O-ring VS Gasket: Which One Should You Use?

In this article, you’ll learn more about o-rings and gaskets. Specifically, their differences and their applications so you’ll know what to choose between them.

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O-rings and gaskets are sealing products that can keep out air or liquid. Both gaskets and O-rings are made using flexible materials, but gaskets can also be made out of other rigid polymers and metals. These two usually sit between 2 or more parts. You can use both of them in motors, machines, and various fixtures and plumbing. On the surface, it seems like they are the same. But you can’t interchange these two.

o ring vs. gasket

What is an O-ring?

An O-ring is a type of gasket you can use as a mechanical seal. Although it can come in different sizes, thicknesses, or dimensions, it only has one shape – a donut shape. It’s a circular elastomer piece with a hollow center that you can also refer to as a packing joint.


The purpose of o-rings is to prevent fluid or gas leakage and to create a sealed surface where 2 or more parts meet. It usually sits in a groove where another part will join. When the parts join together, it puts pressure on the O-ring in the grooved part. The sealing happens because the pressure on the o-ring makes it mold itself in the surrounding space.

O-rings are available in different elastomer materials like silicone rubber, nitrile rubber, and fluoropolymers. To choose the right material, you have to consider the application. This will also help define the elastomer’s hardness, thickness, size, and other qualities. The bottom line is that it should perform well under the right operational and environmental situations.


Despite the pressure, the elastomer material of the o-ring allows it to maintain the integrity of its shape. It can withstand an extreme pressure of up to 5,000 psi (pounds per square inch). It retains its shape even if there’s an additional vibration from the mechanical device. This makes it a very effective sealing product to keep liquids, air, and gas from escaping.

Among the typical applications of o-rings are aerospace and automotive. This includes the following:

  • Food containers and processing equipment
  • Fuel systems
  • HVAC systems (Heating, Ventilation, and Air Conditioning)
  • Hydraulics
  • Medical and pharmaceutical equipment or devices
  • Oil seals for engines and devices
  • Pipe joints

What is a Gasket?

A gasket is a flat piece of material that sits between two flat surfaces and serves as a mechanical seal designed to provide a liquid-tight seal. But instead of having a looped circular shape, it’s usually a flat material. The main shape of gaskets is usually circular, too. But it can come in various shapes like rectangles, squares, ovals, triangles, or any other shape.

Rubber Gaskets and Seals Die Cut

It’s not like o-rings that only use elastomer as their material – allowing it to retain its shape despite being up under pressure. Gaskets use elastomer, but it also uses other materials like corks, foam, metals, complex polymer, etc.

The choice of shape, size, and material will mostly depend on the purpose of the gasket. If you plan to make it sit between the engine block and cylinder head of an automotive engine, you’re better off using a metal gasket.

While gaskets can use hard materials, it’s still essential that it has compression functionality. This means it has to be pliable enough to conform to the surface where it sits.

When using hard materials, the gasket must fit the design specifications. That’s how it can fit between two surfaces to create a liquid-tight seal. This prevents gas or liquid from leaking and contaminating other parts of the mechanical system.

Food Processing Gaskets

The typical applications of gaskets include the following:

  • Aerospace industry
  • Automotive and other modes of transportation
  • Electrical motors and devices
  • Electronics
  • Food and beverage applications
  • Handheld communication devices
  • Medical devices and equipment
  • Paper and pulp
  • Power generators and transformers
  • Telecommunication devices
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Main Differences between an O-ring and a Gasket

A lot of sealing products are usually interchangeable. However, O-rings and gaskets aren’t one of them. Although both are mechanical seals, there are specific differences that you should focus on.

O-rings and Gaskets

These differences will help you identify which of the two is ideal for your application.

  • O-rings have a looped and circular shape. Gaskets are flat seals that sit between two flat surfaces. While all o-rings are gaskets, not all gaskets are o-rings.
  • O-rings only use flexible materials because they require flexibility in their application. Gaskets can use elastomers and other materials like complex polymer, metal, cork, foam, etc.
  • O-rings can only be circular. Gaskets can take on other shapes – depending on their application. The material that gaskets use can be pliable enough to allow customization into various mating surfaces – no matter how complex.

2 Considerations before Choosing between O-rings and Gaskets


If you want to know which mechanical seal to use, there are 2 essential things you need to consider.

The first is the shape of the seal needed. If the mechanical device’s mating surface has a groove, then o-rings will work best. But if the seal will sit on a flat surface, a gasket is best for the application. If the mating surface also requires a specific shape, that will tell you if you should go for o-rings and gaskets.

The second consideration is the pressure and temperature that the mechanical seal will deal with. Both gaskets and o-rings can work well in a wide range of temperatures. However, gaskets can withstand higher temperatures, while o-rings are the best choice for extreme-pressure applications.

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O-rings and gaskets are both ideal mechanical seals. But you must know the application first to decide which of the two you can use. For whatever purpose, Hongju Silicone can help you produce the proper rubber mechanical seal that fits your design and requirements.

Hongju Silicone has years of experience in molded silicone rubber products. Being one of the best suppliers and manufacturers of O-rings products in China, you can request complex designs, and we can meet those requirements for you.

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Hey there, I’m David!

I’m the founder of Hongju Silicone. I have been in this field for more than two decades. If you are looking for custom-made silicone rubber products, feel free to ask me any questions.

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