ASTM_C_1249_-_06a_2010.pdf

Designation:C124906a(Reapproved 2010)Standard Guide forSecondary Seal for Sealed Insulating Glass Units forStructural Sealant Glazing Applications1This standard is issued under the fixed designation C1249;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 guide covers design and fabrication considerationsfor the edge seal of conventionally sealed insulating glassunits,herein referred to as IG units.The IG units described areused in structural silicone sealant glazing systems,hereinreferred to as SSG systems.SSG systems typically are eithertwo or four sided,glazed with a structural sealant.Otherconditions such as one,three,five,six sided may be used.1.2 This guides does not cover the IG units of other thanconventional edge seal design(Fig.1);however,the informa-tion contained herein may be of benefit to the designers of suchIG units.1.3 In an SSG system,IG units are retained to a metalframing system by a structural seal(Fig.2).The size and shapeof that seal,as well as numerous other SSG system designconsiderations,are not addressed in this guide.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety problems,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.1.6 The committee with jurisdiction for this standard is notaware of any comparable standard guides published by otherorganizations.2.Referenced Documents2.1 ASTM Standards:2C639 Test Method for Rheological(Flow)Properties ofElastomeric SealantsC679 Test Method for Tack-Free Time of Elastomeric Seal-antsC717 Terminology of Building Seals and SealantsC794 Test Method forAdhesion-in-Peel of Elastomeric JointSealantsC1087 Test Method for Determining Compatibility ofLiquid-Applied Sealants with Accessories Used in Struc-tural Glazing SystemsC1135 Test Method for Determining Tensile Adhesion Prop-erties of Structural SealantsC1184 Specification for Structural Silicone SealantsE631 Terminology of Building ConstructionsE773 Test Method for Accelerated Weathering of SealedInsulating Glass Units(Withdrawn 2010)3E774 Specification for the Classification of the Durability ofSealed Insulating Glass Units(Withdrawn 2006)3E2188 Test Method for Insulating Glass Unit PerformanceE2189 Test Method for Testing Resistance to Fogging inInsulating Glass UnitsE2190 Specification for Insulating Glass Unit Performanceand Evaluation2.2 Other Standards:Igma 73-8-2B Test Methods for Chemical Effects of Glaz-ing Compounds on Elastomeric Edge Seals43.Terminology3.1 Definitions:3.1.1 Refer to Terminology C717 for definitions of thefollowing terms used in this guide:adhesive failure,bead,cohesive failure,compatibility,cure,elongation,gasket,glazing,joint,lite,modulus,non-sag sealant,seal,sealant,sealant backing,setting block,shelf-life,silicone sealant,spacer,structural sealant,substrate,tooling,and working life.Refer to Terminology E631 for the definition of sealed insu-lating glass as used in this guide.3.2 Definitions of Terms Specific to This Standard:3.2.1 desiccanta hygroscopic material that adsorbs wateror may adsorb solvent vapors,or both(see Fig.1).1This guide is under the jurisdiction ofASTM Committee C24 on Building Sealsand Sealants and is the direct responsibility of Subcommittee C24.10 onSpecifications,Guides and Practices.Current edition approved June 1,2010.Published July 2010.Originally approvedin 1993.Last previous edition approved in 2006 as C124906a.DOI:10.1520/C1249-06AR10.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from IGMA,111 E.Wacker Dr.,Ste.600,Chicago,IL 60601.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.1.1 DiscussionThe desiccant maintains a low relativehumidity in sealed insulating glass.3.2.2 primary sealA joint seal of which the sealant resistsmoisture vapor permeation into the desiccated space of sealedinsulating glass(see Fig.1).3.2.2.1 DiscussionIt also resists inert gas permeation(forexample,argon)from the IG unit sealed space if the intent is touse an inert gas.3.2.3 secondary seala joint seal of which the sealantstructurally unites the two glass lites and spacer of sealedinsulating glass(see Fig.1).3.2.4 spacera fabricated shape that creates an appropriatedistan