How well do you know the difference between an O-ring and a gasket? Can you easily determine the situation in which each type of seal should be used? Each technique is needed in specific situations because they are designed for completely different conditions.

Gaskets vs. O-Rings

What exactly is an O-Ring?

If you envisioned a rubber ring, then you're right! However, they are not that simple. o-rings are precisely molded shapes with a specific profile to fit into a particular channel or groove. These profiles can be of various shapes and the polymer (rubber type) can vary greatly. An infinite number of formulas can be developed to address a specific sealing situation.

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 locations where you can find them.

Hydraulic Seals
Pipe joints
Fluid sealing points in equipment
Oil seals
Fuel systems

How is this different from a gasket?

When you no longer use engineered seals such as O-rings, the next technology used in the sealing family is the gasket. These typically require a flat flange and a bolted connection. Gaskets are by far the most versatile seals, with different shapes, materials, coatings, methods, etc. Depending on the type of material chosen, they can seal over a wide range of temperatures and pressures. Composite (metal-reinforced) materials offer some of the greatest heat and pressure resistance (as far as gaskets are concerned) on the market today. For more information on these materials, see our post What is a metal-reinforced gasket and why do I need one?

How do gaskets with rings compare to O-rings?

As some of you may know, adding a ring to your gasket design adds another layer of protection against increased pressure. Rings make good washers stronger. Check out our post Should I Wear a Ring? (Your gasket, that is) to better understand this technology. Based on our discussion of O-rings today, the next logical question is how do gaskets with rings compare to O-rings? The simple answer is that O-rings require a channel or groove in the flange, while gaskets can use a simpler flat flange. O-rings are often used when pressures are high and channels are present to prevent bursting.