ASTM_F_2523_-_13.pdf

Designation:F252313Standard Practice forBlowout Resistance of Room-Temperature VulcanizedElastomers1This standard is issued under the fixed designation F2523;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice provides a means to determine the blowoutresistance of a room-temperature vulcanized elastomer system(RTV)using a standard fixture.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D907 Terminology of AdhesivesD1566 Terminology Relating to RubberF2468 Classification for Specifying Silicone Adhesives andSealants for Transportation Applications2.2 SAE Standard:SAE J1199 Mechanical and Material Requirements for Met-ric Externally Threaded Steel Fasteners33.Terminology3.1 DefinitionsSome terms in this practice are defined inTerminologies D907 and D1566.3.2 Definitions of Terms Specific to This Standard:3.2.1 blowout,ndisruption of the uncured RTV integrityin a joint from system pressurization resulting in sudden loss ofpressure.3.2.2 Tjoint,ninterface created in a sealing surfacewhere three structural components meet.3.2.2.1 DiscussionThis interface may exist as a small gaprequiring a material such as room-temperature vulcanizedelastomer(RTV)to seal.3.3 Acronyms:3.3.1 RTVroom-temperature vulcanized elastomer4.Summary of Practice4.1 Condensation cures RTVs as a one-component systemcure when exposed to moisture in the ambient air or astwo-component systems when those components are mixedtogether.RTVs are often used to seal joints where three flangesmeet(T joints)such as an automotive engines front cover,engine block,and oil pan.Because of machining and assemblytolerance variations,these T joints may have a slight misalign-ment or gap.We also find gaps in the half-round area of the oilpan to block and in the valley between the intake manifold andblock on certain V-engines as a result of manufacturingtolerances.The RTV is used to seal in fluids.In some assemblyline applications,soon after the RTV is applied and the flangesfastened together,the system is subjected to an air decay test ata designated pressure.This test is used to determine an RTVscapability to withstand loss of integrity at this designatedpressure.4.2 When using this practice,one must first determine themaximum gap based on stack tolerances of the system.Atwo-piece round fixture uses the top portion to mirror thesystem gap(default gap is 1 mm),while the bottom halfprovides the mating flange and the connection for the pressureinput.The gap is machined into the top half of the fixture in a“pie slice”60 angle.A continuous bead of RTV is applied tothe entire bottom portion of the fixture,the top half is carefullyattached,and the fixture is pressurized to the prescribed limitsand held for a specified time period.If the RTV is not capableof sealing at the pressure applied,a sudden loss of pressure willoccur.5.Significance and Use5.1 This practice may be used to determine the viability ofan RTV sealant to withstand pressure leak testing before cureat maximum gap conditions of a system.This practice may be1This practice is under the jurisdiction ofASTM Committee F03 on Gaskets andis the direct responsibility of Subcommittee F03.70 on Formed in Place Gaskets.Current edition approved July 1,2013.Published August 2013.Originallyapproved in 2005.Last previous edition approved in 2013 as F2523 07(2013).DOI:10.1520/F2523-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from Society of Automotive Engineers(SAE),400 CommonwealthDr.,Warrendale,PA 15096-0001.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 used to indicate an RTVs acceptability to undergo an assemblyline leak check without causing a leak path due to materialblow out.6.Apparatus46.1 FixtureAluminum,see Fig.1.6.1.1 Aluminum casting,forging,or bar stock with 60Brinell hardness,minimum.6.1.2 Surface finish shall be in the range of 0.7 to 3.2 m Ra.6.1.3 Top half of fixture shall have a machined cutout to thedesired gap depth(1.0 6 0.025 mm default gap),per Fig.1.The gap and flange width are critical dimensions and should becontrolled to a tight tolerance(62.5%is recommended).Allother dimensions