1、Designation: C1249 06a (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,
2、 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 conv
3、entionally 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,
4、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
5、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
6、 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 t
7、his 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 ElastomericSealantsC717 Terminology of Building Seals
8、and SealantsC794 Test Method for Adhesion-in-Peel of ElastomericJoint SealantsC1087 Test Method for Determining Compatibility ofLiquid-Applied Sealants with Accessories Used in Struc-tural Glazing SystemsC1135 Test Method for Determining Tensile AdhesionProperties of Structural SealantsC1184 Specifi
9、cation for Structural Silicone SealantsE631 Terminology of Building ConstructionsE773 Test Method for Accelerated Weathering of SealedInsulating Glass Units3E774 Specification for the Classification of the Durability ofSealed Insulating Glass Units3E2188 Test Method for Insulating Glass Unit Perform
10、anceE2189 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 ofGlazing Compounds on Elastomeric Edge Seals43. Terminology3.1 Definitions:1This
11、guide is under the jurisdiction ofASTM Committee C24 on Building Sealsand Sealants and is the direct responsibility of Subcommittee C24.10 on Specifi-cations, Guides and Practices.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 1993. Last previous edition approved i
12、n 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.3Withdrawn. The
13、 last approved version of this historical standard is referencedon www.astm.org.4Available from IGMA, 111 E. Wacker Dr., Ste. 600, Chicago, IL 60601.FIG. 1 Sealed IG Edge Seal: Basic Components1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
14、 States.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, glaz-ing, joint, lite, modulus, non-sag sealant, seal, sealant, sealantbacking, setting block, shelf-life, silicone seal
15、ant, spacer,structural sealant, substrate, tooling, and working life. Refer toTerminology E631 for the definition of sealed insulating glassas 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, o
16、r both (see Fig. 1).3.2.1.1 DiscussionThe desiccant maintains a low relativehumidity in sealed insulating glass.3.2.2 primary sealAjoint 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
17、 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 appropri
18、atedistance between two lites of glass in sealed insulating glass(see Fig. 1).3.2.4.1 DiscussionAs a component of the edge seal sys-tem, the spacer also resists vapor migration into sealed insu-lating glass and provides a container for a desiccant.3.2.5 structural seala joint seal of which the seala
19、ntstructurally adheres an IG unit to a metal framing system (seeFig. 2).3.2.5.1 DiscussionThe structural seal transfers appliedloads to the framing system as well as accommodates differ-ential movements between the IG unit and the framing system.3.3 Symbols:Symbols:3.3.1 A = area, m2(in.2).3.3.2 Cs=
20、 sealant contact width, shear, mm (in.).3.3.3 Ct= sealant contact width, tension, mm (in.).3.3.4 D = design factor, dimensionless.3.3.5 Fs= allowable shear stress, Pa (psi).3.3.6 Ft= allowable tensile stress, Pa (psi).3.3.7 Fy= yield stress, Pa (psi).3.3.8 H = height, m (ft).3.3.9 L = perimeter leng
21、th, m (ft).3.3.10 M = mass per unit area, N/m2(lb/ft2).3.3.11 P = applied load, Pa (lbf/ft2).3.3.12 W = width, m (ft).4. Significance and Use4.1 It should be realized that the design of an IG unit edgeseal for use in SSG systems is a collaborative effort of at leastthe IG unit fabricator, sealant ma
22、nufacturer, and design pro-fessional, among others.4.2 This guide provides information on silicone sealants thatare used for the secondary seal of IG units that are glazed intoSSG systems.4.3 Information is also provided on the other major compo-nents of the IG unit edge seal, compatibility of compo
23、nents,durability, and quality assurance (QA).5. Insulating Glass Unit5.1 Insulating Glass Unit ComponentsThe edge seal of anSSG system IG unit consists of the two lites of glass, spacer,desiccant, primary sealant, and secondary sealant (Fig. 1) (1).5This type of IG unit is referred to commonly as a
24、dual-seal unitin that it has separate primary and secondary seals. A single-seal IG unit is inappropriate at this time for SSG systems andshould not be used. The following sections describe thecomponents of a dual-seal IG unit briefly.5.2 Glass and Architectural Coatings:5.2.1 GlassAll types of glas
25、s have been used in thefabrication of IG units, including monolithic, laminated, tem-pered, heat-strengthened, tinted, heat-absorbing, light reduc-ing, patterned, and wired. Almost all glass is produced by thefloat manufacturing process, in which the glass ribbon thatemerges from the furnace is floa
26、ted on a bath of molten tin,allowing gravity to produce essentially flat parallel surfaces.5.2.2 Architectural CoatingsThese coatings, which areapplied to the surface of the glass prior to IG unit fabrication,are generally grouped into one of two categories: low-emissivity or reflective. They are bo
27、th metallic or metallic5The boldface numbers in parentheses refer to the list of references at the end ofthis guide.FIG. 2 Typical A-Side SSG System Mullion: Horizontal Section (Vertical Joint)C1249 06a (2010)2oxide materials and in some cases are in multi-layers, depos-ited onto or into a glass sur
28、face. The coatings are depositedprimarily by two methods: magnetic sputtering onto the glasssurface and pyrolitic deposition into the glass surface. Low-emissivity coatings are visually transparent and reflect long-wave infrared radiation, thereby improving the thermal trans-mittance of the glass. I
29、n general, they also decrease but to alesser extent than reflective coatings, visible light transmission,and transmitted solar radiant energy. Depending on lightingconditions, reflective coatings are generally considerably lesstransparent than low-emissivity coatings. These coatings pro-vide a reduc
30、tion in transmitted solar radiant energy, conductiveheat energy, and visible light into the building interior. Ceramicenamel, silicone, and pressure-sensitive vinyl and polyesterfilm are applied to the surface of glass to make spandrel glass.5.3 SpacerSpacers are fabricated primarily from roll-forme
31、d hollow metal shapes and are available in numerousprofiles, depending on the application. Metals typically usedare aluminum, both mill finish and anodized, galvanized steel,and stainless steel, with aluminum used predominately. Thespacer establishes the size of the sealed space, providessurfaces fo
32、r installation of the primary sealant, is hollow fordesiccant installation, and forms the third surface of the cavitycreated at the edge of the glass lites for installation of thesecondary sealant.5.4 DesiccantThese substances are hydrophilic crystal-line materials that are installed into the hollow
33、 of the spacer,usually on at least two sides of the IG unit. Commonly useddesiccants are molecular sieves or a blend of silica gel withmolecular sieves. Their purpose is to adsorb residual water andsolvent vapor in the sealed space immediately after fabricationof the IG units. They also maintain a l
34、ow relative humidity inthe sealed space for the life of the IG unit by absorbinginfiltrating moisture vapor.5.5 Primary SealantThis sealant provides a high level ofmoisture vapor migration resistance and controls and mini-mizes gas and solvent migration into the IG unit sealed space.The sealant also
35、 acts as a barrier to the permeation of inertgases (for example, argon) when these gases are used in thesealed space of the IG unit. The sealant is designed to fill thespace between the sides of the spacer and the faces of the twoglass lites and to develop adequate adhesion to the surfaces ofboth ma
36、terials. The primary sealant must also have sufficientmovement capability to not fail due to limited differentialmovement that may occur between the spacer and the glasslites. Polyisobutylene-based materials have been found to bevery suitable for this purpose. The primary sealant contributeslittle t
37、o the structural function of transferring lateral loads andholding the IG unit edge assembly together. These functionsare fulfilled by the secondary sealant.5.6 Secondary Sealant:5.6.1 This sealant transfers negative lateral loads, occurringon the exterior lite of glass, to the interior lite of glas
38、s, whichthen transfers the load to the structural sealant that adheres theIG unit to the metal framing system. It also functions as theadhesive that unites the two glass lites and spacer together asa unit and prevents excessive movement from occurring in theprimary seal (2). The secondary sealant mu
39、st maintain ad-equate adhesion to the glass lites and spacer and also maintainother performance properties, such as strength and flexibilityafter prolonged environmental exposure. Failure of the second-ary seal to do so could result in excessive movement in theprimary seal and fogging of the IG unit
40、 or adhesive or cohesivefailure of the secondary seal and catastrophic failure of the IGunit.5.6.2 Four generic classes of sealants are used presently fora conventional IG unit edge seal system (non-structural seal-ant). These sealants are polysulfides, polyurethanes, hot-meltbutyls, and silicones.
41、For SSG systems, only IG units with adual-seal (polyisobutylene primary seal and silicone secondaryseal) have the required durability for the application and are theonly sealants permitted for SSG systems.5.7 Enclosed GasThe IG unit sealed space encloses a gassuch as air, argon, krypton, or sulfur h
42、exafloride. Air isnormally used if conventional thermal resistance properties arerequired. Argon and krypton are used to increase the IG unitthermal resistance. Sulfur hexafloride is used in applications inwhich increased resistance to sound transmission is necessary.When using gases other than air,
43、 the IG unit edge seal systemmust be capable of retaining a substantial percent of the gas forthe life of the IG unit; otherwise, thermal or sound transmissionperformance will decrease to an unacceptable level.5.8 Breather and Capillary Tubes:5.8.1 Breather TubeAbreather tube is a small tube or hole
44、that is factory-placed through the spacer of the IG unit toaccommodate an increase in sealed air space pressure when anIG unit is shipped to a higher elevation than where fabricated.The breather tube allows the sealed air space pressure toequalize to the atmospheric pressure at the installation site
45、. Thebreather tube is sealed prior to the IG unit installation. Specialsealed space gases (see 5.7) cannot be used in IG units thathave breather tubes.5.8.2 Capillary TubeA capillary tube is a very thin boretube of specific length and inside diameter that is factory-placed through the spacer of the
46、IG unit. A capillary tubefulfills the same function as a breather tube and, in addition, isleft open during transportation to permit the sealed space of theIG unit to continue to pressure equalize with fluctuatingambient air pressure. Capillary tubes should be sealed with ahigh performance sealant s
47、pecified by the IG fabricator at thefinal destination immediately before installation. Special sealedspace gases (see 5.7) cannot be used in IG units that havecapillary tubes.SECONDARY SEALANT DESIGN CONSIDERATIONS6. Structural Properties6.1 General:6.1.1 The design of an IG unit edge seal parallels
48、 themethodology used for the design of the SSG system structuraljoint that adheres an IG unit to a framing system. SSG systemstructural sealants must meet the requirements of SpecificationC1184. Presently, there is no comparable specification forsealants used for the secondary sealant of IG units; h
49、owever,sealants should meet the requirements of Specification C1184(as a minimum) in the absence of another applicable specifi-cation.C1249 06a (2010)36.1.2 The following sections provide the design profes-sional with information on the design of the IG unit edge sealsecondary sealant regarding the following: allowable tensilestrength; modulus properties; appropriate design factors; anddesign of the secondary sealant for the effects of shear stress,tensile stress, and combined stresses.6.2 Sealant Yield StressThe minimum sealant yield stress(Fu) (or tensile adhes
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