---
title: "A2 (304) Stainless Steel Metric O-Rings (ISO 3601)"
description: "A2 (304) Stainless Steel Metric O-Rings (ISO 3601) (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70): good general corrosion resistance."
url: https://engineeringhardware.com/guide/material/a2-stainless-steel-metric-o-rings/
source: Engineering Hardware & Fasteners
---

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

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

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](https://engineeringhardware.com/wp-content/uploads/2026/09/Metric-O-Rings.webp)

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 →](https://engineeringhardware.com/fastener/metric-o-rings/)

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 manufacturing](https://engineeringhardware.com/custom/seals/)[Send a drawing](https://engineeringhardware.com/custom/seals/#rfq)

## Technical Drawing

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

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

| Cross-section (mm) | Typical inside-diameter range (mm) | Common compounds | Notes |
| --- | --- | --- | --- |
| 1.0 | 1.0 – 20 | NBR, FKM, EPDM, silicone | miniature and pneumatic |
| 1.5 | 2.0 – 40 | NBR, FKM, EPDM, silicone | small pneumatic and instrument |
| 1.78 | 1.78 – 50 | NBR, FKM, EPDM | nearest metric equivalent to the 1/16 in section |
| 2.0 | 3.0 – 100 | NBR, FKM, EPDM, silicone | general hydraulic and pneumatic |
| 2.5 | 5.0 – 150 | NBR, FKM, EPDM | general hydraulic |
| 3.0 | 6.0 – 200 | NBR, FKM, EPDM | general hydraulic |
| 3.5 | 10 – 250 | NBR, FKM | hydraulic |
| 4.0 | 12 – 300 | NBR, FKM | hydraulic and larger flanges |
| 5.0 | 20 – 400 | NBR, FKM | large flanges and covers |
| 5.33 | 20 – 400 | NBR, FKM | nearest metric equivalent to the 3/16 in section |
| 6.0 | 25 – 500 | NBR, FKM | large covers and housings |

Product catalog

## Related Metric O-Rings products

[![NG04 OEM Supported Manual Nail Shooting Gun Renovation Ceiling Fastener](https://img.engineeringhardware.com/NG04-OEM-Supported-Manual-Nail-Shooting-Gun-Renovation-Ceiling-Fastener.webp)](https://engineeringhardware.com/product/ng04-oem-supported-manual-nail-shooting-gun-renovation-ceiling-fastener/)

Common, Ring-Shank & Specialty Nails

### [NG04 OEM Supported Manual Nail Shooting Gun Renovation Ceiling Fastener](https://engineeringhardware.com/product/ng04-oem-supported-manual-nail-shooting-gun-renovation-ceiling-fastener/)

Carbon Steel · DIY, Industrial

**US$14.40 – 16.20**MOQ 2 pieces

[![6″ Diameter Gang Nail Anti Split Plate](https://img.engineeringhardware.com/6-Diameter-Gang-Nail-Anti-Split-Plate.webp)](https://engineeringhardware.com/product/6-diameter-gang-nail-anti-split-plate/)

Common, Ring-Shank & Specialty Nails

### [6″ Diameter Gang Nail Anti Split Plate](https://engineeringhardware.com/product/6-diameter-gang-nail-anti-split-plate/)

Galvanized Sheet Plate · 4",5",6",7",8",9",10" and so on

**US$0.24 – 1.92**MOQ 10,000 pieces

[![Wire Nails, Common Nails, Wood Nails, Iron Nails](https://img.engineeringhardware.com/Wire-Nails-Common-Nails-Wood-Nails-Iron-Nails.webp)](https://engineeringhardware.com/product/wire-nails-common-nails-wood-nails-iron-nails/)

Common, Ring-Shank & Specialty Nails

### [Wire Nails, Common Nails, Wood Nails, Iron Nails](https://engineeringhardware.com/product/wire-nails-common-nails-wood-nails-iron-nails/)

Common Nail, Common Nail · GB, GB

**US$600.00 – 780.00**MOQ 25 tons

[![High Quality Polished Common Round Wire Nail](https://img.engineeringhardware.com/High-Quality-Polished-Common-Round-Wire-Nail.webp)](https://engineeringhardware.com/product/high-quality-polished-common-round-wire-nail/)

Common, Ring-Shank & Specialty Nails

### [High Quality Polished Common Round Wire Nail](https://engineeringhardware.com/product/high-quality-polished-common-round-wire-nail/)

Common Nail · GB, ISO

**US$900.00 – 1,140**MOQ 2 tons

[![Shoe Nail Small Box, Woven Bag, Plasitc Box/SGS/Shoe Tacks Nail](https://img.engineeringhardware.com/Shoe-Nail-Small-Box-Woven-Bag-Plasitc-Box-SGS-Shoe-Tacks-Nail.webp)](https://engineeringhardware.com/product/shoe-nail-small-box-woven-bag-plasitc-box-sgs-shoe-tacks-nail/)

Common, Ring-Shank & Specialty Nails

### [Shoe Nail Small Box, Woven Bag, Plasitc Box/SGS/Shoe Tacks Nail](https://engineeringhardware.com/product/shoe-nail-small-box-woven-bag-plasitc-box-sgs-shoe-tacks-nail/)

ANSI, DIN, GB, ISO, JIS · Iron

**US$480.00 – 900.00**MOQ 5 tons

[![2″ Diamond Point Common Wire Nails](https://img.engineeringhardware.com/2-Diamond-Point-Common-Wire-Nails.webp)](https://engineeringhardware.com/product/2-diamond-point-common-wire-nails/)

Common, Ring-Shank & Specialty Nails

### [2″ Diamond Point Common Wire Nails](https://engineeringhardware.com/product/2-diamond-point-common-wire-nails/)

Nails · low carbon steel wire, Q195,SAE1008

**US$720.00 – 744.00**MOQ 1 ton

[View all Common, Ring-Shank & Specialty Nails →](https://engineeringhardware.com/fastener-products/nails-staples-tacks/common-ring-shank-specialty-nails/) [Full product catalog](https://engineeringhardware.com/products/)

## 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](https://engineeringhardware.com/applications/metric-o-rings/)

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](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 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.

## Related Pages

[View the full Metric O-Rings (ISO 3601) page](https://engineeringhardware.com/fastener/metric-o-rings/)

### More Metric O-Rings (ISO 3601) Guides