---
title: "A4 (316) Stainless Steel O-Ring Seal"
description: "A4 (316) Stainless Steel O-Ring Seal (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80): superior, including marine and chloride environments."
url: https://engineeringhardware.com/guide/material/a4-stainless-steel-cad-svg-159-oring/
source: Engineering Hardware & Fasteners
---

# A4 (316) Stainless Steel O-Ring Seal

Seals · ISO / DIN

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

A4 Stainless Steel O-Ring Seal are supplied to ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80. Corrosion behaviour is superior, including marine and chloride environments, 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 specified for marine, coastal and chemical applications.

- **Grade:** ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80
- **Corrosion resistance:** Superior, including marine and chloride environments
- **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.

![A4 (316) Stainless Steel O-Ring Seal reference image](https://engineeringhardware.com/wp-content/uploads/2026/06/O-Ring-Seal-—-ISO-DIN-Series-159-—-ISO-DIN.webp)

A4 Stainless Steel is not a material o-ring seal are supplied in. O-Ring Seal 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 O-Ring Seal product page for the specifications that do apply →](https://engineeringhardware.com/fastener/cad-svg-160-oring/)

Custom manufacturing · Made to drawing

## Need this seal in a grade that is not listed?

A4 Stainless Steel is one of the grades the catalog describes. Inside diameter, cross-section and compound are the three that matter, and the compound is chosen against the fluid and the temperature rather than the dimensions.

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 5 O-Ring Seal — ISO / DIN (Series 160). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Outer diameter d2 (mm):** 9
- **Wire dia (mm):** 2
- **Material:** NBR 70
- **Working temp range:** -30 to +110 C

## Dimensions & Specifications (ISO / DIN)

| Inner diameter d1 (mm) | Outer diameter d2 (mm) | Wire dia (mm) | Material | Working temp range | Reference standard |
| --- | --- | --- | --- | --- | --- |
| 5 | 9 | 2 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 8 | 12 | 2 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 10 | 16 | 3 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 15 | 21 | 3 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 20 | 26 | 3 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 25 | 33 | 4 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 30 | 38 | 4 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 40 | 50 | 5 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 50 | 60 | 5 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 60 | 72 | 6 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 80 | 92 | 6 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |
| 100 | 114 | 7 | NBR 70 | -30 to +110 C | ISO 3601 / GB/T 3452 |

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## Applications & Industries

O-Ring Seal are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from 5 to 100 (inside diameter).

### Industries that specify O-Ring Seal

- **Process & food equipment:** Sealing at joints that are cleaned and inspected.
- **Hydraulics & pneumatics:** Static and dynamic sealing in cylinders and valve bodies.

### Typical applications

- excluding dust and moisture from a housing
- sealing a joint against fluid or air pressure

### 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.

Need help matching O-Ring Seal to your application? Send the assembly, the load and the environment with your enquiry and we will specify the size, material and finish against them.

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

### Can A4 Stainless Steel O-Ring Seal — ISO / DIN (Series 160) 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 A4 Stainless Steel food-grade?

A4 (316) is the standard food-contact stainless grade in most jurisdictions, particularly where chloride exposure (brines, dairy CIP) is present.

### Can A4 Stainless Steel O-Ring Seal — ISO / DIN (Series 160) be used with aluminum?

Yes, but stainless drives mild galvanic corrosion of aluminum in wet service — isolate with a coating, sleeve or paint, or accept the trade-off if the joint is dry and indoor.

### What's the service temperature limit for A4 Stainless Steel?

The practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint.

### 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 O-Ring Seal — ISO / DIN (Series 160) page](https://engineeringhardware.com/fastener/cad-svg-160-oring/)

### More O-Ring Seal — ISO / DIN (Series 160) Guides