GRN O-rings are technical sealing elements designed for industrial, maintenance, production and MRO applications. Their simple geometry makes them one of the most widely used sealing solutions, but reliable performance depends on correct selection of size, material, hardness and operating conditions.

TG Ersatzteile Polska Sp. z o.o. has developed the GRN range since 2007, supplying sealing products to professional customers in Poland and other European markets.

At simmering.pl, GRN O-rings are available in a wide range of dimensions and materials, supporting everything from individual repair requirements to recurring industrial orders and larger B2B quantities.

What Is an O-Ring and How Does It Work?

An O-ring is a circular sealing ring with a round cross-section.

When installed in a properly designed groove, it is compressed between mating surfaces. This elastic deformation creates the sealing force required to limit leakage.

O-rings are particularly well known as static seals, but properly selected designs can also be used in certain dynamic applications.

Typical applications include:

• hydraulic systems
• pneumatic systems
• pumps
• valves
• industrial machinery
• production equipment
• oil systems
• water installations
• automotive systems
• maintenance and repair

Their popularity results from the combination of simple design, compact dimensions and a very broad range of available sizes and materials.

How Are O-Ring Dimensions Specified?

A common O-ring size format is:

Inside Diameter x Cross-Section

For example:

20x3 mm

means an O-ring with:

20 mm nominal inside diameter
3 mm nominal cross-section

Both values are important.

A 20x3 mm O-ring is not the same product as a 20x2.5 mm O-ring, even though the inside diameter is identical.

The cross-section influences groove filling and compression, so even a small difference can affect sealing performance.

Why Is O-Ring Material So Important?

Dimensions alone are not enough to specify an O-ring correctly.

Two rings with identical dimensions may be manufactured from NBR, FKM, EPDM, Silicone/MVQ or another material, and each material behaves differently.

A more complete specification should therefore include:

size + material + hardness

For example:

20x3 mm - NBR - 70 ShA

In professional applications, operating medium, temperature, pressure and sealing conditions should also be considered.

GRN NBR O-Rings

NBR - Nitrile Butadiene Rubber - is one of the most widely used elastomers for O-ring production.

NBR offers good resistance to many mineral oils and lubricating greases together with useful mechanical properties for general technical applications.

GRN NBR O-rings may be used, after correct technical selection, in areas such as:

• hydraulics
• pneumatics
• industrial machinery
• pumps
• valves
• oil systems
• technical equipment
• maintenance applications

Exact chemical and temperature resistance depends on the specific NBR compound.

GRN NBR 70 ShA and 90 ShA O-Rings

Not all NBR O-rings have the same hardness.

Common variants include:

NBR 70 ShA
NBR 90 ShA

ShA refers to hardness measured on the Shore A scale.

An NBR 90 ShA O-ring is harder than an NBR 70 ShA O-ring, so the two can behave differently under compression and pressure.

They should therefore not be treated as automatic substitutes simply because the dimensions are identical.

GRN FKM / FPM O-Rings

FKM, also referred to as FPM in some European markets, is a fluoroelastomer used in more demanding sealing applications.

FKM O-rings can provide high temperature capability and good resistance to many oils, fuels and chemical media.

Typical application areas may include:

• industrial machinery
• automotive systems
• chemical installations
• fuel systems
• equipment operating at elevated temperatures

FKM should not automatically be considered a “better NBR”.

The correct material is the material that matches the operating medium and working conditions.

GRN EPDM O-Rings

EPDM has very different characteristics from NBR and FKM.

It can be suitable for many applications involving water, hot water, steam and compatible media.

Typical uses may include:

• water systems
• valves and fittings
• heating systems
• HVAC equipment
• technical installations

EPDM is generally not intended for mineral oil applications.

This is a clear example of why O-rings should never be selected by dimensions alone.

GRN Silicone / MVQ O-Rings

Silicone / MVQ is used where the flexibility and temperature-related properties of a selected silicone compound are advantageous.

Silicone O-rings can be suitable for technical and specialist applications.

However, material type and regulatory compliance are not the same thing.

A silicone O-ring is not automatically FDA-compliant or automatically approved for food-contact applications.

Where a specific approval is required, the documentation for the actual product or material compound must be verified.

PTFE O-Rings

PTFE behaves differently from conventional elastomers.

It offers high resistance to many chemicals and a low coefficient of friction, but it does not behave like a flexible NBR or FKM O-ring.

For this reason, PTFE O-rings should be treated as specialised sealing components requiring application-specific selection, not as universal replacements for elastomeric O-rings of the same nominal size.

Static and Dynamic O-Ring Applications

O-rings are widely used as static seals.

In a static application, the mating surfaces do not move relative to each other after assembly.

A typical example is a sealed housing or flange connection.

However, O-rings can also be used in certain dynamic applications where controlled motion occurs.

In such conditions, additional factors become particularly important:

• friction
• lubrication
• mating surface quality
• movement speed
• material
• groove design

An O-ring intended for a static application should not automatically be used dynamically.

Why Does O-Ring Hardness Matter?

Hardness affects how the elastomer deforms under load.

Two O-rings with the same dimensions but different hardness values may respond differently to compression, pressure and groove geometry.

For industrial applications, a specification such as:

NBR 70 ShA

is therefore an important part of the product definition.

Replacing a 70 ShA O-ring with a 90 ShA version should be based on application requirements, not simply product availability.

Common Causes of O-Ring Failure

An O-ring may fail even when its nominal dimensions appear correct.

Typical causes include:

• incorrect material
• wrong hardness
• incorrect size
• excessive compression
• installation damage
• twisting
• contaminated groove
• incompatible medium
• unsuitable temperature
• mechanical wear
• incorrect groove design

If an O-ring fails repeatedly, the entire sealing system should be evaluated, rather than simply installing the same ring again.

GRN O-Rings for Maintenance and MRO

Maintenance departments often need far more than one O-ring size.

A production plant may operate machines from many different manufacturers and from different generations.

As a result, maintenance teams may need:

• many inside diameters
• different cross-sections
• several materials
• different hardness grades
• larger quantities of frequently used sizes

The GRN O-ring range at simmering.pl is developed with these requirements in mind.

GRN O-Rings for Manufacturers

For serial production, repeatability of specification and supply becomes especially important.

A machine or equipment manufacturer may use the same O-ring for many years.

A useful production enquiry should therefore include:

size | material | hardness | medium | temperature | quantity

as well as estimated monthly or annual demand.

This provides a much clearer technical requirement than simply sending a size.

Wholesale GRN O-Rings

simmering.pl also serves customers requiring larger quantities of O-rings.

Depending on the size and variant, products may be available in packaging suitable for maintenance stock, technical warehouses and industrial consumption.

A typical enquiry may look like:

22x3 mm | NBR | 70 ShA | 1,000 pcs

For larger requirements, customers can submit multi-item dimension lists.

This is particularly useful for:

• manufacturers
• maintenance departments
• service companies
• distributors
• workshops
• MRO buyers

GRN - In Our Range Since 2007

TG Ersatzteile Polska Sp. z o.o. was established in 2002, and the GRN brand was introduced to our product range in 2007.

Since then, we have developed the supply of GRN sealing products for professional customers.

GRN products have been used by manufacturers in Germany as well as customers in France and other European countries.

Throughout our supply history, we have not recorded a quality complaint concerning the GRN sealing products supplied by us.

In 2026, this represents 19 years of real supply experience with GRN.

For a B2B customer, this is more meaningful than generic marketing terms such as “premium” or “highest quality”.

Where Are GRN O-Rings Manufactured?

GRN O-rings are manufactured in China according to the specification applicable to the individual product.

Modern elastomer seal production requires control over many parameters, from material formulation and moulding to dimensions and final finishing.

For a technical buyer, country of manufacture alone should not be the primary criterion for evaluating a sealing product.

More important factors include:

correct material, dimensions, hardness, product consistency and proven experience in actual use.

For this reason, rather than describing GRN as coming from “the most advanced factory in the world”, we prefer to base the brand's credibility on long-term supply history and real customer experience.

How to Order GRN O-Rings

The clearest way to identify an O-ring requirement is:

inside diameter x cross-section + material + hardness + quantity

For example:

O-Ring 22x3 NBR 70 ShA - 1,000 pcs

If the material is unknown, additional information may be required, including:

• operating medium
• temperature
• pressure
• type of movement
• equipment design

The more precise the technical data, the lower the risk of selecting an unsuitable seal.

simmering.pl - GRN O-Ring Supplier

simmering.pl is a specialist supplier of technical seals, O-rings, radial shaft seals and other industrial components.

We offer O-rings in a broad range of dimensions, materials and quantities.

We serve:

• industrial customers
• manufacturers
• maintenance departments
• MRO
• service companies
• workshops
• distributors
• B2B buyers
• individual customers

Our warehouse and store are located in Lublin, Poland, while orders are supplied to customers throughout Poland and to international markets.

FAQ - GRN O-Rings

What are GRN O-rings?

GRN O-rings are round-section sealing rings offered in different dimensions, materials and hardness grades for technical and industrial applications.

Since when has GRN been offered by simmering.pl?

TG Ersatzteile Polska Sp. z o.o. introduced GRN to its product range in 2007.

Where are GRN O-rings manufactured?

GRN O-rings are manufactured in China.

How is an O-ring size specified?

Typically as inside diameter x cross-section, for example 20x3 mm.

Which O-ring materials are available?

Depending on the product, the range includes NBR, FKM/FPM, EPDM, Silicone/MVQ and other materials.

What does 70 ShA mean?

It indicates elastomer hardness measured on the Shore A scale.

Can a 70 ShA O-ring be replaced by a 90 ShA O-ring?

Not automatically. Hardness is part of the seal specification and should match the application requirements.

Are O-rings only static seals?

No. They are widely used in static sealing, but correctly selected O-rings can also be used in certain dynamic applications.

Is every silicone O-ring FDA-compliant?

No. Food-contact or other regulatory compliance must be confirmed by documentation for the specific product or compound.

Does simmering.pl supply GRN O-rings in wholesale quantities?

Yes. We serve larger and multi-item requirements from manufacturers, maintenance departments, service companies and B2B customers.

GRN O-Rings - From Individual Repairs to Recurring Industrial Supply

An O-ring is a simple component, but reliable sealing depends on the correct combination of size, material, hardness and operating conditions.

Professional O-ring sourcing should therefore involve more than finding a ring with approximately the right diameter.

GRN has been part of our product range since 2007, giving us long-term experience supplying sealing products to professional customers in Poland and other European markets.

Today, simmering.pl develops the GRN O-ring range for everything from individual service requirements to maintenance, MRO, manufacturing, distribution and recurring B2B supply.