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Seals · ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections)

A2 (304) Stainless Steel Metric O-Rings (ISO 3601)

Mechanical properties, corrosion behaviour and the full dimensional range for this grade.

A2 Stainless Steel Metric O-Rings (ISO 3601) are supplied to ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70. Corrosion behaviour is good general corrosion resistance, the material is largely non-magnetic, and the usable service range is approx. -200 °C to +400 °C, subject to the property class and the joint. In practice this grade is the most common stainless group for indoor and general outdoor fasteners.

Grade
ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70
Corrosion resistance
Good general corrosion resistance
Magnetic response
Largely non-magnetic
Service temperature
approx. -200 °C to +400 °C, subject to the property class and the joint

Property values are typical for the grade. Certified mechanical test data is available on request for production orders.

A2 (304) Stainless Steel Metric O-Rings (ISO 3601) reference image

A2 Stainless Steel is not a material metric o-rings (iso 3601) are supplied in. Metric O-Rings (ISO 3601) are specified by inside diameter, and this combination does not describe a part that exists.

The materials that do apply are: NBR (Nitrile), FKM (Viton®-type), EPDM, Silicone (VMQ), PTFE.

See the Metric O-Rings (ISO 3601) product page for the specifications that do apply →

Custom manufacturing · Made to drawing

Need this seal in a grade that is not listed?

A2 Stainless Steel is one of the grades the catalog describes. A special seal is almost always a compound change rather than a size change — the same dimensions in a material that survives the medium.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

Custom seal manufacturingSend a drawing

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Dimensioned line drawing of 1.0 Metric O-Rings (ISO 3601) to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.
Typical inside-diameter range (mm)
1.0 – 20
Common compounds
NBR, FKM, EPDM, silicone
Notes
miniature and pneumatic
Sends the selected values to the quote form below.

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The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

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Specification
Business Information

Dimensions & Specifications (ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections))

Cross-section (mm)Typical inside-diameter range (mm)Common compoundsNotes
1.01.0 – 20NBR, FKM, EPDM, siliconeminiature and pneumatic
1.52.0 – 40NBR, FKM, EPDM, siliconesmall pneumatic and instrument
1.781.78 – 50NBR, FKM, EPDMnearest metric equivalent to the 1/16 in section
2.03.0 – 100NBR, FKM, EPDM, siliconegeneral hydraulic and pneumatic
2.55.0 – 150NBR, FKM, EPDMgeneral hydraulic
3.06.0 – 200NBR, FKM, EPDMgeneral hydraulic
3.510 – 250NBR, FKMhydraulic
4.012 – 300NBR, FKMhydraulic and larger flanges
5.020 – 400NBR, FKMlarge flanges and covers
5.3320 – 400NBR, FKMnearest metric equivalent to the 3/16 in section
6.025 – 500NBR, FKMlarge covers and housings

Applications & Industries

Where Metric O-Rings are used, and what decides the specification in each case. Stocked from 1.0 to 6.0 (inside diameter).

Industries that specify Metric O-Rings

  • Hydraulics Port, cover and piston seals.
  • Pneumatics Cylinder and valve seals.
  • Food and beverage EPDM and silicone compounds.
  • Chemical plant FKM for aggressive media.
  • Hydraulics & pneumatics Static and dynamic sealing in cylinders and valve bodies.
  • Process & food equipment Sealing at joints that are cleaned and inspected.

Typical applications

  • specifying inside diameter, cross-section and compound together
  • matching the compound to the fluid and the temperature
  • checking the groove dimensions give the right squeeze
  • using a back-up ring at high pressure
  • sealing a joint against fluid or air pressure
  • excluding dust and moisture from a housing

Service conditions to specify against

Sealed joints
Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life.

Where to use something else

  • Do not substitute an NBR ring for an FKM one because the dimensions match; the size fits and the compound fails, which looks like a leak with no cause.

Full application guide: where Metric O-Rings are used, how to specify them, and the cases they are wrong for

Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

What corrosion resistance do A2 Stainless Steel Metric O-Rings (ISO 3601) offer?

A2 Stainless Steel Metric O-Rings (ISO 3601) provide good general corrosion resistance with a service range of approx. -200 °C to +400 °C, subject to the property class and the joint.

Should I choose A2 Stainless Steel or A4 (316) for Metric O-Rings (ISO 3601)?

For Metric O-Rings (ISO 3601), A2 Stainless Steel suits general indoor and outdoor use; A4 (316) is preferred for marine, coastal and chemical environments. Choose by corrosion exposure first.

Can A2 Stainless Steel Metric O-Rings (ISO 3601) gall during installation?

Yes — stainless on stainless is prone to thread galling under load, especially at smaller sizes. Use an anti-galling lubricant or wax thread compound, and slow the tightening rate where possible.

Is A2 Stainless Steel food-grade?

A2 (304) is widely accepted for food contact in non-chloride environments; A4 (316) is preferred where chlorides are present.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.