Do I Need an O-ring or a Gasket?

How well do you understand the differences between o-rings and gaskets? Can you readily identify situations where each type of seal should be used? There are specific situations where each technology is needed because they are designed for completely different conditions.

Today, we thought we’d dig a little deeper into gasket vs. o-ring.

Gasket vs. O-ring

What exactly is an o-ring?

If you are envisioning a rubber ring, you are right! However, they aren’t quite that simple. An O-ring is a precisely molded shape with a specific profile to fit into a specific channel or groove. These profiles can be various shapes and the polymer (type of rubber) can also vary greatly. Infinite formulas can be made to address specific sealing situations.

Where and how are they used?

O-rings are known for their ability to seal extremely high pressures. Here is a short list of some of the more common places where you would find them.

    • Hydraulic seals
    • Pipe joints
    • Fluid seal points in equipment
    • Oil seals
    • Fuel systems

How does this differ from gaskets?

When you move away from engineered seals like o-rings, the next technology to use in the sealing family is a gasket. These typically require a flat flange and a bolted joint. Gaskets are by far the most versatile seal, with different shapes, materials, coatings, methods, etc. Depending on the type of material chosen, they can seal at a wide range of temperatures and pressures. Composite (metal reinforced) materials provide some of the strongest heat and pressure resistance (as far as gaskets go) in the market today. For more information about these materials, view our post What Is a Metal Reinforced Gasket and Why Do I Need One?

How do gaskets with rings compare to an o-ring?

Some of you may know that adding a ring to your gasket design adds another layer of protection against increased pressure. Rings make a good gasket even stronger. View our post Should I Put a Ring On It? (Your Gasket, That Is) to get a better understanding of this technology. In light of our discussion today regarding o-rings, the next logical question is how does a gasket with a ring compare to an o-ring? The simple answer is that the O-ring requires a channel or groove in the flanges, while a gasket can perform with a simpler, flat flange. O-rings are typically used when pressures are higher, with the channel present to prevent blowout.

Choose Your Technology

Once you truly understand all of the engineering behind all of the various sealing technologies, the decision on what should be used is very clear. Until then, talk to your contacts in the sealing industry to better understand what your options are for a specific application.

Until next time!Hi-Tex Product Comparison

The Most Commonly Used Gasket Materials & Why You Need Them All

Imagine this scenario….you get called into the office of your boss (or project engineer, purchasing manager, co-worker, etc.) and he (or she) asks (or tells) you to do some research and find the best gasket material you can for {insert application}. It needs to seal, have great recovery properties, stand up to high heat and scrubbing, and oh…it needs to not cost too much. You immediately sign on for the task and walk out of her (or his) office, go back to your computer, sit down and google.

You are feeling pretty confident (after all, you are a Google Master) and type in “gasket material”. As the results load and you start clicking through, your smile begins to fade. It seems like there are hundreds of different types of material and they all claim to seal, have great recovery properties, stand up to high heat and scrubbing and are a low cost.

Your task might not be as easy as you initially thought, but have no fear. You have stumbled across this blog post and we will get you moving in the right direction (we can’t do all of the work for you, but we’ll do what we can).

The most commonly used gasket materials can be listed as: fiber, rubber, metal, and composite laminates.

The first question you need to answer is – What are you trying to seal?

Let’s Talk Seals

FLUIDS: Sealing fluids generally is performed by rubber or fiber materials. Rubber comes in many forms (sheet, molded, O-rings, coatings, etc.)  Fiber is generally a sheet material that comes in many varieties depending on the factors of the joint. Composite materials can be a combination of rubber/fiber/metal generally a laminate suited for fluid sealing with a metal core for support.

GASES: Generally, exhaust applications and other gas sealing joints with high temperatures use metal or composite materials. These products resist degradation over time due to the heat exposure, flange motion and thermal cycles, and maintain a seal. Metal gaskets require very smooth flange conditions while composite products are more tolerant of rougher surfaces. In composites, the metal core provides support and, with tanged products, a mechanical bond. Composites also tend to be the most forgiving with flange flatness, surface irregularities, and varying flange loads.

Another question to ask – What are other details of the joint?

Let’s Talk Details

Other details to consider in a gasket material choice are: quantity and fabrication method. With small quantities, fabrication methods such as flash cutting, waterjet, and laser-cutting can be used in lieu of investing in a tool or die to cut parts.

Decisions, Decisions

As you can see, these gasket materials all have their strengths and weaknesses. Each of these materials excels in certain applications, so it is important not to get tunnel vision and try to use one type of material across all of your seal points just because “it worked really well for us in the past”.

We encourage you to talk to your gasket material manufacturer about all of these types of materials to aid you in your decision making process. If your preferred supplier doesn’t make a certain material, or is pushing  you into something that you aren’t certain is the right fit for you, don’t hesitate to shop around for your test material. The right material in the right application makes all the difference in performance.

As always, let us know if we can answer any questions for you!

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