What is "gasket"

Gasket \Gas"ket\, n. [Cf. F. garcette, It. gaschetta, Sp. cajeta caburn, garceta reef point.]

1. (Naut.) A line or band used to lash a furled sail securely. Sea gaskets are common lines; harbor gaskets are plaited and decorated lines or bands. Called also casket.

2. (Mech.)

   1. The plaited hemp used for packing a piston, as of the steam engine and its pumps.

   2. Any ring or washer of made of a compressible material, used to make joints impermeable to fluids.

1620s, caskette "small rope or plaited coil used to secure a furled sail," of uncertain origin, perhaps from French garcette "little girl, maidservant," diminutive of Old French garce (13c.) "young woman, young girl; whore, harlot, concubine," fem. of garçon (see garcon). Sense of "packing (originally of braided hemp) to seal metal joints" first recorded 1829.

n. 1 Any mechanical seal that serves to fill the space between two objects, generally to prevent leakage between the two objects while under compression. 2 A material which may be clamped between faces and acts as a static seal. Gaskets may be cut, formed, or molded to the desired configuration. 3 Any of a wide variety of seals or packings used between matched machine parts or around pipe joints to prevent the escape of a gas or fluid.

n. seal consisting of a ring for packing pistons or sealing a pipe joint

thumb|sright|250px|Some seals and gaskets1. o-ring
2. fiber washer
3. paper gaskets
4. cylinder head gasket A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression.

Gaskets allow "less-than-perfect" mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials.

Gaskets for specific applications, such as high pressure steam systems, may contain asbestos. However, due to health hazards associated with asbestos exposure, non-asbestos gasket materials are used when practical.

It is usually desirable that the gasket be made from a material that is to some degree yielding such that it is able to deform and tightly fill the space it is designed for, including any slight irregularities. A few gaskets require an application of sealant directly to the gasket surface to function properly.

Some (piping) gaskets are made entirely of metal and rely on a seating surface to accomplish the seal; the metal's own spring characteristics are utilized (up to but not passing σ, the material's yield strength). This is typical of some "ring joints" (RTJ) or some other metal gasket systems. These joints are known as R-con and E-con compressive type joints. thumb|sright|250px|Polytetrafluoroethylene (PTFE) gasket

In sailing, gaskets are lengths of rope or fabric used to hold a stowed sail in place. In modern use, the term is usually restricted to square-rigged ships, the equivalent items on yachts being referred to by the more prosaic "sail ties".

On most ships, gaskets are made of rope. They are attached to the top of the yard and, left loose, would hang behind the sail. Gaskets should never be left dangling, however, so when the sail is set they are brought around underneath the yard and up the back of it and then tied to the jackstay (metal rod) where they originated. Alternatively, longer gaskets - particularly the clew gaskets described below - can be secured using a gasket coil. When the sail is to be stowed it is first folded and bagged neatly within itself, pulled onto the top of the yard, and then the gaskets are brought round over it and secured to the jackstay to hold it in place. Gaskets should be tied with a slippery hitch to enable them to be let off quickly, though if the yard is large there may only be enough rope to form a clove hitch when the gasket is brought round it.

Most ships are equipped with clew gaskets at the outer ends of the yards. These do not pass around the sail, but through a shackle or ring on the blocks of the sheet. Pulled tight and secured to the jackstay or the yard's lift, this takes the load off the clewline and sail, and should allow the blocks to be lifted higher, dragging the sail down less and enabling a neater stow.

A gasket (correct terminology is a "joint" made from "jointing material") is a mechanical seal that fills the space between two mating surfaces.

Gasket may also refer to:

• Flange gasket, a type of gasket made to fit between two sections of pipe
• Head gasket, a gasket used in internal combustion engines
• Gasket (sailing), a rope used to hold a stowed sail in place
• Apollonian gasket, a fractal generated from triples of circles
• Sierpinski gasket, a fractal generated from triangles
• The Gaskets, U.S. synth-pop/rock band