ASTM F86: Passivation Standards for Medical Devices

ASTM F86 is the passivation standard for medical devices and surgical implants. Its full title is “Standard Practice for Surface Preparation and Marking of Metallic Surgical Implants”, and the current revision is F86-21. It is the standard buyers mean when they ask about medical device passivation, and it is not the same document as ASTM A967, which is what most industrial passivation is specified to.

Paul Industries builds and qualifies the process systems medical device manufacturers run on – cleanrooms and controlled environments, high-purity water, clean steam, sanitary process piping and CIP/SIP – and passivates that equipment to ASTM A967 and A380. F86 governs the devices those facilities produce rather than the plant that produces them, and the two get specified against each other constantly, so this guide sets out what F86 requires and exactly how it differs from the standards that apply to your equipment.

What ASTM F86 covers, and the part of the title people skip

Read the title carefully: surface preparation AND MARKING. F86 is unusual among passivation standards because it addresses both the surface treatment and how the device is marked – laser marking, electrochemical etching and the like – and it does so because marking a finished implant disturbs the passive layer it just created. A standard that covered only passivation would leave the most common way of undoing it out of scope.

The treatments it specifies are chemical and electrochemical, used to remove objectionable surface contaminants and to restore or promote an inert, passive surface – a metal oxide film. Some of those treatments are passivation; others are cleaning steps that precede it.

Materials in scope – and why that matters more here than elsewhere

The titanium case is the one most often misunderstood. Passivating titanium is not about forming the oxide – titanium does that instantly in air and cannot be stopped from doing it. It is about removing iron particles embedded during machining, forming and handling, which corrode in service and compromise a surface that is otherwise excellent. The oxide is not the deliverable; cleanliness is.

Nitinol is different again. Because the alloy is roughly half nickel and nickel release is a biocompatibility concern, surface treatment is not only about corrosion resistance – it determines the composition of the outermost layer and therefore how much nickel is available at the surface. Treatment choice on Nitinol is a biological decision as much as a metallurgical one.

The F86 process sequence

Note what F86 does not do: it does not offer the numbered designation families that ASTM A967 provides. It specifies a nitric process window directly. That makes it simpler to cite and less flexible – there is no citric option written into it the way A967 offers C1 through C5.

ASTM F86 vs ASTM A967 vs ASTM A380 – which applies to what

These three get cited interchangeably and they are not interchangeable. This is the table worth keeping.

Two practical consequences. If you make implants, F86 is your document and citing A967 alone does not cover the marking requirement or the non-ferrous materials. If you build process systems, A967 and A380 are yours, and citing F86 imports an implant-focused nitric-only process into work where citric is usually the better choice. Specifying the wrong one of these is a surprisingly common error in supplier requirements.

Why medical device passivation is judged differently from process equipment

The metallurgy is the same. The consequences are not, and that changes what evidence is expected.

• Residence time. Process equipment contacts product for minutes or hours. An implant is in contact with tissue for years or decades, so slow corrosion mechanisms that never matter in a pipe become the governing concern.
• Biocompatibility. Device surfaces are assessed under the ISO 10993 family. Surface treatment affects what the body sees and what is released, so passivation is part of a biological evaluation rather than only a corrosion one.
• Ion release. Nickel, chromium and cobalt release are specific concerns for implants and have no equivalent in food or pharmaceutical piping.
• Geometry. Implants have threads, porous coatings, blind features and fine detail. Coverage and complete rinsing are far harder than in a tube, which is why ultrasonic cleaning is in the sequence.
• Batch traceability. Device regulation expects treatment records traceable to the finished device, not merely to the lot of raw material.

The single biggest practical difference: an implant cannot be re-treated after it is implanted, and it cannot be inspected in service. All of the assurance has to exist before it leaves the factory. A process pipe can be derouged, repassivated and re-inspected for the whole of its life.

Related guides

• Passivation standards: ASTM A967 and AMS 2700 – the industrial equivalents in full.
• ASTM A380 cleaning and descaling – the procedural document behind the cleaning stages.
• Citric vs nitric passivation – the A967 designation set and the verification methods.
• Electropolishing vs passivation – electropolishing appears in F86 as an alternative electrochemical treatment.

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Frequently asked questions

What is the passivation standard for medical devices?

ASTM F86, titled “Standard Practice for Surface Preparation and Marking of Metallic Surgical Implants”. The current revision is F86-21, replacing F86-13. It covers stainless steel, cobalt chrome, titanium and Nitinol used in surgical implants, and it addresses both the surface treatment and the marking of the device – unusual among passivation standards, because marking disturbs the passive layer that was just created.

What is the difference between ASTM F86 and ASTM A967?

F86 is the medical device and surgical implant standard; A967 is the general industrial standard for chemical passivation of stainless steel parts. F86 specifies a nitric process directly – 20 to 45% by volume at room temperature for at least 30 minutes – while A967 offers numbered nitric and citric designations, N1 to N5 and C1 to C5. F86 also covers titanium and Nitinol and includes marking; A967 does neither.

What are the ASTM F86 passivation parameters?

Cleaning first – organic solvent degreasing, hot alkaline soak and ultrasonic cleaning – then nitric acid at 20 to 45 percent by volume, at room temperature, for a minimum of 30 minutes, at a specific gravity of roughly 1.1197 to 1.285, followed by thorough rinsing and drying. The cleaning sequence is not optional: passivating over residual oil passivates the oil rather than the metal.

Does titanium need passivation?

Yes, but not for the reason most people assume. Titanium forms a titanium dioxide layer spontaneously in air and cannot be prevented from doing so, so the treatment is not about creating the oxide. It removes iron particles embedded during machining, forming and handling, which corrode in service and compromise an otherwise excellent surface. On titanium the deliverable is cleanliness, not oxide formation.

Why does Nitinol need special consideration?

Because Nitinol is roughly half nickel, and nickel release is a biocompatibility concern. Surface treatment determines the composition of the outermost layer and therefore how much nickel is available at the surface, so the choice of treatment is a biological decision as much as a metallurgical one. This has no equivalent in stainless process equipment, where nickel release is not an assessed endpoint.

Can I use citric acid passivation for medical devices?

Not under ASTM F86 as written – it specifies a nitric process. Citric passivation is covered by ASTM A967 for stainless steel parts and is widely used industrially. If a device specification cites F86, the nitric process is what has been called for, and substituting citric is a deviation requiring justification and, usually, customer or regulatory agreement.

Why does ASTM F86 cover marking as well as passivation?

Because marking a finished implant – by laser or electrochemical etch – disturbs the passive layer that passivation just created. A standard covering only the treatment would leave the most common way of undoing it out of scope. F86 therefore addresses the sequence and any re-treatment needed after marking, which is a control point that industrial passivation standards have no reason to include.

How does medical device passivation differ from process equipment passivation?

The metallurgy is identical; the consequences are not. An implant contacts tissue for years, so slow corrosion mechanisms that never matter in a pipe become governing. Device surfaces are assessed under ISO 10993 for biocompatibility, ion release is a specific endpoint, and geometry is far more complex. Most importantly, an implant cannot be re-treated or inspected once implanted – a process pipe can be derouged and repassivated for its whole life.