ASTM A380 is the standard practice that governs cleaning, descaling and passivation of stainless steel parts, equipment and systems. Where ASTM A967 specifies the passivation treatment itself, A380 covers everything around it: how to remove grease, scale, weld heat tint and embedded iron before treatment, which cleaning methods are acceptable, and how to verify the result. If a specification calls only for “passivation to A967” on a system that has just been welded, it is incomplete — A380 is the standard that tells you how to get the surface clean enough for A967 to work.
What is ASTM A380?
ASTM A380 / A380M is titled Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems. It is a practice rather than a specification, which matters: it describes accepted methods and gives guidance on selecting between them, rather than dictating a single acceptance number.
Its scope covers the whole surface-preparation sequence. That includes degreasing and removal of organic soils, removal of mill scale and weld scale, removal of weld heat tint, removal of embedded iron and other foreign particles, the chemical treatments used for each, the water quality used for rinsing, and the inspection methods used to confirm the surface is clean. It applies to parts on a bench and to installed piping systems alike, which is why it is the reference standard for field work on process and high-purity water systems.
The most common practical use of A380 in our work is as the governing document for pre-passivation cleaning on newly fabricated stainless piping, and as the reference for the inspection tests that demonstrate the cleaning worked.
ASTM A380 vs ASTM A967 — which standard applies?
This is the question we are asked most often, and getting it wrong is the reason a lot of passivation scopes under-deliver. The two standards are complementary, not alternatives.
| ASTM A380 | ASTM A967 | |
|---|---|---|
| Document type | Standard Practice | Standard Specification |
| Primary subject | Cleaning, descaling and passivation | Chemical passivation treatments |
| Covers degreasing | Yes | No |
| Covers scale and heat tint removal | Yes | No — requires it to be done first |
| Defines specific treatment methods | General guidance | Yes — ten methods, C1–C5 and N1–N5 |
| Defines acceptance tests | Yes — inspection practices | Yes — test methods and criteria |
| Base metal removal | Pickling does remove metal | None |
| Typical use | How to prepare and verify the surface | What treatment to specify and how to prove it |
The correct construction for a specification is usually both: clean and descale in accordance with ASTM A380, then passivate in accordance with ASTM A967 Method C1 (or whichever method the service requires), and verify to the acceptance criteria of both.
What is descaling, and when is it required?
Descaling is the removal of the heavy, adherent oxide scale produced by hot working, annealing, or welding. It is a more aggressive operation than either cleaning or passivation, and it is required whenever visible scale or heat tint is present.
The distinction that matters on a jobsite is between scale and tint. Mill scale is thick, dark and obvious. Weld heat tint is thin — typically 20 to 100 nanometres — and shows as straw, gold, blue or violet coloring adjacent to a weld. Both are chromium-depleted, both are removed under A380, and neither will be removed by passivation chemistry. A surface passivated over heat tint is a surface with corrosion initiation sites designed into it.
What cleaning methods does ASTM A380 cover?
A380 groups methods by what they are intended to remove. Selecting the wrong family is the usual cause of a failed inspection.
| Method family | Removes | Typical chemistry or means | Removes base metal? |
|---|---|---|---|
| Degreasing / alkaline cleaning | Oils, greases, cutting fluids, organic soils | Alkaline detergent, 2–4%, 140–160 °F, 30–45 min | No |
| Mechanical cleaning | Heavy scale, weld spatter, gross contamination | Abrasive blasting, grinding, brushing with stainless media only | Yes — uncontrolled |
| Acid pickling | Mill scale, weld scale, heavy heat tint | 10–25% HNO3 with 1–3% HF, ambient to 140 °F, 30–120 min | Yes — 5 to 50+ µm |
| Passivation | Free iron; restores chromium oxide film | 4–10% citric or 20–25% HNO3, 140–160 °F, 30–60 min | No |
| Electropolishing | Surface iron; smooths and enriches chromium | Electrolytic, per ASTM B912 | Yes — controlled, a few µm |
| Final rinse | Residual chemistry | Deionized or WFI-quality water to specified conductivity | No |
One rule cuts across all of them: never use carbon steel tooling, brushes or abrasive media on stainless. Iron transferred from a carbon-steel wire brush embeds in the surface and produces rust spotting within days. A380 is explicit that only stainless or non-metallic media may contact the surface.
What is the difference between pickling and passivation?
They are routinely written into specifications as though interchangeable. They are not.
| Pickling | Passivation | |
|---|---|---|
| Purpose | Remove scale and heat tint | Remove free iron, restore passive layer |
| Chemistry | 10–25% nitric with 1–3% hydrofluoric | 4–10% citric, or 20–25% nitric |
| Temperature | Ambient to 140 °F | 140–160 °F (citric) |
| Contact time | 30–120 minutes | 30–60 minutes |
| Base metal removed | 5 to 50+ micrometers | None |
| Effect on surface finish | Dulls and roughens the surface | No measurable change |
| Hazard profile | High — hydrofluoric acid | Low with citric; moderate with nitric |
| Governing standard | ASTM A380 | ASTM A967 |
Because pickling removes measurable base metal and roughens the surface, it is generally avoided on finished product-contact surfaces where a specified Ra must be maintained. On an ASME BPE system with an SF4 finish requirement, pickling a section of tube can put you out of specification on surface roughness even though the scale is gone.
Do I need to pickle before passivating?
Only if scale or heat tint is present. On a clean, machined or as-supplied mill-finish surface carrying nothing worse than handling soils and free iron, degreasing followed by passivation is sufficient and is the normal sequence.
Pickling becomes necessary when the surface carries weld scale, heavy heat tint, or oxide from heat treatment. The decision is straightforward: if you can see color or scale after degreasing, passivation alone will not remove it.
Where heat tint is light, mechanical removal with stainless media or an electrochemical weld-cleaning unit is often preferable to full pickling, because it is localized, avoids hydrofluoric acid handling, and does not affect the finish of the surrounding tube.
What inspection and acceptance tests does ASTM A380 define?
A380 sets out the practices used to demonstrate that cleaning worked. These are the tests that belong in a turnover package.
| Test | What it detects | Method and duration | Pass criterion |
|---|---|---|---|
| Water break test | Residual oil or organic film | Flood the surface with clean water | Continuous unbroken film held ≥30 seconds |
| Copper sulfate test | Free iron on the surface | 6% solution applied for 6 minutes | No copper-colored deposit |
| Ferroxyl test | Free iron, higher sensitivity | Potassium ferricyanide solution | No blue coloration within 30–60 seconds |
| High humidity test | Residual contamination | 100% relative humidity, 100 °F, 24 hours | No rust or staining |
| Water immersion test | Residual contamination | 100–170 °F, 24 hours | No rust or staining |
| Salt spray (ASTM B117) | Corrosion resistance | 5% NaCl at 95 °F, 24–72 hours | No corrosion within the specified period |
| Visual inspection | Scale, tint, spotting, weld defects | Direct or borescope, under adequate light | No visible scale, tint or foreign matter |
| Rinse water analysis | Residual chemistry | Conductivity and pH of final rinse | Typically pH 6.5–7.5 and <2 µS/cm |
Does ASTM A380 apply to weld heat tint?
Yes, and this is one of its most important provisions. A380 requires that heat tint and oxide scale be removed before passivation. Passivation chemistry — whether citric or nitric — will not remove heat tint, and applying it over tint produces a surface that looks treated and is not.
The color of the tint indicates roughly how hot the metal got and how thick the oxide is: pale straw around 400–500 °F at about 20 nanometres, gold to tan at 500–600 °F, blue and violet at 600–900 °F approaching 100 nanometres, and dark scale above 1,100 °F. Anything beyond the palest straw should be removed on a product-contact surface.
Prevention is cheaper than removal. Adequate inert gas purge on the weld interior — and holding purge until the weld zone cools below the tinting temperature — keeps tint from forming at all.
What documentation should an A380 scope produce?
A cleaning operation that cannot be evidenced is difficult to defend in an audit. A complete turnover package for A380 work should contain, at minimum:
- The written procedure actually executed, including chemistry, concentration, temperature, contact time and flow rate
- Batch or lot certification for every chemical used
- Calibration records for the instruments used to verify temperature, conductivity and pH
- Recorded process parameters for each circuit or section treated, not a single blanket entry
- Final rinse water quality results, with the acceptance limit stated
- Inspection results for each acceptance test performed, identified by location
- A drawing or line list identifying exactly which circuits were treated
- Deviation records and their disposition, where parameters fell outside the procedure
For pharmaceutical and biotech systems this package usually forms part of the installation qualification file, which is why the line list and the calibration records matter as much as the chemistry.
How does A380 relate to ASME BPE and the CFR?
ASME BPE governs the design and construction of bioprocessing equipment, including surface finish designations and the minimum surface chromium-to-iron ratio of 1.3 to 1. A380 and A967 are the practices by which that surface condition is achieved and verified. BPE tells you what the surface must be; A380 and A967 tell you how to get it there.
On the regulatory side, 21 CFR 211.67 requires equipment to be cleaned and maintained at appropriate intervals to prevent contamination that would alter product quality, and 21 CFR 211.63 requires equipment to be of appropriate design and suitably located to facilitate cleaning. A documented A380 cleaning with recorded acceptance testing is the practical evidence that those requirements have been met at installation.
For food contact surfaces, 3-A Sanitary Standards and EHEDG guidance impose comparable surface and cleanability expectations, and A380 remains the accepted practice for achieving them on stainless.
Need ASTM A380 cleaning and passivation on a real system?
Paul Industries cleans, descales, passivates and documents stainless steel process and high-purity water systems nationwide — new construction and systems already in GMP service. We work to written procedures, record the parameters as executed, and hand over the acceptance test results with the line list they belong to.
Standards referenced: ASTM A380 · ASTM A967 · 21 CFR 211 · ASME BPE · 3-A Sanitary Standards · ASME B31.3
What drives the cost of an ASTM A380 cleaning scope
A380 scopes are priced on exposure time, access and verification, and two quotations for the same system can differ by a multiple because the bidders assumed different answers to the questions below. None of these is negotiable after mobilization.
- Whether the work is done in place or on the bench. An installed system cannot be immersed, so chemistry is circulated, which brings pumps, hoses, temporary connections, containment and site waste handling.
- Soil condition at the start. Light shop oils and handling marks are a degrease. Heavy mill scale or weld scale means a pickling step, which removes base metal and adds rinse cycles.
- Heat tint extent, which is set by purge discipline during welding rather than by the cleaning contractor, and which decides whether chemical descaling or mechanical removal is required.
- Surface area and internal volume, because chemistry charge, rinse water volume and spent solution disposal scale with the wetted surface and the fill volume of the circuit.
- Rinse water quality. Where the specification requires low conductivity or low chloride rinse water, that water is produced or trucked, and the last rinse can dominate the utility cost.
- Verification scope. A water break test costs minutes. A ferroxyl test costs a little more. Laboratory surface analysis is a separate service with its own turnaround.
- Waste stream. Spent pickling acid is a regulated waste with a different disposal route and cost than a spent rinse, and the difference is location dependent.
- Access and isolation. Blinding, draining, tagging and reinstating a live system is often more hours than the cleaning itself.
- Schedule. Work inside a shutdown window carries crew and standby time that the same scope does not carry when it runs against an open schedule.
What to require in an A380 scope of work before anyone mobilizes
A380 is a practice, so it offers choices rather than one answer. A scope that leaves the choices open is a scope that will be settled in the field by whoever is holding the hose. Fix the following in writing first.
- The sequence, written step by step: degrease, descale or pickle, rinse, passivate, final rinse, dry, with the decision rule for whether the pickling step runs at all.
- Each chemistry named by constituent and concentration, with the temperature range and the contact time for every step.
- Rinse water quality given as numbers, specifically a conductivity limit and a chloride limit, plus the point in the sequence where each applies.
- The acceptance tests named individually with their pass criteria: a continuous water film for the stated interval on a water break test, no blue reaction for ferroxyl, and no copper deposit for copper sulfate where that method is permitted on the grade in question.
- Which tests apply to which surfaces, since copper sulfate is not appropriate on every alloy and a specification that applies it everywhere will produce arguments.
- A coupon plan: material and condition matched to the system, how many, where they are placed in the circuit, and whether they are retained after acceptance.
- Tooling segregation stated as a requirement, with stainless or non metallic tools only, and a written prohibition on carbon steel brushes, slings and grinding media touching the surface.
- Elastomer and instrument compatibility confirmed before chemistry is selected, listing which seals, diaphragms and sensors are removed or isolated for the duration.
- Containment, neutralization and disposal responsibility assigned by name, with the waste route identified for each chemistry used.
- Protection and handover after cleaning: how surfaces are kept clean and dry, what covers go on open ends, and how long the cleaned condition is warranted before reinstatement.
Frequently asked questions about ASTM A380
What is ASTM A380?
ASTM A380 is the Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems. It covers degreasing, removal of mill scale, weld scale and heat tint, removal of embedded iron, the chemical and mechanical methods used for each, rinse water quality, and the inspection tests used to verify the result.
What is the difference between ASTM A380 and ASTM A967?
A380 is a practice covering how to clean, descale and prepare a stainless surface and how to verify it. A967 is a specification defining the passivation treatments themselves, including the ten methods C1 to C5 and N1 to N5, and their acceptance criteria. Most complete specifications cite both: clean and descale to A380, then passivate to A967.
Does ASTM A380 remove weld heat tint?
Yes. A380 covers removal of heat tint and requires it to be removed before passivation. Passivation chemistry will not remove heat tint, so a surface passivated over tint retains a chromium-depleted layer and the corrosion initiation sites that come with it.
What is the difference between pickling and passivation?
Pickling uses 10 to 25 percent nitric acid with 1 to 3 percent hydrofluoric acid to remove scale and heat tint, and removes 5 to 50 or more micrometers of base metal while dulling the surface. Passivation uses 4 to 10 percent citric or 20 to 25 percent nitric acid to remove free iron and restore the chromium oxide layer, and removes no measurable base metal.
Do I have to pickle before passivating?
Only when scale or heat tint is present. If degreasing leaves a clean surface with no visible color or scale, passivation alone is sufficient. If color or scale remains after degreasing, passivation will not remove it and pickling or mechanical removal is required first.
What is a water break test and what is the pass criterion?
A water break test floods the surface with clean water to detect residual oil or organic film. The surface passes if the water forms a continuous, unbroken film that holds for at least 30 seconds. Beading or breaking of the film indicates remaining organic contamination.
What is the copper sulfate test?
The copper sulfate test detects free iron on a stainless surface. A 6 percent copper sulfate solution is applied and left for 6 minutes. Any copper-colored deposit indicates free iron remains and the surface has not been adequately cleaned or passivated.
Can I use a carbon steel wire brush on stainless steel?
No. Carbon steel tooling, brushes and abrasive media transfer iron into the stainless surface, which then rusts. ASTM A380 requires that only stainless steel or non-metallic media contact the surface. This is one of the most common causes of rust spotting on newly fabricated systems.
What rinse water quality does A380 require?
A380 requires a final rinse with water of a quality that will not recontaminate the surface, and the acceptance limit is set in the project specification. In pharmaceutical work the final rinse is typically deionized or WFI-quality water, with acceptance around pH 6.5 to 7.5 and conductivity below 2 microsiemens per centimeter.
Is ASTM A380 required by the FDA?
A380 is not named in the regulations. However 21 CFR 211.63 requires equipment of appropriate design to facilitate cleaning, and 21 CFR 211.67 requires cleaning and maintenance that prevents contamination altering product quality. A documented A380 cleaning with recorded acceptance testing is the practical evidence used to demonstrate compliance at installation.
Does A380 apply to installed piping systems or only to parts?
Both, and that breadth is what distinguishes it from ASTM A967. A380 is a standard practice covering cleaning, descaling and passivation of stainless steel parts, equipment and systems, so it addresses installed pipework and vessels as well as discrete components. It also covers the steps A967 does not, principally removal of heat tint and weld scale, which passivation chemistry alone will not clear. Thorough specifications cite both: A380 for surface preparation, A967 for the passivation treatment and its verification.
What documentation should an ASTM A380 cleaning produce?
The turnover package should include the executed procedure with chemistry, concentration, temperature, contact time and flow rate; chemical batch certifications; instrument calibration records; recorded parameters per circuit; final rinse water results; acceptance test results identified by location; a line list of circuits treated; and any deviation records with their disposition.
What is the scope of ASTM A380 exactly?
It is a standard practice covering cleaning, descaling and passivation of stainless steel parts, equipment and systems, describing methods and acceptance tests. It is a practice document, meaning it describes recognised methods rather than mandating one.
What is the ferroxyl test and when is it used?
It is a chemical test using potassium ferricyanide that produces a blue colour where free iron is present on a stainless surface. It is highly sensitive and is used for detecting iron contamination, and because the reagent itself contaminates the surface, tested areas are cleaned afterwards.
How is the water immersion test performed?
The cleaned part is immersed in or wetted with high-purity water for a defined period and then examined for rust staining. It is slower than the chemical tests but avoids applying reagents to a product-contact surface, which makes it useful on finished equipment.
What causes a water break on a stainless surface?
A film of oil, grease or organic residue, which prevents water from sheeting evenly and makes it bead instead. The test is a cleanliness check rather than a passivation check, and a surface that fails it is not ready for passivation.
What is pickling and when is it needed?
Pickling uses a strong acid, usually a nitric-hydrofluoric mixture, to remove oxide scale and heat tint along with a thin layer of the metal underneath. It is needed where heat tint or scale is present, because passivation chemistry will not remove them.
Can heat tint be removed mechanically instead of chemically?
Yes, by abrasive blasting, grinding or brushing with stainless-only media, followed by cleaning and passivation. The risk is embedding abrasive or carbon steel contamination and roughening the surface, so the method is chosen against the surface finish requirement.
Why must carbon steel tools never touch stainless?
They transfer free iron into the stainless surface, which then rusts and becomes a corrosion initiation site. Segregating stainless-only brushes, grinding wheels, clamps and work surfaces is a basic requirement, and cross-contamination from shared shop tooling is a frequent source of unexplained rust.
What rinse water quality does ASTM A380 call for?
Water of a quality that will not itself deposit contamination, with chloride content controlled because chlorides drive pitting. For high-purity systems the final rinse is typically done with water meeting the system's own specification.
Why are chlorides a problem in rinse water?
Chloride ions break down the passive film locally and initiate pitting and stress corrosion cracking, particularly at elevated temperature and where they can concentrate by evaporation. A final rinse with high-chloride water can undo the treatment that preceded it.
What is the difference between cleaning and degreasing under A380?
Degreasing removes oils and organic films so that subsequent steps can act on the metal, while cleaning is the broader removal of soils and contamination. The practice separates them because an acid applied over grease does nothing useful.
What should be avoided when handling cleaned stainless?
Bare hands, carbon steel contact, unfiltered shop air, and storage where airborne iron or chlorides can settle. Recontaminating a cleaned surface before passivation is the most common way a correctly executed procedure produces a failed test.
What should an ASTM A380 cleaning record contain?
The procedure and chemistry used, concentrations, temperatures and contact times, the rinse water quality and results, the acceptance tests performed with their results and locations, the personnel involved and the equipment identification. Without the parameters the result is unrepeatable.
How does A380 relate to A967 in practice?
A380 covers getting the surface clean and descaled, which is the prerequisite. A967 covers the passivation treatment itself and its acceptance criteria. Work that jumps straight to A967 on a contaminated surface produces an inconsistent result.
Where can I get the ASTM A380 PDF, and is passivation per ASTM A380 the same as A967?
The ASTM A380 PDF is sold by ASTM International at store.astm.org; it is copyrighted, so copies posted elsewhere are usually outdated editions. On the second question: the passivation ASTM A380 describes is part of a broader practice covering cleaning, descaling and passivation of stainless steel parts, equipment and systems, including pickling, mechanical cleaning and precautions for installed systems. ASTM A967 is the specification that defines the acceptance requirements for chemical passivation treatments and their test methods. Drawings often cite both: A380 for the practice, A967 for the acceptance criteria.
Article sources
Related: Pickling and Passivation of Stainless Steel · Passivation Certificate: What ASTM A967 and A380 Require It to Record