Top Seal Gasket - Glossary

Aramid Aramid fibers are a class of heat-resistant and strong synthetic fibers. The name is a portmanteau of "aromatic polyamide". They are fibers in which the chain molecules are highly oriented along the fiber axis, so the strength of the chemical bond can be exploited. Aromatic polyamides were first introduced in commercial applications in the early 1960s, with a meta-aramid fiber produced by DuPont as HT-1 and then under the trade name Nomex. This fiber, which handles similarly to normal textile apparel fibers, is characterized by its excellent resistance to heat, as it neither melts nor ignites in normal levels of oxygen. (source and more info)

ASME The American Society of Mechanical Engineers.

ASTM The American Society for Testing and Materials.

Bolt Load The compressive force from the bolts on the flange that compresses the gasket material to allow it to conform to the imperfections in the flange face and ultimately seal the joint.

Buna Nitrile Rubber. Also known as Buna-N, Perbunan, acrylonitrile butadiene rubber, and NBR, is a synthetic rubber copolymer of acrylonitrile (ACN) and butadiene. Nitrile butadiene rubber (NBR) is a family of unsaturated copolymers of 2-propenenitrile and various butadiene monomers (1,2-butadiene and 1,3-butadiene). (source and more info)

Compressibility How much thickness does the gasket lose under a given load.  Or, roughly how hard or soft is the material.  Soft materials like many synthetic rubbers or cork, can compress a lot and can be used with lower flange loads. Fiber-based gaskets, metal gaskets, and others that are harder, compress much less and thus require higher loads to create a seal.

Creep Relaxation A measure of essentially how much the gasket spreads when force from flange bolts is applied. This is related to how much torque is retained from the initial bolt load. Lower numbers mean there is less spreading and thus more sustained force on the bolt and more torque is retained. Creep relaxation is closely related to the thickness of the gasket material.

Elasticity Ability to resist a deforming force and return back to original shape and size.

Elastomer Essentially, rubber or synthetic rubber. It is a polymer with both viscosity and elasticity. (more info)

FKM FKM is the designation for about 80% of fluoroelastomers as defined in ASTM D1418. All FKMs contain vinylidene fluoride as a monomer. Originally developed by DuPont® (Viton®), FKMs are today also produced by Daikin®, 3M® and others. Viton® is now manufactured by Chemours®. Fluoroelastomers are more expensive than neoprene or nitrile rubber elastomers. They provide additional heat and chemical resistance. FKMs can be divided into different classes on the basis of either their chemical composition, their fluorine content or their crosslinking mechanism. (source and more info)

Flange A flange is a physical device to connect pipes, pumps or valves to create a piping system. The flange also allows easier access for cleaning and inspection, and provides a logical place for system modification. Most often, flanges are screwed, but can be welded. In most piping systems, flanges are joined together with a gasket between them to provide a seal. (more info)

Full Face Refers to a gasket shape where the gasket material includes the face of the flange. Bolt holes are pre-cut into the gasket to allow installation. For installation, the joints must be disassembled.

ID Inside Diameter - Or distance across the hole on the inside of the gasket.

Neoprene Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene exhibits good chemical stability and maintains flexibility over a wide temperature range. Neoprene is sold either as solid rubber or in latex form, and is used in a wide variety of applications. (source and more info)

OD Outside Diameter - Or distance across the outside of the gasket.

PTFE (Teflon®) Simply, PTFE is a plastic incredibly resistant to chemicals, making it an ideal gasket material in certain applications. Technically, polytetrafluoroethylene is a fluoropolymer (contains flourine and carbon) originally developed by DuPont® in 1938. PTFE has one of the lowest coefficients of friction of any solid, making it “non-stick”. It is non-reactive, partly because of the strength of carbon–fluorine bonds, and so it is often used in containers and pipework for reactive and corrosive chemicals. (more technical info).

Recovery A measurement of how much a material will return back to its original form as force is removed. After a system has some natural relaxation, recovery is important to maintain a seal.

Ring Gasket Refers to a gasket shape where the gasket material does not include or cover the bolt areas of a flange. While providing an equally satisfactory seal, ring gaskets may be harder to align during installation.

Viscosity The property of a fluid that resists the force tending to cause the fluid to flow. In simpler terms, how much does a fluid or material resist deformation. One can think of fluid "thickness" as a parallel concept.