ASTM F118-13

Designation: F118 − 13Standard Definitions of Terms Relating toGaskets1This standard is issued under the fixed designation F118; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (´) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This standard is a compilation of terminology, relateddefinitions, and descriptions of terms used in the gasketindustry. Included terms are those used to define materials,testing technology, and testing results related to gaskets.2. Terminologyadhesion—the measurable attraction or bonding of a gasketmaterial to a surface after the application of temperature, orcompressive stress, or both. F607annulus—a cut gasket shape consisting of two concentriccircles of known geometry.binder—a component of certain gasket materials, which so-lidifies the structure, imparts uniform adhesion to surfaces,and has an impact on the pore structure and resiliency.blowout, gasket—the sudden release of internal pressure by agasket sealing a flange with a given stress applied. Theinternal pressure needed to create a blowout is also known asthe blowout pressure. F434classification—a means of specifying categories of gasketmaterials according to composition, method of manufacture,mechanical characteristics, and physical characteristics.F104combustibles—components of gasket material which are loston ignition at a given temperature. F495compressed thickness—the measured thickness of a gasketmaterial with a known compressive stress applied.compressibility—in compressibility/recovery testing of gasketmaterials, the difference between the specimen thicknessunder preload and thickness under total load, divided by thethickness under preload, expressed as a percent. F36, F806compressive strength/crush extrusion resistance—maximum compressive stress before crush occurs at aspecified temperature without regard for leakage. F1574compressive yield—the point which the slope of the relation-ship between applied stress and deformation of a gasketmaterial changes. F1574creep—a transient stress-strain condition in which the strainincreases as the stress remains constant. (This condition isapproached in flat-face gasketing joints in which the boltundergoes a high elongation relative to any creep that mighttake place in the gasket.) F38creep relaxation—a transient stress-strain condition in whichthe strain increases concurrently with the decay of stress.(This is the most common condition existing in flat-facegasketing assemblies in which the bolt exhibits a relativelylarge amount of elongation.) Strain is related to materialcreep under the flange and stress is related to boltstretch/elongation. F38cross-sectional area—the area of a gasket specimen defined asthe width times the thickness.crush—maximum load capability of a gasket material has beenexceeded by excessive external force, causing permanentdeformation of the material matrix. This permanent defor-mation is normally exhibited as splits in the gasket materialupon disassembly of the joint.deflection—gasket material deformation in the “thicknessdirection” caused by the application of stress. F1276deformation—the percentage by which a gasket material isdeformed under stress or after the application of stress.F1574density—the mass per unit volume for a given gasket materialmeasured under defined conditions. F1315description/line call out—an alphanumeric term used todefine the composition, method of manufacture, mechanicalproperties, and physical properties of a gasket material.F104, F868disintegration—the process by which a gasket material breaksup into components or fragments after exposure to a givenfluid and/or environment. F148durability—the resistance to disintegration of a gasket mate-rial after exposure to a given fluid and/or environment. F1481These definitions are under the jurisdiction of ASTM Committee F03 onGaskets and are the direct responsibility of Subcommittee F03.94 on Terminology.Current edition approved July 1, 2013. Published August 2013. Originallyapproved in 1970. Last previous edition approved in 2012 as F118 – 04 (2012).DOI: 10.1520/F0118-13.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1extrusion—the measurable amount of permanent movement ofa gasket material to unconstrained areas (that is, open flangeedges) when excessive external forces are applied to all orpart of the gasket matrix.flange—the members of a gasketed joint that compress thegasket.flange distortion—deviation of a contact surface from aperfect plane.flange misalignment—an off-set between gasket flanges thatcan induce additional external “per unit area” forces upon agasket due to less than design intent area under compression.flanged joint—see gasketed joint, which is a preferred term.flat faced joint—a joint or flange with no raised contactsurface.flexibility—the ratio of mandrel size a gasket material can bebent 180 degrees around without cracking to the thickness ofsaid gasket material. F147fluid—a gas or liquid used for immersion and sealabilitytesting of gasket materials. F37, F146gasket—a material that may be clamped between faces andacts as a static or dynamic seal. Gaskets are cut, formed, ormolded into the desired configuration. They may consist ofany of the following constructions:(a) One or more plies of a sheet material;(b) Composites of dissimilar materials; and(c) Materials applied as a bead or other form to one or bothmating faces prior to assembly.gasketed joint—the collective total of all members used toeffect a gasketed seal between two or more separate items.leak—the passage of matter through interfacial openings orpassageways, or both, in or around the gasket.leak rate—the rate at which fluid escapes from a gasketedjoint.leakage—the amount of loss or escape of any media (fluid orgas) intended to be contained by the gasketed system.linear dimensional stability—the degree to which a gasketmaterial maintains its original size in the x-y plane afterexposure to specific conditions.maintenance factor, m—the factor that provides the addi-tional preload capability in the flange fasteners to maintainsealing pressure on a gasket after internal pressure is appliedto the joint.manometer—a device used to measure pressure in a closedsystem. It may be used to measure leakage of fluids throughgasketed joints.peak load—the highest stress a gasket material can resistbefore tensile failure. F152platens—rigid circular test plates drilled with a hole for thecenter bolt, used to compress the test specimen underspecified load.recovery—in compressibility/recovery testing of gasketmaterials, the difference between the specimen recoveredthickness and thickness under total load, divided by thedifference between the thickness under preload and thicknessunder total load, expressed as a percent.relaxometer—assembly used in creep relaxation tests whichconsists of two platens, special drilled and calibrated bolt,washer and nut. F38, F1276resiliency—in compressibility/recovery testing of gasketmaterials, the difference between the specimen recoveredthickness and thickness under total load, divided by thethickness under total load, expressed as a percent.sealability—the measure of leak rate a gasket material has fora given gasket geometry, fluid with applied internal pressure,and applied flange pressure. Typically reported as a volumeor mass of fluid loss for a given time period and used asmeans of comparison. F37strain—the deformation of a gasket specimen under the actionof applied force or stress.stress—The force per unit area applied to a gasket material.stress relaxation—a transient stress-strain condition in whichthe stress decays as the strain remains constant. (Thiscondition is encountered in grooved-face gasketing joints inwhich metal-to-metal contact occurs. This condition is alsoapproached in flat-face gasketing joints when the bolt ispractically infinitely rigid.)tensile strength—the maximum tensile stress applied duringstretching a specimen to rupture. F152tensile stress—the applied force per unit on original cross-sectional area of a specimen. F152torque bolt—a calibrated bolt (also called a drilled and pinnedbolt) made of a defined alloy that contains a pin mechanismwhich allows the user to measure bolt stretch. The bolt ispart of a relaxometer. F38, F1276yield factor (minimum design seating stress, y)—the factorthat represents the pressure in megapascals (or pounds-forceper square inch) over the contact area of the gasket that isrequired to provide a sealed joint, with no internal pressurein the joint.F118 − 132ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. 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