Help Centre
Have a technical question or issue about gaskets and sealing? Unsure about chemical resistance, temperature, or pressure? Take a look at our help centre.
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What rubber do I choose for my gasket?
Not all rubber is equal, especially when we consider the environment you are placing your gasket.
Here is a super quick overview of which polymer is for which situation – it’s fairly generalised and each rubber type has different grades. There are always many questions and giving us a call with your gasket environment will also get you to your answer quickly!
Nitrile – the most commonly used polymer for gaskets – has good temperature resistance and is very resistant to oil and fuel.
EPDM – potable water? EPDM is a great drinking water option with low taste and taint, it doesn’t leach into drinkable water sources.
Silicone – High temperatures, food grade? Silicone is probably what you need.
Non-Asbestos Fibre – High temperatures, fuel, and oil, steam – this is the modern version of using asbestos.
Viton – Trying to seal strong chemicals with a rubber seal? Viton might just do it.
Neoprene – a good value all-round rubber, with average temperatures, not requiring food grade or potable water, neoprene is used as a good all-rounder for less tricky environments.
Rubberised Cork – all the epic capabilities of cork (expansion, longevity) mixed with either neoprene or nitrile depending on how oily your environment is. Lots of grades of this material, are excellent for long-lasting industrial gaskets.
Looking to be more specific than this list? – Take an in-depth look at our gasket materials here
You don’t have to know everything about gaskets – just ask us! Use the contact form to send us a message.
Gasket Material Chemical Compatibility & Resistance
Choosing the correct gasket material for your application is critical, especially in an environment where you may be sealing against aggressive chemicals (e.g strong acids or alkalis). In this situation, you will want to know which chemicals are present; making sure that you are using a gasket with the right chemical resistance or compatibility.
The purpose of this article is to give some general information about the chemical resistance of gasket materials, particularly in rubbers.
This article covers: Some of the rubber gasket materials with the best chemical resistance. | How to make sure that pipe or flange gaskets are chemically resistant. | The best materials to seal against common chemicals | Why it’s best to work with a specialist or expert when specifying your gasket or material.
When designing a gasket or seal, chemical resistance is one of the most important steps to consider. For more information on compatibility with specific chemicals please see our chemical compatibility charts.
Rubber Gasket Chemical Compatibility
Nitrile (NBR) Gasket Chemical Resistance
Nitrile (or NBR) rubber is used with fuels and oils. It has very good resistance to these substances, and is able to seal when fluctuations of temperature are present. Nitrile is generally used in automotive and machine environments, or anywhere that fuel and oil are commonly used. Like other rubbers nitrile comes in different grades. A quality Nitrile specification can be fully submerged in oil and maintain good resistance, and will not swell in reaction to the oil but care must be taken with certain additives and biofuels. A common use of nitrile is as a binder to be mixed with aramid fibres (non-asbestos jointing): together they create a strong heat resistant gasket material that is also very durable in a fuel and oil environment. Where there is burning fuel there is often excessive heat in such environments non-asbestos jointing provides an excellent gasket material.
EPDM Gasket Chemical Resistance
EPDM has good resistance to nitrogen, potassium and sodium. Due to its low taint and taste, and excellent UV resistance, it is often used in water-based external environments. Any water pipe applications that has high volumes of sodium, or nitrogen, are commonly sealed using EPDM. If heat is an added factor a non-asbestos jointing with an EPDM rubber binder and aramid fibre blend gives an excellent seal against both the chemicals and the heat that the material will be subjected too.
Viton Gasket Chemical Resistance
Viton® is a branded synthetic rubber used in extreme chemical environments. It has excellent resistance to a wide range of chemicals including chlorinated hydrocarbons, fuels, and many acids. It is not suitable for ketones, such as organic acids and acetone, but has very good heat resistance up to 200ºC. Viton is very expensive, but should be used consistently where guarding against failure is absolutely critical, and a top quality product is required. One cost-effective solutions for sealing against aggressive chemicals is to add a PTFE envelope to the bore of a gasket to give extra chemical protection.
Pipe Gasket Chemical Resistance
A cost-effective way of sealing pipe gaskets from strong chemicals is to use a PTFE envelope; a liner that covers the area of the gasket that comes into contact with the contents of the pipe. PTFE is expensive, using a solid gasket is not usually recommended as the gasket can creep away from the pressure over time. Using a PTFE envelope both reduces the cost and doesnt compromise the sealing capability of a rubber or aramid fibre based gasket.
A PTFE envelope, in contrast, is a cheaper and effective way of sealing against aggressive chemicals whilst maintain the flexibility and temperature resistance of a quality pipe gasket. PTFE envelopes can be supplied to fit all standard pipe gaskets, or specifically milled to fit gaskets for non-standard flanges.
Ram Gaskets can mill specific dimensions if required. Modified PTFE gaskets, Blue, White and Fawn are popular chemically resistant gaskets.
Sealing Against Common Chemicals
As a general rule, the following materials will seal against these chemicals. If there is more than one chemical present in your environment, please contact us for expert help and support. Also, there may be a range of materials that would work in your application (each with different cost implications); it is therefore best to contact us to find out what options are available to you.
- Ammonia: EPDM, Neoprene
- Anti-freeze: Glycol based Nitrile, EPDM, Neoprene
- Chlorine: Viton® with PTFE envelope
- Ethanol: EPDM, Neoprene, Butyl
- Helium: all polymers will seal against helium
- Hydrogen Gas: Nitrile, EPDM, Neoprene
- Methanol: Viton®, Nitrile (grade A), Silicone rubber and Fluorosilicone.
- Nitrogen Gas: Most rubbers will seal against nitrogen gas (Nitrile, Natural rubber or EPDM would be the most commonly requested)
- Oxygen: Neoprene, Butyl and Viton will seal against oxygen, gaskets should be cleaned before installation. (Oxygen cleaned materials are requested to ensure there is no grease present. Certification can be requested for individually bagged and oxygen cleaned gaskets)
- Sulphuric Acid above 96%: PTFE and expanded PTFE, Viton FKM, AFLAS, and EPDM with a PTFE envelope
Rubber Chemical Resistance
The above recommendations are subject to certain qualifications. When designers and engineers specify a rubber there needs to be an awareness that not all rubbers are equal: even the same type or brand of rubber can be subject to variations that will affect its chemical resistance.
Rubber Grades
There are many different grades of synthetic rubber, and these rubbers come from many sources worldwide. Rubber is a compound of the original base Polymer such as Nitrile or EPDM and is blended with other rubbers, binder additives and fillers. It is important to have a significant proportion of base polymer to achieve the performance in the environment. It is critical to have a good supplier that understands the product and ensures that gaskets are consistently made with the correctly sourced material. The rubber content, and quality, of the gaskets needs to be both reliable and maintained over the course of your production. RAM has a clear supply chain and stock management system allowing for the best quality materials to be supplied to suit each requirement. .
Additives and Chemical Concentration
Chemicals are often blended, which makes the job of specifying the correct gasket material even more problematic. As already outlined, nitrile rubber is often used within sectors such as oil and gas, and the automotive industry. Nitrile usually has an excellent resistance to fuel and oil. However, when the percentages of additives changes in the fuel, such as an increase in naptha (a common fuel additive) nitrile goes from being an excellent sealant to simply a passable one.
For example, it has been widely publicised that Supermarket fuels containing high levels of additives can wreak havoc on seals over long-term use. If you are using a high quantity (greater than 5%) of a fuel additive over a long period of time, it is advisable to use viton: which has excellent resistance to both nitrile and naphtha.
Another example of this is bio fuel additives, such as ethanol in the U.K. When vehicles are left in storage for long periods of time, the ethanol will separate to the bottom of the tank where the localised high percentage can attack rubbers, fuel lines, and the metal of the fuel tank itself.
Chemical Compatibility: Cost Versus Performance
When specifying a material or gasket to cope with chemical resistance, weighing the cost of the materials against the long-term longevity and performance of the product is critical. Testing different materials is a sensible approach, yet in reality there is often not the time or budget to run tests on multiple different assemblies. We are able to advise, give you the benefits of our experience and provide test samples should they be required.
Our chemical compatibility charts can give you an idea of which materials to specify on your parts or drawing. Having said this, bear in mind that in certain cases higher quality grades of cheaper materials may well provide you with the sealing that you need, and at a reduced cost.
Our chemical charts have a range of A, B, C etc. to show how well they can be used to seal against certain chemicals. Some materials will swell in use, while this doesn’t necessarily lead to a failure it is often part of a compromise of functionality and cost.
Acetaldehyde to Calcium Hypochlorite
| Nat | Sbr | Neo | Nit | Epd | But | Hyp | Vit | Sil | Ptf | Naf | Grf | |
| Acetaldehyde | B | X | B | X | A | A | B | X | A | A | S | A |
| Acetic Acid 10% | B | B | A | B | B | B | B | B | A | A | A | A |
| Acetic Acid 100% | B | X | B | X | B | B | B | X | B | A | S | A |
| Acetone | B | B | B | X | A | A | B | X | B | A | B | A |
| Acetylene | A | A | B | A | A | A | A | A | B | A | S | A |
| Alum | A | A | A | A | A | A | A | A | A | A | A | A |
| Aluminium Chloride | A | A | A | A | B | A | A | A | B | A | S | A |
| Ammonia Gas Cold | A | A | A | A | A | A | A | X | A | B | S | A |
| Amyl Acetate | B | X | A | X | X | B | X | X | X | A | B | A |
| Aniline | X | X | X | X | X | A | B | A | X | A | X | A |
| Asphalt | X | X | B | B | X | X | X | A | X | A | S | A |
| Aviation Fuel | X | X | B | A | X | X | X | A | X | A | S | A |
| Benzene | X | X | X | B | B | X | X | A | X | B | S | A |
| Benzyl Chloride | X | X | X | X | X | X | B | A | X | – | S | A |
| Borax | A | A | A | A | A | A | A | A | B | A | A | A |
| Boric acid | A | A | A | A | A | A | A | A | A | – | A | A |
| Butane | X | X | B | A | X | X | A | A | S | A | S | A |
| Butyl Acetate | X | X | X | X | X | B | X | B | X | A | B | A |
| Butyl Alcohol | A | A | A | A | A | A | A | A | B | A | S | A |
| Calcium Hydroxide | A | A | A | A | B | A | A | B | A | A | A | A |
| Calcium Hypochlorite | A | X | B | B | A | A | A | A | B | A | S | B |
Alcium Sulphate to Ethylene Chloride
| Nat | Sbr | Neo | Nit | Epd | But | Hyp | Vit | Sil | Ptf | Naf | Grf | |
| Calcium Sulphate | A | A | A | A | A | A | A | A | – | A | A | A |
| Carbolic Acid | B | B | B | B | B | B | B | B | X | A | X | A |
| Carbon Dioxide | A | A | A | A | B | A | A | A | B | A | A | A |
| Carbon Disulphate | X | X | X | B | B | X | X | A | – | A | S | A |
| Carbon Tetrachioride | X | X | X | B | X | X | X | A | X | A | B | A |
| Chlorine (Dry) | X | X | B | B | X | B | X | B | X | A | S | B |
| Chlorine (Wet) | X | X | X | B | X | B | X | X | – | B | B | B |
| Chloroform | X | X | X | X | X | X | X | A | X | A | B | A |
| Chromic Acid | X | X | X | X | B | B | A | B | B | A | X | X |
| Citric Acid | A | A | A | B | A | A | A | A | A | A | A | A |
| Creasote | X | X | B | A | X | X | B | A | X | A | B | A |
| Cresol | X | X | X | X | X | B | X | A | X | A | B | A |
| Cyclohexanol | X | X | A | B | X | X | B | A | X | A | A | A |
| Cyclohexanone | X | X | X | X | B | B | X | X | X | A | X | A |
| Decalin | X | X | X | X | X | X | X | A | X | A | A | A |
| Di-Benzyl Ether | X | X | X | X | X | B | X | B | – | A | X | A |
| Diesel Oil | X | X | B | A | X | X | X | A | X | A | S | A |
| Dimethyl Formamide | X | X | X | A | B | B | X | X | B | A | X | A |
| Ethyl Acetate | B | B | X | B | B | A | X | X | B | A | S | A |
| Ethyl Alcohol | A | A | A | A | A | A | A | A | B | A | A | A |
| Ethyl Chloride | B | B | B | B | X | B | B | A | X | A | B | A |
| Ethylene Chloride | X | X | X | X | X | X | X | XA | X | A | X | A |
Ethylene Glycol to Malic Acid
| Nat | Sbr | Neo | Nit | Epd | But | Hyp | Vit | Sil | Ptf | Naf | Grf | |
| Ethylene Glycol | A | A | A | A | A | A | A | A | A | A | A | A |
| Ethyl Ether | X | X | X | B | X | B | X | X | X | A | S | A |
| Formaldehyde | A | A | B | A | B | A | A | A | B | A | S | A |
| Formamide | A | A | A | A | – | – | – | X | – | A | B | A |
| Formic Acid (10%) | A | A | A | B | B | A | A | X | B | A | A | A |
| Glycerine | A | A | A | A | A | A | A | A | A | A | A | A |
| Heating Oil | X | X | B | A | X | X | B | A | X | A | S | A |
| Heptane | X | X | B | A | X | X | A | A | X | A | A | A |
| Hydraulic Oil | X | X | A | A | X | X | A | A | S | A | S | A |
| Hydrochloric Cold 20% | A | B | A | B | A | A | A | A | B | A | B | A |
| Hydrochloric Cold 37% | A | B | A | B | B | B | A | A | B | A | X | A |
| Hydrofluoric Acid | X | X | B | X | B | B | A | A | X | A | X | A |
| Hydrogen | B | B | A | B | B | A | A | A | B | A | S | A |
| Hydrogen Peroxide 6% | B | B | B | B | B | B | B | A | A | A | A | A |
| Iso-Octane | X | X | A | X | X | X | A | X | X | A | A | A |
| Isopropyl Alcohol | A | A | A | A | A | A | A | A | A | A | A | A |
| Kerosene / Paraffin | X | X | B | A | X | X | B | A | X | A | A | A |
| Lactic Acid | B | B | B | B | B | B | A | A | A | A | A | A |
| Linseed Oil | X | X | B | A | B | A | A | A | A | A | A | A |
| Liquid Petroleum Gas | X | X | A | A | – | X | X | X | B | – | A | A |
| Lubricating Oil | X | X | B | A | X | X | B | A | X | A | S | A |
| Malic Acid | A | A | A | A | X | B | X | X | B | A | A | A |
Methane to Potassium Carbonate
| Nat | Sbr | Neo | Nit | Epd | But | Hyp | Vit | Sil | Ptf | Naf | Grf | |
| Methane | X | X | B | A | X | X | B | A | X | – | S | A |
| Methyl Alcohol | A | A | A | A | A | A | A | B | A | A | A | A |
| Methyl Chloride | X | X | X | X | B | B | X | B | X | A | B | A |
| Metylene Chloride | X | X | X | X | X | X | X | B | X | A | X | A |
| Methyl Ethyl Ketone | X | X | X | X | A | B | X | X | X | A | B | A |
| Motor Oil | X | X | A | A | X | X | X | A | B | A | S | A |
| Naptha | X | X | X | B | X | B | B | A | X | A | S | A |
| Natural Gas | B | B | A | A | B | B | A | A | A | A | A | A |
| Nitric Acid Dilute | X | X | B | X | B | A | A | X | B | A | S | X |
| Nitrobenzene | X | X | X | X | X | X | X | X | X | A | X | A |
| Nitrogen | A | A | A | A | A | A | A | A | A | A | A | A |
| Octane | X | X | A | A | X | X | A | A | X | A | S | A |
| Oxalic Acid | B | B | B | B | B | A | A | B | B | A | B | A |
| Oxygen – Cold (Care!) | B | B | A | B | A | A | A | A | A | A | S | B |
| Palmitic Acid | B | B | A | A | B | B | B | A | X | A | A | A |
| Paraffin / Kerosene | X | X | B | A | X | X | B | A | X | A | A | A |
| Pentane | X | X | B | A | X | X | B | A | X | A | S | A |
| Perchlorethylene | X | X | X | X | X | X | X | A | B | A | B | A |
| Petrol | X | X | B | A | X | X | X | A | B | A | B | A |
| Phenol | B | B | B | B | B | B | B | B | X | A | X | A |
| Phosphoric Acid | B | B | B | B | A | A | A | A | B | A | B | A |
| Potassium Carbonate | A | A | A | A | A | A | A | A | A | A | S | A |
Potassium Chlorate to Tannic Acid
| Nat | Sbr | Neo | Nit | Epd | But | Hyp | Vit | Sil | Ptf | Naf | Grf | |
| Potassium Chlorate | A | A | A | A | A | A | A | A | A | A | S | B |
| Potassium Dichromate | B | B | B | B | B | A | A | A | A | A | S | B |
| Potassium Hydroxide | B | B | B | B | B | A | A | B | B | A | B | A |
| Potassium Nitrate | A | A | A | A | A | A | A | A | A | A | A | B |
| Potassium Permanganate | B | B | B | B | A | A | A | A | – | A | A | B |
| Producer Gas | B | X | B | A | X | A | A | A | B | A | A | A |
| Propane | X | X | A | A | X | X | A | A | X | A | S | A |
| Pyridene | X | X | X | X | B | A | – | X | X | A | X | A |
| Sea Water | A | A | A | B | A | A | A | A | A | A | A | A |
| Silicone Oil | B | B | A | A | A | A | A | A | B | A | A | A |
| Skydrol | X | X | X | X | B | A | X | B | B | A | A | A |
| Sodium Carbonate | A | A | A | A | A | A | A | A | A | A | A | A |
| Sodium Chloride | A | A | A | A | A | A | A | A | A | A | A | A |
| Sodium Hydroxide | B | B | B | B | B | A | B | A | B | A | B | A |
| Sodium Sulphate | A | A | A | A | A | A | A | A | A | A | A | A |
| Steam Low Pressure | X | X | B | X | A | A | X | X | X | – | A | A |
| Steam High Pressure | X | X | X | X | X | X | X | X | X | – | B | A |
| Sulphuric Acid 30% | X | X | X | X | B | B | B | A | X | A | X | B |
| Sulphuric Acid 50% | X | X | X | X | X | B | B | B | X | A | X | B |
| Sulphuric Acid 96% | X | X | X | X | X | B | B | B | X | A | X | X |
| Suphurous Acid | A | B | B | A | A | A | A | A | X | A | B | A |
| Tannic Acid | A | B | B | B | B | B | B | A | B | A | A | A |
Tar to Xylene
| Nat | Sbr | Neo | Nit | Epd | But | Hyp | Vit | Sil | Ptf | Naf | Grf | |
| Tar | X | X | B | B | X | X | B | A | B | A | S | A |
| Tartaric Acid | A | A | A | A | B | A | A | A | A | A | A | A |
| Tetrachlorethane | X | X | X | X | X | X | X | A | – | A | B | A |
| Toluene | X | X | X | B | X | X | X | A | X | A | S | A |
| Trichlorethylene | X | X | X | X | X | X | X | B | X | A | B | A |
| Turpentine | X | X | X | B | X | X | X | A | X | A | A | A |
| Wines and Spirits | A | A | A | A | A | A | A | A | A | A | A | A |
| White Spirit | X | X | B | A | X | X | X | A | X | A | S | A |
| Xylene | X | X | X | B | X | X | X | A | X | A | S | A |