ASTM C1249-2018 Standard Guide for Secondary Seal for Sealed Insulating Glass Units for Structural Sealant Glazing Applications.pdf

1、Designation: C1249 18Standard 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 rev

2、ision, 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 i

3、nsulating 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 si

4、ded 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 (Fi

5、g. 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

6、 all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 The committee with jurisdiction for this

7、 standard is notaware of any comparable standard guides published by otherorganizations.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,

8、 Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.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 Terminol

9、ogy 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 TensileAdhesion Prop-erties of Structural

10、 SealantsC1184 Specification for Structural Silicone SealantsC1369 Specification for Secondary Edge Sealants for Struc-turally Glazed Insulating Glass UnitsE631 Terminology of Building ConstructionsE773 Test Method for Accelerated Weathering of SealedInsulating Glass Units (Withdrawn 2010)3E2188 Tes

11、t Method for Insulating Glass Unit PerformanceE2189 Test Method for Testing Resistance to Fogging inInsulating Glass UnitsE2190 Specification for Insulating Glass Unit Performanceand Evaluation2.2 IGMA Standards:4TR-1000-75(91) Voluntary Test Methods for Chemical Ef-fects of Glazing Compounds on Ela

12、stomeric Edge Seals1This 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, 2018. Published July 2010. Originally approvedin 1993. Last prev

13、ious edition approved in 2006 as C124906a. DOI: 10.1520/C1249-18.2For 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 webs

14、ite.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Insulating Glass Manufacturers Alliance (IGMA), 1500 BankSt., Ottawa, ON K1H 1B8, Canada, https:/www.igmaonline.org/.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho

15、cken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organi

16、zation Technical Barriers to Trade (TBT) Committee.1TM-4000 Insulating Glass Manufacturing Quality Proce-dures2.3 NFRC Document:5NFRC 706 Requirements for Participating Insulating GlassCertification Programs3. Terminology3.1 Definitions:3.1.1 Refer to Terminology C717 for definitions of thefollowing

17、 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.Refe

18、r 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).3.2.1.1 DiscussionThe desiccant maintains a low rel

19、ativehumidity 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 t

20、he 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 appropriatedistance between two lites of glass in sealed insulating glass(see

21、Fig. 1).3.2.4.1 DiscussionAs a component of the edge sealsystem, the spacer also resists vapor migration into sealedinsulating glass and provides a container for a desiccant.3.2.5 structural seala joint seal of which the sealantstructurally adheres an IG unit to a metal framing system (seeFig. 2).3.

22、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:3.3.1 A = area, m2(in.2).3.3.2 Cs= sealant contact width, shear, mm (in.).3.3.3 Ct= sealant contact width, tension,

23、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 length, m (ft).3.3.10 M = mass per unit area, N/m2(lb/ft2).3.3.11 P = applied load, Pa

24、 (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 manufacturer, and designprofessional, among others.4.2 This guide provides informati

25、on 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 components,durability, and quality assurance (QA).5. Insulating Glass Unit5.1 Insulating

26、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).6This type of IG unit is referred to commonly as a dual-seal unitin that it has separate primary and secondary seals. A single-seal IG

27、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 glass have been used in thefabrication of IG units, including monolithic, laminated,temp

28、ered, heat-strengthened, tinted, heat-absorbing, lightreducing, patterned, and wired.Almost all glass is produced bythe float manufacturing process, in which the glass ribbon thatemerges from the furnace is floated on a bath of molten tin,allowing gravity to produce essentially flat parallel surface

29、s.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 both metallic or metallic5Available from National Fenestration Rating Council (NFRC), 6305

30、Ivy Ln.,Suite 140, Greenbelt, MD 20770, https:/www.nfrccommunity.org/page/ProgramDocs.6The boldface numbers in parentheses refer to the list of references at the end ofthis guide.FIG. 1 Sealed IG Edge Seal: Basic ComponentsC1249 182oxide materials and in some cases are in multi-layers, depos-ited on

31、to or into a glass surface. 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-mi

32、ttance of the glass. In 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 coa

33、tings pro-vide a reduction 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 fro

34、m a variety of mate-rials including metals, rigid plastics and foam cured sealant,and combinations of these materials. They are available innumerous profiles, depending on the application. Metals typi-cally used are aluminum, both mill finish and anodized,galvanized steel, and stainless steel. Rigid

35、 plastic and foamspacers are commonly used with a thin metallic vapor barrieron the backside. Material selection and geometric design canreduce the heat transfer at the edge of the IG unit. The spacerestablishes the size of the sealed space, provides surfaces forinstallation of the primary sealant,

36、is a reservoir for desiccant,and forms the third surface of the cavity created at the edge ofthe glass lites for installation of the secondary sealant.5.4 DesiccantThese substances are hydrophilic crystallinematerials that are installed into the hollow of the spacer,usually on at least two sides of

37、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 low relative humidity inthe sealed space for the

38、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 acts as a barrier to the permeation of inertgas

39、es (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 materials. The primary sealant must also have suff

40、icientmovement 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 to the structural function of transferring latera

41、l 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 glass, whichthen transfers the load to the structura

42、l 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 must maintain ad-equate adhesion to the glass lite

43、s 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 or adhesive or cohesivefailure of the secondary

44、 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. For SSG systems, only IG units with adual-seal (

45、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 hexafloride. Air isnormally used if conventional

46、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, the IG unit edge seal systemmust be capable of

47、retaining a substantial percent of the gas forFIG. 2 Typical A-Side SSG System Mullion: Horizontal Section (Vertical Joint)C1249 183the 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 Tube

48、Abreather tube is a small tube or holethat 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 atmosph

49、eric pressure at the installation site. 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 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 press