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What Is a Gasket? Everything You Need to Know

By Scott Chambers on Jul 14, 2021 12:39:19 PM


Gaskets are everywhere. They’re in your car, at work, even in the air! A gasket is a common term used to describe any seal or grommet that holds two things together. You can make gaskets from rubber, plastic, metal, and other materials. The material choice depends on why you need to use a gasket.

But as you'll learn, there's more to gaskets than a seal preventing a leak. Before you blow a gasket trying to work out the difference between each one, let us do the dirty work for you and tell you everything you need to know about gaskets!

Definition of a Gasket

A gasket, also known as an O-ring or washer, seals the gap between two surfaces. In most cases, these items are made of rubber and are available in a variety of sizes and shapes depending on their purpose.

The most common type of gasket is the flat gasket. It has a cross-section that is circular in shape. The diameter of cylindrical gaskets ranges from 1/4 inch to 3 inches. Typically, the diameter of cylindrical gaskets is round. The tubular gasket appears as a long tube with a different diameter at each end.

It's important to point out that gaskets come in many different variations, as we'll see later on. In this article, we're going to move into more detail about the aspects of each of them. For the moment, let's have a look at the difference between a gasket and a seal.

How Are Gaskets Tested?

As part of the process of evaluation, gaskets undergo tests such as hot compression tests. This test determines the heat that the gasket can withstand without causing damage or failure in the gasket material.

It is then necessary to check for any leaks in the sealant, as well as look for any other problems such as pinholes or cracks with the sealant. As the final stage in the manufacturing process, technicians will conduct an examination of the product, checking it for all aspects before it leaves the facility.

Gasket or Seal?

Considering the fact that the word "seal" can both be used as a noun and a verb, a great many people confuse gaskets with seals, using both terms interchangeably. They both serve a very similar purpose, but there is one major difference.

In both cases, the items form a barrier between two objects to keep them from leaking. Yet the seal seeks to protect at least two moving parts (whether only one of the parts moves or both). These are commonly composed of flat and round washers, like the ones found in faucets.

There are two static seals that make up a gasket. These seals allow two static, non-moving parts to be locked together.

Because of this, they are often molded to fit a specific static application. Or, they might be malleable enough to fit into a given position and keep it there as long as they don't move against each other.

Properties of a Gasket

The gasket material should have good flexibility, low density, and high tensile strength. It should also have a resistance to chemicals and internal pressure, and durability. It must also have excellent adhesion properties with itself and anything it touches.

The ideal gasket will not only seal but also protect against corrosion. Further abrasion, vibration, impact, and temperature extremes need consideration.

That said, the most important feature of any gasket application is strength. It must have enough strength to withstand pressure without deforming under normal conditions. This is so it can serve its primary function of creating a tight seal.

What Are Some Use Cases for Gaskets?

Gaskets occur in many industrial applications. These include Food Processing, Petrochemical, Plumbing, Machinery, and Gas. The easiest way to summarize these is to think, "if it needs sealing and it doesn't move, chances are it's using a gasket."

Examples around the home include gaskets in water faucets, around windows. Appliances, such as refrigerators, have gaskets to keep cold air inside. Examples in the workplace might include gaskets in machinery, pipes, valves, and pumps.

Most people tend to think of head gaskets as stainless steel gaskets or metal gaskets used in cars. But as you can see, there is a whole range of gaskets.

Most often go disguised under a different name, like washers or o-rings. And, all these serve vital functions across a range of applications.

Types of Gaskets and Materials

There are many types of gaskets used in all kinds of settings. Each material is preferential depending on the most important properties required.

Gaskets come in various materials, including metal, plastic, silicone, and glass fiber reinforced polymers. But they all must fit snug against their mating surface, so there's no air leakage around them.

With this information, let's take a look at each type of gasket. Further, we'll look at their properties and how they apply in the everyday setting:

Rubber Gasket

The synthetic rubber gasket is one of the oldest forms of sealing technology. Charles Goodyear first developed rubber gaskets around 1844 for his invention of vulcanized rubber. They're made from natural or synthetic materials.

We go into greater detail about these below, as each is a little different. You can find rubber gaskets in a wide variety of applications, including:


The most common application of rubber gaskets is automotive use, where they're often found on doors and trunk lids to seal out moisture and other contaminants. Also, many vehicles have seals between their engine block and cylinder head which need an effective seal against water intrusion.

Rubber gasket manufacturers are looking for ways to improve the performance of their products by developing new formulations that provide better sealing characteristics at a lower cost than previous generations of materials, helping bring the cost of automotive parts down as a result.


Industrial uses include sealing equipment such as pumps, valves, conveyors, etc., where there's constant exposure to harsh chemicals and abrasive particles. These types of environments also create high heat loads, so these components must remain sealed tight.


Medical devices like catheters, tubing, IV bags, etc., all need to maintain a good seal to prevent contamination and infection. HVAC/R - HVAC systems rely a lot on airtight seals to keep the indoor environment clean and dry.

Food & Beverage

Gaskets are often used in food processing plants to ensure proper sanitation and safety. Food processors use gaskets to protect raw meat and poultry from cross-contamination with other foods during preparation. The same goes for beverage bottlers who use gaskets to help prevent leaks when filling bottles with carbonated beverages.

Silicone Gasket

Dr. William H. Dow Corning Company invented the silicone gasket in 1953. This product is often known as "silicone" because it contains silicon atoms within the molecule structure.

Silicones are durable and resistant to chemicals such as acids, alkalis, oils, solvents, water, heat, radiation, and ozone. This makes them an ideal choice for food processing applications.

Silicone rubber can exist a lot in medical devices since its introduction into clinical practice. Silicone rubbers have several desirable properties that make them useful in many industrial processes. These include high-temperature resistance, low compression set and good electrical insulating characteristics. They also possess excellent chemical inertness, biocompatibility, and an ability to be easily bonded or vulcanized with other materials.

EPDM Gasket

This is another form of elastomer, which stands for ethylene propylene diene monomers. EPDM is similar to silicone except contains additional ingredients like fillers, plasticizers, stabilizers, antioxidants, flame retardants, etc. These additives make up about 10% of the total weight of the polymer.

EPDM rubber has a high resistance against heat and chemicals, as well as good flexibility. It can be used in many automotive parts, industrial products, medical devices, toys, footwear, construction, and electronics.

Neoprene Gasket

Neoprene gaskets comprise a thermoplastic elastomer based upon polychloroprene. Neoprenes are widely used in medical devices due to their ability to maintain shape while being stretched over long periods. Because neoprenes do not stretch back out when released, they are often used in products where there is continuous motion.

In addition, these materials are highly elastic and flexible, so they can easily conform to irregular surfaces. The most common method for manufacturing neoprene gaskets involves using an extruder that heats and melts the polymer into its final form. The molten material then passes through a die orifice that shapes it into the desired product.

Other Gasket Styles and Materials

Here, we've mostly discussed rubber and silicone gaskets, but some gasket materials and designs cross over, or you may find multiple types in the same setting. Here are a couple of examples to highlight this:

Foam Gasket

A foam gasket is composed of two layers of closed-celled urethane foam bonded together using adhesive tape. Foams are generally more expensive than rubbers and silicones.

However, foams offer superior thermal conductivity and sound absorption qualities. Foam Gaskets can be used in a variety of applications, including:

Thermal Insulation

Thermal insulation reduces the amount of heat that passes through an object by reducing its ability to transfer energy from one surface to another.

The most common application for insulating materials is building construction, where it helps keep warm air inside buildings during cold weather or cool air outside during hot summer days.

Sound Absorption

Sound waves travel at different speeds depending on whether they're traveling through solid objects or liquid ones. This means that if you want your home to have quiet rooms, you need to reduce the sound within those spaces.

One way to do this is to place absorbent materials between the source of noise and the room's occupants. A foam gasket will help dampen sounds before they reach people's ears.

O-Ring Gasket

An O-ring gasket consists of many rings of metal with an inner diameter smaller than the outer diameter of the object that's sealed. When compressed between the objects, the ring expands outward until it contacts both sides of the gap. Once contact occurs, the force exerted by the expanding ring causes the opposing surface to deform inward toward the center of the ring, creating a seal.

The use of such seals in various applications was popular for many years and is still popular today. For example, o-rings help sealing shafts or other rotating parts that need maintenance to prevent leakage.

Here, the o-ring provides a barrier against fluid flow along the length of the shaft, while allowing rotation thereof. The o-ring also prevents contaminants from entering into the interior of the housing through which the shaft extends.

PTFE Gasket

PTFE is a fluoropolymer material with many uses, but it works great as a gasket material. PTFE has excellent chemical resistance and is a low-friction coefficient. They also have high-temperature stability, good electrical properties, and outstanding dielectric strength.

It's also nonporous and inert, meaning it does not react with other substances. Thus, these gaskets are most often found in food processing equipment, pharmaceutical manufacturing processes, semiconductor fabrication facilities, and nuclear power plants. They are also used in medical devices because they do not support bacterial growth.

What Is a Gasket? Now You Know!

It's clear gaskets aren't going away any time soon. So next time someone asks you, "what is a gasket?" you'll have all the knowledge you need to impress them to the ends of the Earth! And we know you're as stunned as we were how many places you find gaskets that you never even knew about!

If you need custom gaskets, get in touch with us today and experience gaskets that get our seal of approval!

Scott Chambers

Written by Scott Chambers

As the VP of Marketing for Strouse, Scott oversees the content creation team and drives demand to the sales team. Scott graduated from Coastal Carolina with a degree in Business Management. He then attended the University of Baltimore School of Law, earned his JD, and passed the bar in 2016. In addition to marketing and business development, Scott serves as Strouse's In House Counsel. Scott is currently earning an MBA from Indiana University.

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