It is a common misconception that gaskets and seals are the same thing.
While they do have similar functions in preventing leaks, gaskets and seals have different applications. In general, gaskets are used as static seals between flat surfaces, such as joints, while seals are used in dynamic environments between moving parts, such as rotating shafts, pumps and engines.
What are gaskets?
Aviation rubber gaskets in various shapes
Gaskets are rings or sheets of flexible material used in static applications to seal joints, flanges and other mating surfaces to prevent leakage.
Depending on the material and application, gaskets can be produced using a variety of manufacturing techniques, including:
Rubber extrusion
Hot vulcanization and cold bonded splicing
Compression, injection and transfer molding
Precision slitting
Custom die-cutting
Waterjet cutting
Gaskets and seals can be found in virtually all applications and industries, including oil and gas, manufacturing and industrial applications, pulp and paper production, and agricultural equipment.
Worn or damaged gaskets are easily replaced. It is often recommended that gaskets be replaced when disassembling and reassembling equipment.
How often should gaskets be replaced?
New gaskets should be used each time any equipment is disassembled and then reassembled.
What industries use gaskets?
Gaskets are used in many industries, including oil and gas, pulp and paper, power generation and transportation.
What are seals?
Rubber seals made from aircraft rubber
Seals are a broader category that includes O-rings, valve stem seals, rotary seals and mechanical seals. Unlike gaskets, which are typically used in static applications, seals are found in more active environments such as motors, engines, pumps and rotating shafts. Seals tend to be flat and round, with an angled rubber inner ring surrounded by a metal outer ring. The sloping angle of the seal's inner layer helps prevent leakage in dynamic applications. Seals are typically used to prevent leakage between two moving parts and to prevent particles and contaminants from intruding into the system.
The process of replacing a broken or damaged seal can be very complex. Not only the seal, but the entire assembly may need to be disassembled to gain access to the seal and allow for replacement.
What are seals used for?
Common uses for seals include preventing leaks from occurring at the end of the shaft coming out of the cap and sealing hydraulic lines. These types of seals are usually molded or machined products. Seals are often used in bearings, which are basically just a ball bearing surrounded by a rubber seal, which prevents it from leaking and sometimes reduces the noise generated during operation.
How are seals installed?
Seals are usually installed by using a press to fit them into the holes and then tapping them further with a hammer. Lubrication is usually required to prevent the crankshaft from damaging the seal as it passes through it.
When should I replace a seal?
When a seal is damaged, the entire bearing must be replaced, not just the seal.
Gasket and Seal Materials
Seals and gaskets can be made from a variety of materials, depending on their intended use. Common materials used to make gaskets and seals include
Buna 'N' (nitrile rubber)
CSR (Hypalon®)
EPDM rubber
Fluorosilicone
Fluoroelastomer (FKM)
Natural Rubber (Polyisoprene)
Neoprene
Polyurethane
Silicones
Synthetic Polyisoprene
Thermoplastic Rubber (TPR)
Fluoroelastomer®
All of NNK's materials can be formulated and customized to meet the needs of your specific application.
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Quality Sealing Solutions from NNK
At NNK, we pride ourselves on providing the highest quality rubber gaskets and seals in the industry. We manufacture your gaskets and seals to meet the most detailed specifications. Whether you need a simple gasket or a complex sealing solution, our knowledgeable and experienced engineers and experts will help you find the best seal material and design for your needs.
Bonded Seal 