Engineering seals are critical components used to prevent leakage of fluids and gases in mechanical systems. They are essential in applications ranging from hydraulic systems and pumps to engines and industrial process equipment.
This page provides an overview of the main types of engineering seals, including O-rings, rotary seals, mechanical seals, packing seals and gasket seals, with links to detailed technical resources for each type.
Engineering seals are devices used to contain fluids and gases within mechanical systems while preventing leakage and contamination. They are designed to operate under a wide range of pressures, temperatures and motion conditions.
Seals are generally classified into two main categories:
O-ring seals are one of the most common sealing solutions used in hydraulic and pneumatic systems. They are simple, economical toroidal seals used in both static and dynamic applications. An o-ring is a doughnut-shaped, elastomeric seal that prevents leakage by being compressed in a groove, deforming its circular cross-section to fill the gap between two parts. It is a simple, common, and economical seal used in both static (non-moving) and dynamic (moving) applications, such as in pumps, valves, and hydraulic systems. Its sealing power comes from its ability to return to its original shape after being compressed, which creates a tight seal that can be made more robust under pressure.
O Rings
Rotary shaft seals are used to seal rotating shafts and prevent oil leakage and contamination.Elastomer lip seal variants, labyrinth seals etc. Rotary seals (also called shaft seals or rotary shaft seals) are components designed to seal the interface between stationary and rotating parts—typically a shaft and its housing—to prevent the leakage of fluids (like oil or grease) and the ingress of contaminants (like dust or water).
Rotary Seals
Mechanical seals are used in pumps and rotating equipment to prevent fluid leakage under high pressure. Engineered mechanical seals used for high speeds. Mechanical seals are precision-engineered devices used to prevent fluid leakage where a rotating shaft passes through a stationary housing — such as in pumps, compressors, mixers, or agitators. They are an upgrade over traditional packing glands, offering higher reliability, longer service life, and reduced maintenance.
Mechanical Seals
Packings used for pump and valve glands . Packing seals (also known as gland packing or stuffing box packing) are one of the oldest and simplest methods of sealing a rotating or reciprocating shaft to prevent leakage of fluids. They are made from flexible materials—such as graphite, PTFE, or natural fibers—compressed around the shaft inside a chamber called a stuffing box.
Packing Seals
Seals for a wide range of face and flange seals. Gasket seals — often simply called gaskets — are static sealing elements used to fill the space between two stationary (non-moving) surfaces to prevent fluid or gas leakage under compression. They are one of the most common and essential sealing components in mechanical systems, found in everything from car engines to industrial pipelines.
Gasket SealsSelecting the correct seal depends on several engineering factors:
Each seal type offers different advantages depending on the application, which is why understanding the differences between seal types is essential for reliable system design.
Engineering seals are components used to prevent leakage of fluids or gases between mechanical parts.
The main types include O-rings, rotary seals, mechanical seals, packing seals and gaskets.
Static seals are used between non-moving parts, while dynamic seals are used where movement occurs.
Mechanical seals are used in pumps, compressors and rotating equipment to prevent leakage.
O-rings are the most widely used seals due to their simplicity and low cost.