Aircraft Components: The O-Ring

The concept of the o-ring is very similar to that of a gasket. Both are specially designed seals that fill space between two surfaces in order to prevent leakage when a mechanism is static or compressed. An O-ring is designed to act as a seal to prevent fluid leakage in a variety of practicalities, including aircraft pneumatic and hydraulic systems.

Instead of the metal-based materials of a gasket, an o-ring is usually made of elastomers or relatively soft materials including silicone, neoprene, PTFE plastics, and more. The materials must be able to withstand varying temperatures and volatile operating environments. They are commonly designed alongside the hardware they are to be installed with, to ensure the dimensions of both are suited to the intended leakage prevention.

The o-ring, as its name suggests, is a toroid shape. The o-ring is rounded on all sides, and its shape forms a rounded cross-section which compresses diametrically. It sits within two metal hardware surfaces, and all together make up what is called a “gland”. As pressure rises within a sealing gland, the o-ring is compressed and attempts to shift to low-pressure areas. This process squeezes the seal altogether, and the resulting force binds the O-ring with the inner and outer walls of the gland, increasing sealing force and preventing fluid leakage.

Though relatively simple in design, the component can fail under certain parameters, and cause complications within a system. O-ring failure can occur under circumstances of extreme pressurization, excessive wear, chemical swelling, installation damage, and more. As such, it is important to remain up to date on manufacturer recommendations and specifications for o-ring inspection.

Overall, the o-ring is a versatile component that has been used in various industries for decades. It continues to be an important mechanism in aircraft pneumatic and hydraulic systems.

At NSN Fulfillment, owned and operated by ASAP Semiconductor, we can help you find all the aircraft fasteners and NSN parts suppliers you need, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we’re always available and ready to help you find the parts and equipment you need, 24/7x365. For a quick and competitive quote, email us at or call us at +1-714-705-4780.


September 27, 2018

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