Mon compte

connexion

inscription

   Publicité ▼


 » 
allemand anglais arabe bulgare chinois coréen croate danois espagnol espéranto estonien finnois français grec hébreu hindi hongrois islandais indonésien italien japonais letton lituanien malgache néerlandais norvégien persan polonais portugais roumain russe serbe slovaque slovène suédois tchèque thai turc vietnamien
allemand anglais arabe bulgare chinois coréen croate danois espagnol espéranto estonien finnois français grec hébreu hindi hongrois islandais indonésien italien japonais letton lituanien malgache néerlandais norvégien persan polonais portugais roumain russe serbe slovaque slovène suédois tchèque thai turc vietnamien

définition - gasket

gasket (n.)

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

   Publicité ▼

Merriam Webster

GasketGas"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.) (a) The plaited hemp used for packing a piston, as of the steam engine and its pumps. (b) Any ring or washer of made of a compressible material, used to make joints impermeable to fluids.

   Publicité ▼

définition (complément)

voir la définition de Wikipedia

synonymes - gasket

gasket (n.)

packing

locutions

dictionnaire analogique

Wikipedia

Gasket

                   
  Some seals and gaskets
1. 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, such as gasket paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, Polytetrafluoroethylene (otherwise known as PTFE or Teflon) or a plastic polymer (such as polychlorotrifluoroethylene).

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 fills 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 σy, the material's yield strength). This is typical of some "ring joints" (RJ) or some other metal gasket systems such as those made by Graylock (an Oceaneering International company). These joints are known as R-con and E-con compressive type joints.

  Polytetrafluoroethylene (PTFE) gasket

Contents

  Properties

  Compressed fiber gasket

One of the more desirable properties of an effective gasket in industrial applications for compressed fiber gasket material is the ability to withstand high compressive loads. Most industrial gasket applications involve bolts exerting compression well into the 14 MPa (2000 psi) range or higher. Generally speaking, there are several truisms that allow for best gasket performance. One of the more tried and tested is: "The more compressive load exerted on the gasket, the longer it will last".

There are several ways to measure a gasket material's ability to withstand compressive loading. The "hot compression test" is probably the most accepted of these tests. Most manufacturers of gasket materials will provide or publish the results of these tests.

  Gasket design

Gaskets come in many different designs based on industrial usage, budget, chemical contact and physical parameters:

  Sheet gaskets

The premise is simple in that a sheet of material has the gasket shape "punched out" of it. This leads to a very crude, fast and cheap gasket. In previous times the material was compressed asbestos, but in modern times a fibrous material such as graphite is used. These gaskets can fill many chemical requirements based on the inertness of the material used and fit many budgetary restraints. Common practice prevents these gaskets from being used in many industrial processes based on temperature and pressure concerns.

(source: Indicative list of Hong Kong Convention, it shows out that asbestos containing gaskets are manufactured at last till mid of this year in China and have been sold worldwide)

  Solid material gaskets

The idea behind solid material is to use metals which cannot be punched out of sheets but are still cheap to produce. These gaskets generally have a much higher level of quality control than sheet gaskets and generally can withstand much higher temperatures and pressures. The key downside is that a solid metal must be greatly compressed in order to become flush with the flange head and prevent leakage. The material choice is more difficult; because metals are primarily used, process contamination and oxidation are risks. An additional downside is that the metal used must be softer than the flange — in order to ensure that the flange does not warp and thereby prevent sealing with future gaskets. Even so, these gaskets have found a niche in industry.

  Spiral-wound gaskets

Spiral-wound gaskets comprise a mix of metallic and filler material. Generally, the gasket has a metal (normally carbon rich or stainless steel) wound outwards in a circular spiral (other shapes are possible) with the filler material (generally a flexible graphite) wound in the same manner but starting from the opposing side. This results in alternating layers of filler and metal. The filler material in these gaskets acts as the sealing element, with the metal providing structural support.

These gaskets have proven to be reliable in most applications, and allow lower clamping forces than solid gaskets, albeit with a higher cost.

  Constant seating stress gaskets

The constant seating stress gasket consists of two components; a solid carrier ring of a suitable material, such as stainless steel, and two sealing elements of some compressible material installed within two opposing channels, one channel on either side of the carrier ring. The sealing elements are typically made from a material (expanded graphite, expanded polytetraflouroethylene (PTFE), vermiculite, etc.) suitable to the process fluid and application. Constant seating stress gaskets derive their name from the fact that the carrier ring profile takes flange rotation (deflection under bolt preload) into consideration. With all other conventional gaskets, as the flange fasteners are tightened, the flange deflects radially under load, resulting in the greatest gasket compression, and highest gasket stress, at the outer gasket edge.

Since the carrier ring used in constant seating stress gaskets take this deflection into account when creating the carrier ring for a given flange size, pressure class, and material, the carrier ring profile can be adjusted to enable the gasket seating stress to be radially uniform across the entire sealing area. Further, because the sealing elements are fully confined by the flange faces in opposing channels on the carrier ring, any in-service compressive forces acting on the gasket are transmitted through the carrier ring and avoid any further compression of the sealing elements, thus maintaining a 'constant' gasket seating stress while in-service. Thus, the gasket is immune to common gasket failure modes that include creep relaxation, high system vibration, or system thermal cycles. The fundamental concept underlying the improved sealability for constant seating stress gaskets are that (i) if the flange sealing surfaces are capable of attaining a seal, (ii) the sealing elements are compatible with the process fluid and application, and (iii) the sufficient gasket seating stress is achieved on installation necessary to affect a seal, then the possibility of the gasket leaking in-service is greatly reduced or eliminated altogether.

The Patent for the constant seating stress gasket is held by JJENCO, Inc., Charlotte, North Carolina, USA. Various constant seating stress gasket designs for different applications are sold by that company under the tradename 'PerfectSeal'.

  Double-jacketed gaskets

Double-jacketed gaskets are another combination of filler material and metallic materials. In this application, a tube with ends that resemble a "C" is made of the metal with an additional piece made to fit inside of the "C" making the tube thickest at the meeting points. The filler is pumped between the shell and piece. When in use the compressed gasket has a larger amount of metal at the two tips where contact is made (due to the shell/piece interaction) and these two places bear the burden of sealing the process. Since all that is needed is a shell and piece, these gaskets can be made from almost any material that can be made into a sheet and a filler can then be inserted. This is an effective option for most applications.

  Kammprofile gaskets

Kammprofile gaskets are used in many older seals since they have both a flexible nature and reliable performance. Kammprofiles work by having a solid corrugated core with a flexible covering layer. This arrangement allows for very high compression and an extremely tight seal along the ridges of the gasket. Since generally the graphite will fail instead of the metal core, Kammprofile can be repaired during later inactivity. Kammprofile has a high capital cost for most applications but this is countered by long life and increased reliability.

  Flange gasket

A flange gasket is a type of gasket made to fit between two sections of pipe that are flared to provide higher surface area.

Flange gaskets come in a variety of sizes and are categorized by their inside diameter and their outside diameter.

There are many standards in gasket for flanges of pipes. The gaskets for flanges can be divided in major 4 different categories:

  1. Sheet gaskets
  2. Corrugated metal gaskets
  3. Ring gaskets
  4. spiral wound gaskets

Sheet gaskets are simple, they are cut to size either with bolt holes or without holes for standard sizes with various thickness and material suitable to media and temperature pressure of pipeline.

Ring gaskets also known as RTJ. They are mostly used in offshore oil- and gas pipelines and are designed to work under extremely high pressure. They are solid rings of metal in different cross sections like oval, round, octagonal etc. Sometimes they come with hole in center for pressure equalization.

Spiral wound gaskets are also used in high pressure pipelines and are made with stainless steel outer and inner rings and a center filled with spirally wound stainless steel tape wound together with graphite and PTFE, formed in V shape. Internal pressure acts upon the faces of the V, forcing the gasket to seal against the flange faces.

  Improvements

Many gaskets contain minor improvements to increase lifespan or acceptable operating conditions:

  • A common improvement is an inner compression ring. A compression ring allows for higher flange compression while preventing gasket failure. The effects of a compression ring are minimal and generally are just used when the standard design experiences a high rate of failure.
  • A common improvement is an outer guiding ring. A guiding ring allows for easier installation and serves as a minor compression inhibitor. In some alkylation uses these can be modified on Double Jacketed gaskets to show when the first seal has failed through an inner lining system coupled with alkylation paint.

  See also

  Sources

  1. Bickford, John H.: An Introduction to the Design and Behavior of Bolted Joints, 3rd ed., Marcel Dekker, 1995, pg. 5
  2. Latte, Dr. Jorge and Rossi, Claudio: High Temperature Behavior of Compressed Fiber Gasket Materials, and an Alternative Approach to the Prediction of Gasket Life, FSA presented Paper, 1995, pg. 16

  External links

   
               

 

Toutes les traductions de gasket


Contenu de sensagent

  • définitions
  • synonymes
  • antonymes
  • encyclopédie

  • definition
  • synonym

   Publicité ▼

dictionnaire et traducteur pour sites web

Alexandria

Une fenêtre (pop-into) d'information (contenu principal de Sensagent) est invoquée un double-clic sur n'importe quel mot de votre page web. LA fenêtre fournit des explications et des traductions contextuelles, c'est-à-dire sans obliger votre visiteur à quitter votre page web !

Essayer ici, télécharger le code;

SensagentBox

Avec la boîte de recherches Sensagent, les visiteurs de votre site peuvent également accéder à une information de référence pertinente parmi plus de 5 millions de pages web indexées sur Sensagent.com. Vous pouvez Choisir la taille qui convient le mieux à votre site et adapter la charte graphique.

Solution commerce électronique

Augmenter le contenu de votre site

Ajouter de nouveaux contenus Add à votre site depuis Sensagent par XML.

Parcourir les produits et les annonces

Obtenir des informations en XML pour filtrer le meilleur contenu.

Indexer des images et définir des méta-données

Fixer la signification de chaque méta-donnée (multilingue).


Renseignements suite à un email de description de votre projet.

Jeux de lettres

Les jeux de lettre français sont :
○   Anagrammes
○   jokers, mots-croisés
○   Lettris
○   Boggle.

Lettris

Lettris est un jeu de lettres gravitationnelles proche de Tetris. Chaque lettre qui apparaît descend ; il faut placer les lettres de telle manière que des mots se forment (gauche, droit, haut et bas) et que de la place soit libérée.

boggle

Il s'agit en 3 minutes de trouver le plus grand nombre de mots possibles de trois lettres et plus dans une grille de 16 lettres. Il est aussi possible de jouer avec la grille de 25 cases. Les lettres doivent être adjacentes et les mots les plus longs sont les meilleurs. Participer au concours et enregistrer votre nom dans la liste de meilleurs joueurs ! Jouer

Dictionnaire de la langue française
Principales Références

La plupart des définitions du français sont proposées par SenseGates et comportent un approfondissement avec Littré et plusieurs auteurs techniques spécialisés.
Le dictionnaire des synonymes est surtout dérivé du dictionnaire intégral (TID).
L'encyclopédie française bénéficie de la licence Wikipedia (GNU).

Copyright

Les jeux de lettres anagramme, mot-croisé, joker, Lettris et Boggle sont proposés par Memodata.
Le service web Alexandria est motorisé par Memodata pour faciliter les recherches sur Ebay.
La SensagentBox est offerte par sensAgent.

Traduction

Changer la langue cible pour obtenir des traductions.
Astuce: parcourir les champs sémantiques du dictionnaire analogique en plusieurs langues pour mieux apprendre avec sensagent.

 

6302 visiteurs en ligne

calculé en 0,078s

Je voudrais signaler :
section :
une faute d'orthographe ou de grammaire
un contenu abusif (raciste, pornographique, diffamatoire)
une violation de copyright
une erreur
un manque
autre
merci de préciser :