---
title: "A2 (304) Stainless Steel Elastomer-Sealing Nuts"
description: "A2 (304) Stainless Steel Elastomer-Sealing Nuts (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70): good general corrosion resistance."
url: https://engineeringhardware.com/guide/material/a2-stainless-steel-elastomer-sealing-nuts/
source: Engineering Hardware & Fasteners
---

# A2 (304) Stainless Steel Elastomer-Sealing Nuts

Nuts · Trade series (elastomer-sealing nuts)

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

A2 Stainless Steel Elastomer-Sealing Nuts 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 Elastomer-Sealing Nuts reference image](https://engineeringhardware.com/wp-content/uploads/2026/09/Elastomer-Sealing-Nuts-APM-Hexseal-Seelnuts.webp)

A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. Specified on elastomer-sealing nuts it determines the corrosion behaviour (good general corrosion resistance) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint); the dimensions are ours rather than a standard's, and are listed in full below.

## Why Choose A2 Stainless Steel for Elastomer-Sealing Nuts

The most common stainless group for indoor and general outdoor fasteners. For elastomer-sealing nuts, this matters when good general corrosion resistance is the primary requirement.

## Mechanical & Physical Properties

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

## Corrosion Behavior in Service

A2 (304) gives excellent atmospheric and most-water corrosion resistance and is the most common stainless for Elastomer-Sealing Nuts in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).

## Galvanic & Galling Considerations

Two important notes for stainless elastomer-sealing nuts: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.

## Using Stainless Fasteners in Aluminum

Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.

## Sizes of Elastomer-Sealing Nuts Available in A2 Stainless Steel

| Thread size | Pitch (mm) | Sealing-rib height (mm) | Thread class | Temperature range (°C) | Finish |
| --- | --- | --- | --- | --- | --- |
| M3 | 0.5 | 0.2 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M4 | 0.7 | 0.3 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M5 | 0.8 | 0.4 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M6 | 1.0 | 0.5 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M8 | 1.25 | 0.6 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M10 | 1.5 | 0.6 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M12 | 1.75 | 0.8 | 6H | -75~+204 | zinc-chromate plated low-carbon steel |
| M14 | 2.0 |  | 6H | -75~+204 | zinc-chromate plated low-carbon steel |

Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in A2 Stainless Steel. The catalogue's default material column has been omitted here so it cannot be read as contradicting that.

Custom manufacturing · Made to drawing

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

A2 Stainless Steel is one of the grades the catalog describes. Thread size is the obvious variable and rarely the interesting one — height for clearance, across-flats for the tool already in the cell, and the locking feature for the vibration actually present. Made by cold heading or tapping.

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

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

## Technical Drawing

Dimensioned line drawing of M3 Elastomer-Sealing Nuts to Trade series (elastomer-sealing nuts). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Pitch (mm):** 0.5
- **Sealing-rib height (mm):** 0.2
- **Thread class:** 6H
- **Seal material:** silicone elastomer
- **Temperature range (°C):** -75~+204
- **Finish:** zinc-chromate plated low-carbon steel

## Dimensions & Specifications (Trade series (elastomer-sealing nuts))

| Thread size | Pitch (mm) | Sealing-rib height (mm) | Thread class | Seal material | Temperature range (°C) | Finish |
| --- | --- | --- | --- | --- | --- | --- |
| M3 | 0.5 | 0.2 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M4 | 0.7 | 0.3 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M5 | 0.8 | 0.4 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M6 | 1.0 | 0.5 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M8 | 1.25 | 0.6 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M10 | 1.5 | 0.6 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M12 | 1.75 | 0.8 | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |
| M14 | 2.0 |  | 6H | silicone elastomer | -75~+204 | zinc-chromate plated low-carbon steel |

Product catalog

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## Materials & Grades

Select a material class to see the grades we supply it in. Each designation is listed with its ISO/EN, AISI/SAE, JIS and GB equivalents.

Stainless Steel38 Carbon Steel66 Alloy Steel41 Bearing Steel5 Spring Steel25 Aluminum and Aluminum Alloys21 Brass17 Bronze11 Copper8 Titanium and Titanium Alloys18 Nickel and Nickel Alloys22 Iron-Nickel and High-Temperature Alloys10 Tool Steel and Specialty Hardened Steel9 Structural and Construction Steel9

### Stainless Steel

#### Austenitic Stainless Steel

- A1 AISI 303 · SAE 303 · SUS303 · EN 1.4305 · X8CrNiS18-9
- A2 AISI 304 · SAE 304 · SUS304 · EN 1.4301 · X5CrNi18-10 · 06Cr19Ni10
- 304L AISI 304L · SUS304L · EN 1.4307 · X2CrNi18-9 · 022Cr19Ni10
- 302 AISI 302 · SUS302 · EN 1.4310
- 305 AISI 305 · SUS305 · EN 1.4303
- A4 AISI 316 · SAE 316 · SUS316 · EN 1.4401 · X5CrNiMo17-12-2 · 06Cr17Ni12Mo2
- 316L AISI 316L · SUS316L · EN 1.4404 · X2CrNiMo17-12-2 · 022Cr17Ni12Mo2
- 321 AISI 321 · SUS321 · EN 1.4541 · X6CrNiTi18-10
- 310 / 310S AISI 310 · AISI 310S · SUS310S · EN 1.4845
- 302HQ AISI 302HQ
- A3
- A5
- 347 AISI 347 · SUS347 · EN 1.4550 · X6CrNiNb18-10
- 309 / 309S AISI 309 · AISI 309S · SUS309S

#### Martensitic Stainless Steel

- AISI 410 SUS410 · EN 1.4006 · X12Cr13 · 12Cr13
- AISI 420 SUS420J1 · SUS420J2 · EN 1.4021 · EN 1.4028 · 20Cr13 · 30Cr13
- AISI 431 SUS431 · EN 1.4057 · X17CrNi16-2
- C1
- C3
- C4
- AISI 440A
- AISI 440B
- AISI 440C SUS440C · EN 1.4125

#### Ferritic Stainless Steel

- AISI 430 SUS430 · EN 1.4016 · X6Cr17 · 10Cr17
- F1
- AISI 434
- AISI 444

#### Precipitation-Hardening Stainless Steel

- 17-4 PH AISI 630 · UNS S17400 · SUS630 · EN 1.4542 · X5CrNiCuNb16-4
- 15-5 PH UNS S15500
- 17-7 PH UNS S17700

#### Duplex and Super Duplex Stainless Steel

- Duplex 2205 UNS S31803 · UNS S32205 · EN 1.4462
- Super Duplex 2507 UNS S32750 · EN 1.4410
- D2
- D4
- D6
- D8
- Lean Duplex 2101 UNS S32101
- Super Duplex S32760 UNS S32760 · EN 1.4501

### Carbon Steel

#### Low-Carbon Steel

- SAE 1006
- SAE 1008
- SAE 1010
- SAE 1018
- SAE 1020
- Q195
- Q235
- SAE 1012
- SAE 1015
- Q215
- ML08
- ML08Al
- ML10
- ML15
- ML20
- SWRCH6A
- SWRCH8A
- SWRCH10A
- SWRCH12A
- SWRCH15A
- SWRCH18A

#### Medium-Carbon Steel

- SAE 1035
- SAE 1045
- S45C
- C45
- SAE 1030
- SAE 1040
- SAE 1050
- 30
- 35
- 40
- 45
- 50
- S35C
- S40C
- S50C
- C35
- C40

#### High-Carbon Steel

- SAE 1060
- SAE 1070
- 65Mn
- SAE 1065
- SAE 1075
- SAE 1080
- SAE 1085
- SAE 1090
- SAE 1095
- 60
- 65
- 70
- 75
- 80
- 85

#### Cold-Heading Steel

- SWRCH22A
- 10B21
- SWRCH22K
- SWRCH25K
- SWRCH30K
- SWRCH35K
- SWRCH40K
- ML20Mn
- ML25
- ML30
- ML35
- ML40
- 15B25

### Alloy Steel

#### Chromium Steel

- 40Cr
- 45Cr
- AISI 5140
- SAE 5140
- AISI 5120
- SAE 5120
- SCr420
- SCr440

#### Chromium-Molybdenum Steel

- 35CrMo
- 42CrMo
- AISI 4140
- SCM435
- SCM440
- 42CrMo4
- 30CrMo
- AISI 4130
- SAE 4130
- SAE 4140
- AISI 4142
- AISI 4145
- SCM415
- SCM420
- SCM445
- EN 1.7220
- EN 1.7225
- 25CrMo4
- 34CrMo4

#### Nickel-Chromium-Molybdenum Steel

- AISI 4340
- SAE 4340
- 40CrNiMo
- SNCM439
- EN 1.6511
- 36CrNiMo4

#### Boron Alloy Steel

- 10B22
- 10B21
- 15B21
- 15B25
- 20MnTiB
- 20Mn2B
- 35VB
- 40MnB

### Bearing Steel

#### Bearing Steel

- GCr15
- AISI 52100 SAE 52100 · UNS G52986
- SUJ2
- 100Cr6 EN 1.3505
- GCr15SiMn

### Spring Steel

#### Carbon Spring Steel

- SAE 1065
- SAE 1070
- SAE 1075
- SAE 1080
- SAE 1095
- 65
- 70
- 75
- 80
- 65Mn

#### Silicon-Manganese Spring Steel

- 60Si2Mn
- 60Si2MnA
- SUP6
- SUP7

#### Chromium-Vanadium Spring Steel

- 50CrVA
- SAE 6150
- AISI 6150
- SUP10

#### Stainless Spring Steel

- AISI 301
- SUS301
- EN 1.4310
- AISI 302
- AISI 304
- AISI 316
- 17-7 PH

### Aluminum and Aluminum Alloys

#### Commercially Pure Aluminum

- 1050
- 1060
- 1070
- 1100

#### 2xxx Series Aluminum

- 2024
- 2011
- 2014
- 2017

#### 5xxx Series Aluminum

- 5052
- 5083
- 5754

#### 6xxx Series Aluminum

- 6061
- 6061-T6
- 6063
- 6082
- 6082-T6

#### 7xxx Series Aluminum

- 7075
- 7075-T6
- 7005
- 7050
- 7075-T73

### Brass

#### Free-Cutting Brass

- C36000
- H62
- HPb59-1
- C3601
- C3602
- C3604
- CuZn36Pb3
- CuZn39Pb3
- EN CW614N
- EN CW617N
- H65

#### Lead-Free Brass

- C69300
- C27450
- CW510L
- CW511L

#### Naval Brass

- C46400
- CuZn39Sn1

### Bronze

#### Silicon Bronze

- C65500
- C65100
- C65600

#### Phosphor Bronze

- C51000
- C52100
- CuSn6
- CuSn8

#### Aluminum Bronze

- C95400
- C95500
- C63000
- CuAl10Ni5Fe4

### Copper

#### Copper

- C11000
- T2
- C10100
- C10200
- C12200
- T1
- TU1
- TU2

### Titanium and Titanium Alloys

#### Commercially Pure Titanium

- Grade 2
- Grade 1
- Grade 3
- Grade 4
- TA1
- TA2
- TA3

#### Alpha-Beta Titanium Alloys

- Grade 5
- Ti-6Al-4V
- TC4
- UNS R56400

#### Low-Interstitial Grade

- Grade 23
- Ti-6Al-4V ELI
- UNS R56407

#### Other Titanium Fastener Alloys

- Ti-6Al-6V-2Sn
- Ti-6Al-2Sn-4Zr-2Mo
- Beta-C titanium
- Ti-10V-2Fe-3Al

### Nickel and Nickel Alloys

#### Commercially Pure Nickel

- Nickel 200
- UNS N02200
- Nickel 201
- UNS N02201

#### Inconel Alloys

- Inconel 625 UNS N06625
- Inconel 718 UNS N07718
- Inconel 600 UNS N06600
- Inconel 601 UNS N06601
- Inconel 686 UNS N06686
- Inconel X-750 UNS N07750

#### Monel Alloys

- Monel 400 UNS N04400
- Monel K-500 UNS N05500

#### Hastelloy Alloys

- Hastelloy C-276 UNS N10276
- Hastelloy C-22 UNS N06022
- Hastelloy B-2 UNS N10665
- Hastelloy B-3 UNS N10675
- Hastelloy X UNS N06002

#### Other Nickel Alloys

- Alloy 20 UNS N08020
- Alloy 625
- Alloy 718
- Alloy 825 UNS N08825
- Alloy 925 UNS N09925

### Iron-Nickel and High-Temperature Alloys

#### A286

- A-286
- UNS S66286
- EN 1.4980

#### Invar

- Invar 36
- Alloy 36
- UNS K93600
- FeNi36

#### Alloy 42

- Alloy 42
- UNS K94100
- FeNi42

### Tool Steel and Specialty Hardened Steel

#### Tool Steel and Specialty Hardened Steel

- AISI D2
- AISI H13
- SKD11
- Cr12MoV
- AISI O1
- AISI A2
- AISI S7
- SKD61
- 9CrSi

### Structural and Construction Steel

#### Structural and Construction Steel

- ASTM A36
- Q235B
- Q355B
- S355JR
- Q235C
- Q355C
- S235JR
- S275JR
- S355J2

## Applications & Industries

The sectors that buy Elastomer-Sealing Nuts, and the duty each one buys them for. Stocked from M3 to M14.

### Industries that specify Elastomer-Sealing Nuts

- **Control cabinets:** Silicone ribs seal mounting points without a separate loose gasket.
- **Outdoor equipment:** Plated steel supports the nut while the elastomer handles the interface.
- **Process instruments:** Metric class 6H threads mate with panel hardware selected for the seal.
- **Weatherproof enclosures:** Sealing nuts close a threaded panel joint against water and dust.
- **Automotive & transport:** Vibration-prone joints where the locking type is specified on the drawing.
- **Maintenance & MRO:** Replacements matched to the existing bolt class, thread and finish.

### Typical applications

- matching the rib height and compression to the sheet
- checking the -75 to +204 °C service range
- keeping the mating screw and panel surface aligned
- sealing a threaded pass-through in a panel
- locking an adjustment so it cannot drift
- joints re-torqued at a service interval

### Service conditions to specify against

- **Marine and coastal:** Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- **High load:** Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- **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.
- **Match the class:** A nut below the bolt property class strips before the bolt reaches its own limit — pair class 8 nuts with 8.8 bolts, class 10 with 10.9.

### Where to use something else

- Do not rely on the nut as a pressure-vessel seal without checking compression, panel flatness and the actual sealing path.

[Full application guide: where Elastomer-Sealing Nuts are used, how to specify them, and the cases they are wrong for](https://engineeringhardware.com/applications/elastomer-sealing-nuts/)

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

### Are A2 Stainless Steel Elastomer-Sealing Nuts magnetic?

A2 Stainless Steel Elastomer-Sealing Nuts are largely non-magnetic.

### What corrosion resistance do A2 Stainless Steel Elastomer-Sealing Nuts offer?

A2 Stainless Steel Elastomer-Sealing Nuts 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 Elastomer-Sealing Nuts?

For Elastomer-Sealing Nuts, 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 Elastomer-Sealing Nuts 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.

### 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 Elastomer-Sealing Nuts page](https://engineeringhardware.com/fastener/elastomer-sealing-nuts/)

### More Elastomer-Sealing Nuts Guides