Stainless steel in medicine and pharma

For contact with preparations, disinfectants and steam, austenitic 316L is used; for furniture, trays and non-critical parts, 304. Tool grades, which are strengthened by quenching, are a separate group of steels and do not relate to sheet and pipe products.

Industry requirements

The requirements for the material in medicine and pharma follow from two conditions: contact with a preparation or a biological environment, and regular treatment.

• Corrosion resistance. The metal must not react with preparations, disinfectants and cleaning solutions and must not release ions into the product.
• Surface cleanliness. A smooth surface without pores and scores does not retain residues and is easier to wash.
• Absence of stagnant zones. Dead ends, crevices and rough seams become places where contamination accumulates.
• Resistance to repeated treatment. Steam, autoclaving and chemical disinfection must not destroy the surface.
• Traceability. Documents are needed for the batch, showing the grade, the heat and the test results.
• Repairability. After a repair or rewelding of a seam, the component must again pass treatment and confirmation.

A practical rule follows from this: in medicine and pharma not only the grade matters but also how the seams, edges and internal cavities are made.

Grades

Grade	Where it is used	Features
AISI 304	Furniture, trays, trolleys, housings, non-critical parts	Not for aggressive disinfectants and chlorides
AISI 316L	Reactors, sinks, pipelines, contact with preparations	The main grade of the industry, resistance to chlorides and welding
AISI 316L electropolished	Internal surfaces, components after sterilisation	Minimal roughness, easier washing
Martensitic tool grades	Cutting and working tools	Strengthened by heat treatment, outside sheet products
AISI 430	Decorative panels out of contact with the environment	Not for damp and working areas

316L beats 304 for two reasons: molybdenum increases resistance to chlorides, and low carbon preserves the resistance of the weld seam. In pharma and medicine almost all equipment is welded, so the second reason is often more important than the first.

Austenitic 304 and 316L are not strengthened by quenching — only by work hardening during cold deformation. If a cutting tool is needed, martensitic grades are taken, which are quenched and tempered. That is exactly why the question "is stainless steel medical steel" is incorrect: the same grade may suit a reactor and not suit a scalpel.

Electropolishing

Electropolishing is an anodic treatment in an electrolyte. A thin layer of metal is removed from the surface, and the micro-peaks dissolve faster than the valleys, so the roughness falls.

What electropolishing gives:

• it smooths the micro-relief and removes burrs after machining;
• it enriches the surface layer with chromium, which improves the passive film;
• it removes inclusions and tool particles left after cutting and grinding;
• it makes washing and sterilisation easier and reduces product sticking;
• it makes the surface visually uniform, which simplifies inspection.

There are limitations too. Electropolishing does not replace pickling of deep scale after welding: first the seam is cleaned and pickled, then polished. It does not save from stagnant zones — if there is a dead end in the construction, a smooth surface will not help. After treatment a thorough rinse is needed so that no electrolyte remains in the cavities.

Electropolishing is applied not to the whole item but to those surfaces that contact the product. Outer panels and frames are usually left ground, because the cost of treatment does not justify the task.

Validation

Validation is confirmation that the treatment and cleaning process is reproducible and gives the specified result. It is not a one-off procedure but a set of records and checks.

What is recorded:

• the parameters of mechanical, chemical and electrolytic treatment;
• the results of roughness inspection at control areas;
• the results of tests for free iron and corrosion resistance;
• the washing and sterilisation scheme for the component;
• the list of places that cannot be dismantled and treated, and the justification why they are acceptable;
• the documents for the batch of metal.

After a repair, replacement of gaskets or rewelding of a seam, validation is repeated for the affected area. This is cheaper than dealing with a rejected batch of a preparation.

On the exchange the subject of the trade remains steel products: sheet, pipe, round bar and profile. Surface treatment, assembly of the apparatus and validation are performed by the equipment manufacturer, while the exchange only matches orders and records the trade. That is why it is advantageous to fix the grade and the surface condition in the order before matching, so that both parties have the same understanding of the subject of delivery.

Frequently asked questions

What is the difference between stainless steel and medical steel

The difference is not in the metal but in the requirements. Medical steel is stainless steel of a specific grade and surface treatment, approved for work in medicine and pharma. Ordinary stainless steel without such preparation is not approved for contact with preparations.

Is stainless steel medical steel

Not any. For medicine 316L is suitable and, in non-critical components, 304, while decorative and economy grades are not.

Which grade of stainless steel is used in medicine

The main grade is 316L: molybdenum gives resistance to disinfectants and chlorides, low carbon preserves the properties of the weld seam.

Why is 316L taken in pharma and not 304

Because of chlorides and welding. Disinfectants, saline solutions and preparations contain chlorides, and seams of 304 lose resistance in the heat-affected zone.

Why is electropolishing needed

It reduces roughness, enriches the surface with chromium and makes washing and sterilisation easier. It does not remove deep scale — pickling is needed first.

Can stainless steel be sterilised repeatedly

Yes, austenitic grades withstand repeated steam and chemical disinfection. The resistance depends on the grade and the surface condition.

What does surface validation confirm

The reproducibility of treatment and cleaning: the process parameters, the results of roughness inspection, tests for free iron and the documents for the batch of metal.

Is 304 suitable for medical furniture

Yes, for furniture, trays and housings out of contact with preparations. For working surfaces and internal cavities 316L is taken.

What to look at next

• AISI 316 — catalogue positions in the main grade of the industry.
• Food-grade stainless steel — rolled steel with surfaces for sanitary requirements.
• Food-grade stainless steel: grades and requirements — surfaces, seams and choice of grade.
• Passivation and pickling of stainless steel — how seams are treated before polishing.

Place an order

Choose the grade, surface and size in the catalogue of stainless steel products and place an order. Settlement and delivery take place between the parties, and the exchange records the trade and does not hold money for the goods.