is a practice rather than a specification, its passivation-related content is presented as guidance to be agreed upon between supplier and purchaser - which is exactly why quality and procurement professionals caution against citing A380 alone as a passivation acceptance specification on a drawing.

ASTM A967, titled "Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts," defines ten specific, parameterized chemical passivation treatments - five nitric acid methods and five citric acid methods - along with the mandatory verification tests used to demonstrate that a passivated surface actually meets the specification's acceptance criteria.

Treatment Family	Methods	General Characteristics
Nitric acid passivation	Nitric 1 through Nitric 5	Concentrations typically 20–50% by volume; parameters vary by grade and method per A967's process tables
Citric acid passivation	Citric 1 through Citric 5	Concentrations typically 4–10% by weight; milder worker-safety and environmental discharge profile than nitric methods

Per ASTM A967/A967M grade-specific process tables. Concentration, temperature, and immersion time vary by stainless grade - always confirm the specific method's parameters against the current-edition standard before specifying.

A967's defining feature - the one that makes it the enforceable "quality gate" of the two standards - is its suite of mandatory verification tests: water immersion, high humidity, salt spray, copper sulfate, potassium ferricyanide-nitric acid (ferroxyl), and a general free iron test. A specification callout such as "Passivate per ASTM A967, Nitric 2, verify by Practice D" gives a fabricator and inspector an exact, testable requirement; a callout that simply says "passivate" does not.

Both standards typically belong on a well-written drawing or purchase order, but they answer different questions: ASTM A380 governs how welded or heat-tinted parts should be cleaned and pickled beforehand, while ASTM A967 governs which passivation treatment to use and how its success will be verified - and a specification that cites only one of the two, or cites neither with enough specificity, leaves room for a supplier to use whatever process they consider adequate.

Which Standard Should Appear on a Purchase Order or Engineering Drawing

Callout	What It Actually Guarantees
"Passivate per ASTM standards"	Nothing enforceable - no standard is actually specified, and the supplier may apply any process they consider adequate
"Passivate per ASTM A380"	Weak - A380 is a practice, not a specification, and provides only general guidance rather than a defined, testable acceptance criterion
"Passivate per ASTM A967, Nitric 2"	Strong - a specific, defined chemical treatment with parameterized concentration, temperature, and time
"Pickle per ASTM A380; Passivate per ASTM A967, Citric 4; Verify by Practice D"	Fully enforceable - process guidance, a defined treatment, and a mandatory verification method are all specified

Format consistent with recommended drawing and RFQ callout practice for stainless steel fabrication procurement. A weak or ambiguous callout is a leading cause of receiving parts that are procedurally compliant but functionally under-passivated.

ASTM A967 contains the primary, mandatory suite of passivation verification tests, and ASTM A380 explicitly cross-references A967 for this content rather than duplicating a separate test regime - meaning a supplier working from either standard should ultimately be running the same underlying acceptance tests.

Water immersion: submerges parts in water and inspects for rust staining indicating residual free iron.

High humidity: exposes parts to a controlled high-humidity environment and inspects for corrosion.

Salt spray: exposes parts to a saltwater fog chamber to accelerate and reveal latent corrosion susceptibility.

Copper sulfate: applies an acidified copper sulfate solution; a coppery deposit indicates residual free iron (not valid on 400-series grades below 16% chromium).

Potassium ferricyanide-nitric acid (ferroxyl): applied primarily to welds; blue spots indicate free iron contamination that passivation failed to remove.

Free iron test: a general surface screening method for detectable free iron contamination.

A380's own text points the reader to A967 for the comprehensive list of acceptable passivation chemistries and their corresponding tests, rather than maintaining a fully independent test regime - which is a strong practical illustration of how the two standards are designed to work together rather than as competing alternatives.

The 2025 revisions of both standards harmonized their technical definition of passivation and expanded A380's title and scope to explicitly include pickling - changes that reduce, but do not eliminate, the potential for the two documents to be read as inconsistent with one another.

Unified passivation definition: both standards now reference the same Section 3.2.4 definition of passivation, removing a longstanding source of ambiguity between the two documents.

A380 title change: the standard's title was expanded to "Standard Practice for Cleaning, Descaling, Pickling, and Passivation of Stainless Steel Parts, Equipment, and Systems," explicitly naming pickling as a covered topic rather than leaving it implicit under "descaling."

Expanded terminology section: A380's Section 3 (Terminology) now provides three distinct definitions associated with the term "passivation" in common usage, helping purchasers state precisely which meaning they intend when a requirement is specified.

Because ASTM standards are revised on an ongoing cycle, the specific edition year should always be included in a drawing or purchase order callout - for example, "ASTM A967-23" rather than an unqualified reference to "ASTM A967" - to avoid disputes over which edition's requirements govern a given order.

Yes, for most welded stainless steel fabrications - because A380 addresses the pre-passivation cleaning and pickling steps that remove heat tint and scale, while A967 addresses the passivation treatment and verification that follows, and skipping either half of that sequence typically leaves a documented gap in the corrosion-protection record.

Do You Need Both Standards for a Single Fabrication Project

A welded fabrication with visible heat tint needs the pickling guidance in A380 to remove that heat tint and the underlying chromium-depleted layer before passivation can be effective - passivating over unremoved heat tint does not restore full corrosion resistance in the heat-affected zone. Once pickling is complete, A967 governs the passivation treatment itself and provides the acceptance tests that prove the result.

Our companion article, Pickling and Passivation of Stainless Steel Fabrications: A Complete Workflow, walks through this full six-stage sequence - degreasing, pickling, rinsing, passivating, rinsing and drying, and verification - in step-by-step detail.

An unqualified callout such as "passivate per ASTM standards" is effectively unenforceable, because it names no specific document, no treatment method, and no verification test - leaving the supplier free to apply any process they consider adequate, and leaving the purchaser with no contractual basis to reject a part that later shows corrosion in service.

No defined chemistry: without a cited method (for example, Nitric 2 or Citric 4), the supplier may select concentration, temperature, and immersion time at their own discretion.

No defined verification: without a cited test practice, there is no documented evidence the passivation treatment was even confirmed to work.

No basis for rejection: if a part corrodes in service, an ambiguous specification gives the purchaser little contractual leverage, since the supplier can reasonably claim they followed "a" recognized process.

No traceable Certificate of Conformance: a properly specified callout gives the supplier something specific to certify against; an ambiguous one does not.

The fix is straightforward and costs nothing beyond a few extra words on the drawing: name the exact standard, the exact method within that standard, and the exact verification practice required - the level of specificity discussed in Section 4 above.

Q: Is ASTM A380 a passivation specification?

A: Not on its own. ASTM A380 is a Standard Practice that provides general cleaning, descaling, pickling, and passivation guidance. Industry guidance from quality and procurement professionals recommends citing ASTM A967 - a Standard Specification - for the actual passivation requirement and its verification tests.

Q: Can ASTM A967 be used without ASTM A380?

A: Yes, for parts that do not require pickling - for example, machined components with no heat tint or scale. A967 alone can govern the passivation treatment and its verification. For welded fabrications with visible heat tint, A380's pickling guidance is typically needed first.

Q: What does 'Nitric 2' or 'Citric 4' mean in an ASTM A967 callout?

A: These refer to specific, parameterized passivation treatment methods defined within ASTM A967 - five nitric acid methods (Nitric 1–5) and five citric acid methods (Citric 1–5), each with its own concentration, temperature, and immersion time. Citing the specific method removes ambiguity about which treatment parameters apply.

Q: Did ASTM A380 and A967 used to define passivation differently?

A: Prior to their 2025 revisions, the two standards' passivation-related language had developed somewhat independently. The 2025 revisions harmonized both documents around a single definition, found in Section 3.2.4 of each standard, reducing the potential for conflicting interpretations.

Q: Which standard governs the verification tests used to prove passivation worked?

A: ASTM A967 contains the primary suite of verification tests - water immersion, high humidity, salt spray, copper sulfate, potassium ferricyanide-nitric acid, and a free iron test. ASTM A380 references this same test content rather than maintaining an independent set of acceptance criteria.