Nuts · Trade series (rubber blind nuts)

A2 (304) Stainless Steel EPDM Rubber Well Nuts

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

A2 Stainless Steel EPDM Rubber Well 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 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. When epdm rubber well nuts are specified in this grade, the dimensions remain per Trade series (rubber blind nuts); the material determines corrosion behavior (good general corrosion resistance) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint). Both are covered below with the size table.

Why Choose A2 Stainless Steel for EPDM Rubber Well Nuts

The most common stainless group for indoor and general outdoor fasteners. For epdm rubber well 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

Galvanic & Galling Considerations

Two important notes for stainless epdm rubber well 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.

Comparable Grades

For EPDM Rubber Well Nuts, the alternative stainless grade is A4 (316). A2 (304) covers general indoor and outdoor service. A4 (316) adds molybdenum, which is what buys the chloride resistance for marine and de-icing-salt exposure. Where strength matters more than corrosion, plated alloy steel in class 8.8 or 10.9 is the swap to make.

Using Stainless Fasteners in Aluminum

Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.

Sizes of EPDM Rubber Well Nuts Available in A2 Stainless Steel

Thread size	Representative hole diameter (mm)	Representative grip range (mm)	Temperature range (u00b0C)	Representative tightening torque (Nu00b7m)	Body / insert
M3	8.0	0.4~4.0	-30~+80	0.5	EPDM rubber / stainless threaded insert
M4	8.0	0.4~4.0	-30~+80	0.4	EPDM rubber / stainless threaded insert
M5	9.7	0.4~4.9	-30~+80	0.6	EPDM rubber / stainless threaded insert
M6	12.8	0.4~4.0 or 0.8~4.7	-30~+80	1.0	EPDM rubber / stainless threaded insert
M8	16.0	0.4~4.0	-30~+80	1.5	EPDM rubber / stainless threaded insert

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.

Sends the selected values to the quote form below.

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Specification

Item / category Standard Size(s) Material / finish Quantity

Business Information

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Notes

Dimensions & Specifications (Trade series (rubber blind nuts))

Thread size	Representative hole diameter (mm)	Representative grip range (mm)	Temperature range (u00b0C)	Representative tightening torque (Nu00b7m)	Body / insert
M3	8.0	0.4~4.0	-30~+80	0.5	EPDM rubber / stainless threaded insert
M4	8.0	0.4~4.0	-30~+80	0.4	EPDM rubber / stainless threaded insert
M5	9.7	0.4~4.9	-30~+80	0.6	EPDM rubber / stainless threaded insert
M6	12.8	0.4~4.0 or 0.8~4.7	-30~+80	1.0	EPDM rubber / stainless threaded insert
M8	16.0	0.4~4.0	-30~+80	1.5	EPDM rubber / stainless threaded insert

Applications & Industries

Where EPDM Rubber Well Nuts are used, and what decides the specification in each case. Stocked from M3 to M8.

Industries that specify EPDM Rubber Well Nuts

Vehicle body panels Rubber well nuts isolate and seal trim fasteners through thin skins.
Motorcycle service Blind rubber inserts provide a thread where the rear face is inaccessible.
Outdoor enclosures EPDM accommodates panel movement and keeps a small hole sealed.
Equipment covers Stainless inserts resist corrosion while the rubber body clamps the panel.
Steel fabrication Bolted structural and frame connections.
Automotive & transport Vibration-prone joints where the locking type is specified on the drawing.

Typical applications

adding a blind threaded point to a thin panel
matching hole diameter and grip range to the EPDM body
tightening only to the representative torque for the size
using the rubber body for isolation and sealing
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 over-tighten a well nut; excess compression can pull the insert through the panel or damage the seal.

Need help matching EPDM Rubber Well Nuts 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.

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.
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.
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.
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 A2 Stainless Steel replace plated alloy steel structurally?

Only at the standard strength classes — A2-70 / A4-80 are roughly equivalent to class 7 steel; A4-100 reaches class 8.8. For class 10.9 or 12.9 strength, plated alloy steel is required.

Are A2 Stainless Steel EPDM Rubber Well Nuts magnetic?

A2 Stainless Steel EPDM Rubber Well Nuts are largely non-magnetic.

What corrosion resistance do A2 Stainless Steel EPDM Rubber Well Nuts offer?

A2 Stainless Steel EPDM Rubber Well 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 EPDM Rubber Well Nuts?

For EPDM Rubber Well 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.

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.