1、Designation: E1773 10Standard Practice forSealing Rigid Wall Tactical Shelters with Polysulfide BasedSealants1This standard is issued under the fixed designation E1773; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers the procedures for
3、 sealing rigidwall tactical shelters. It outlines the techniques for the storage,mixing, handling, and application of polysulfide based seal-ants.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are
4、provided for information onlyand are not considered standard.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-
5、bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D907 Terminology of AdhesivesE1749 Terminology Relating to Rigid Wall RelocatableShelters2.2 Society of Automotive Engineers (SAE) Specification:3SAE-AMS-S-8802 Sealing Compound, Temperature-Resistant, Integral
6、Fuel Tanka and Fuel Cell Cavities,High AdhesionSAE-AMS-3819 Cleaning Cloths3. Terminology3.1 DefinitionsSee Terminology E1749 for definitions ofgeneral terms used in this practice.3.2 Definitions of Terms Specific to This Standard:3.2.1 acceleratorused by sealant formulators to denote aningredient i
7、ncluded in the formulation to accelerate the rate ofcure. It is also used separately in a mixture to accelerate surfacecuring only of applied polysulfide sealant, that is, tack free timeaccelerator.3.2.2 adhesionThe state in which two surfaces are heldtogether by interphase forces. D9073.2.3 applica
8、tion time (sealants)the time available forsealant application after mixing or time available after thawinga premixed and frozen cartridge of sealant.3.2.3.1 DiscussionAcceptability limits for Class B ex-trudable sealants are expressed in terms of the extrusion rate ofa sealant froma6floz(180 mL) car
9、tridge through a nozzlewith a 0.125 in. (3.2 mm) diameter orifice, using air pressure of90 6 5 psi (620 6 34 kPa) in a pneumatic sealant gun. Theextrusion rate is expressed in grams per minute or on cc perminute. A minimum extrusion rate after the stated applicationtime is given as the acceptable li
10、mit. Sealant applied after theapplication time is exceeded tends not to wet the surface welland thus not to form a good bond. This term should not be usedinterchangeably with work life.3.2.4 assembly timethe amount of time available after atwo-part sealant is mixed, before the faying surfaces, to wh
11、ichsealant is applied, shall be assembled and the sealant squeezedout.3.2.4.1 DiscussionIf the assembly time is exceeded, thecure will have progressed too far to permit most of the sealantto be squeezed out for the desired surface to surface contact.The term assembly time is used in reference to fay
12、ing-surfacesealants. Also called work life and open time.3.2.5 base compoundthe major component of a two-partcuring sealant that contains the polysulfide polymer.3.2.6 bridgingsee Terminology E1749.3.2.7 cartridgea plastic container which contains an inte-gral plunger.3.2.7.1 DiscussionThe cartridge
13、 is used to contain either afrozen quantity of premixed base compound and curing com-pound or simply the base compound in unmixed injection kits.3.2.8 cohesion strength (sealant)the internal forces hold-ing a cured sealant together.1This practice is under the jurisdiction of ASTM Committee E06 on Pe
14、rfor-mance of Buildings and is the direct responsibility of Subcommittee E06.53 onMaterials and Processes for Durable Rigidwall Relocatable Structures.Current edition approved Nov. 1, 2010. Published December 2010. Originallyapproved in 1995. Last previous edition approved in 2005 as E1773 05. DOI:1
15、0.1520/E1773-10.2For 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 SAE International (SAE), 400
16、Commonwealth Dr., Warrendale,PA 15096-0001, http:/www.sae.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.9 contaminantany foreign substance that degrades theperformance of the sealant.3.2.10 cure ratethe rate at which a seal
17、ant polymerizes orcrosslinks (that is, solidifies), a measure of which is thehardness of a sealant at a specified cure time.3.2.11 cure time (sealants)the time required for a sealantto polymerize and develop its full physical/mechanical prop-erties.3.2.11.1 DiscussionIn practice, however, it is the
18、timerequired to reach a designated hardness.3.2.12 curing compoundthe crosslinking agent for thebase compound.3.2.13 hardnesssee Shore A hardness and REX Hard-ness in Terminology E1749.3.2.14 interference seala seal produced between a givendiameter mechanical fastener and a smaller diameter hole in
19、amember into which it is inserted.3.2.14.1 DiscussionAn interference seal is also producedwhen a fastener shank is expanded by the installation process.3.2.15 primary seala seal which, in combination with thestructure and optional brush coat or secondary seal, forms acontinuous, durable seal in the
20、sealing plane and requires noadditional seals.3.2.16 self-sealing fastenera fastener that provides a tightseal without the need for sealant materials or the use of amechanical seal.3.2.16.1 DiscussionAn interference fit fastener is an ex-ample.3.2.17 tack free timethe time required for a curing seal
21、antto lose its surface tackiness to polyethylene.3.2.17.1 DiscussionRefer to SAE-AMS-S-8802.3.2.18 tooled filleta fillet formed by working an appliedbead of sealant to a feathered edge using a shaped tool.3.2.18.1 DiscussionThe goal is to ensure good surfacecontact at the feathered edges, to elimina
22、te voids, trapped airand re-entrant edges, and to produce a contour of the correctthickness and shape over the area being sealed.3.2.19 two-component sealant injection kita kit designedfor the mixing and application of a two-part sealant. The kitconsists of a plastic (usually polyethylene) cartridge
23、 filled withbase compound, a hollow dasher rod containing curing com-pound, and a plunger. The dasher rod extends into one end ofthe cartridge; at the end of the dasher rod inside the cartridge,a multi-armed agitator is attached. The plunger caps the otherend of the cartridge.3.2.19.1 DiscussionTo u
24、se, a ram rod is inserted into thedasher rod and the curing compound is forced into the basecompound. The dasher rod is then pulled back and forth at aspecified rate with periodic rotation to add to the efficiency ofthe agitator. When the sealant is mixed thoroughly, the dasherrod is unscrewed from
25、the agitator and removed. A nozzle isscrewed onto the cartridge and the unit inserted into a sealantgun. Sealant is dispensed as the plunger is pushed further intothe cartridge.3.2.20 wet installed fastenersfasteners that are coated onthe shank and under the head with a curing-type sealant toprovide
26、 a corrosion barrier and a secondary seal.4. Significance and Use4.1 This recommended practice is intended to provideinformation on the storage, mixing, handling, and applicationof polysulfide based sealants. Tooling and equipment require-ments for the satisfactory application of the sealants to joi
27、nts intactical shelters are also provided.5. Hazards5.1 MaterialsThe precautions outlined in the manufactur-ers material safety data sheets (MSDS) for the materials beingused shall become a part of this practice.5.2 Work Place:5.2.1 All lights and other electrical equipment used for thesealant appli
28、cation within an enclosed shelter shall be explo-sion proof. Extension cords shall be long enough to makeelectrical connections outside the shelter.5.2.2 When use of compressed air is required, proper safetyequipment shall be provided and used.6. Storage6.1 Premixed and Frozen SealantSealants that a
29、re sup-plied premixed and frozen shall be stored in a cold box or aroom maintained at 40 6 5F (40 6 2.8C) or within 65C(2.8F) of the manufacturers recommended storage tempera-ture.6.2 Two-Component Sealant KitsTwo-component seal-ants supplied as either injection kits or bulk sealant kits shall besto
30、red in areas maintained at a temperature not to exceed 80F(27C).7. Labeling7.1 Sealant containers shall have attached labels whichclearly identify the product, manufacturer, matched base andcuring compounds (if applicable), batch and lot numbers, dateof manufacture, recommended mix ratio (if applica
31、ble), andexpiration date under specified storage conditions.8. Material Handling8.1 Premixed and FrozenSealants are supplied premixedand frozen, used prior to the manufacturers expiration date onthe label, and shall be ready for immediate use followingthawing of the contents. With the addition of a
32、nozzle, thematerial is dispensed directly from the cartridge.8.2 Two-Component Sealant Injection KitsSealants sup-plied in this form shall be mixed according to the manufactur-ers instructions and used before the expiration date providedon the label and within the application time determined for tha
33、tsealant.8.3 Bulk SealantTwo-part sealants are supplied in a widerange of kit sizes from12 pt to 50-gal drums plus 5-gal pail ofcuring compound. In every case there is a small percentage ofextra curing compound included, ranging from 2 to 10 % tocompensate for losses in the transfer of the curing co
34、mpound.Although kit sizes are generally quoted in terms of volume, thebase and curing compound are matched on basis of weightratio. Both weight and volume ratio are usually included on thelabel.E1773 1028.3.1 Mixing:8.3.1.1 Hand MixingKits under 5 gal are packaged suchthat the base compound containe
35、r will permit the addition andmixing of the curing compound. Mix the entire kit at one timeand use all the curing compound. By mixing and using theentire kit at once, the user is assured that the correct amountshave been used and the resultant sealant properties will bethose expected. Some of the pi
36、tfalls of attempting to use partialkits include: (1) the possible use of incorrect ratio; (2) incorrectweighing; (3) failure to thoroughly stir the curing compound inthe container before removing the desired quantity; (4) incom-plete transfer of base or curing compound, or both; and (5)compromising
37、the remaining material by failure to supply aninert atmosphere or failure to set the can lid completely.NOTE 1In all cases it is of paramount importance that the batch ofbase be catalyzed only with the batch of curing compound to which it wasmatched. (Batch number of batch of matched base and curing
38、 compoundshould be given on each label.) Hand mix thoroughly by folding thematerial over itself. Frequently scrape down the walls of the container toensure complete mixing. Avoid whipping the material as this willincorporate air into the mixture and result in void formation. High mixingspeeds may al
39、so cause excessive heat which will advance the cure of thesealant, shortening the application and assembly time. If the storage areatemperature is greatly different from normal (standard) temperature, thekits should be preconditioned to standard temperature 77F (25C); also,local humidity shall be on
40、 the order of 55 % RH if data sheet performanceis expected. If the surface to which the sealant is to be applied is decidedlydifferent from 77F (25C), the cure rate will vary accordingly. Forexample, a SAE-AMS-S-8802 B-2 system at 50 % RH will have a worklife of3hat60F (16C),2hat80F (27C), but only1
41、hat100F(37.8C). While if the temperature is held at 80F (27C), the work lifewill be3hat35%RH,2hat50%RH,andat65%RHthework life isonly 1 h.8.3.1.2 Machine MixingMeter/mix machines are usedwhen large quantities of mixed sealant are required. Separatepumps force base compound and curing compound through
42、 ametering system which measures the proper ratio of thecomponents. The two streams are then fed into a mixing headwhere a uniform mixture is produced. The sealant is thenusually dispensed into low density polyethylene cartridgesranging in size from 2.5 to 12 oz (74355 mL) for immediateuse or quick
43、frozen (see 8.5) for future use. The mixed sealantshould exhibit no visible streaks or evidence of entrapped air(bubbles or voids) during the dispensing operation. Whenusing meter mix machines the following steps should be madea part of the standard operating procedure:(a) Stir the 5-gal pail of cat
44、alyst thoroughly with amechanical agitator, being careful not to whip air into thecuring compound or excessively heat the material.(b) Scrape down the walls of the pail.(c) If the curing compound sits for 48 h after stirring, stiragain.(d) Start with clean lines and an empty meter/mix machineor purg
45、e the lines and machine with at least 2 gal of base andthe equivalent catalyst.(e) Calibrate a variable ratio machine frequently. (At thestart of each shift or the change of containers, or both).(f) If a static mix head is used, clean it if the flow ratedecreases substantially. Purging of the static
46、 mix head isessential if the material has set for one quarter of the applica-tion life.(g) Air pressure to the meter mix equipment should be ofsufficient volume as well as pressure.(h) Quality ControlA visual inspection should be con-ducted to ensure that no streaks or excessive air is incorporatedi
47、nto the mixed material.8.4 FreezingOnce the base compound and curing com-pound are mixed, the application time will decrease rapidly.Therefore, unless mixed sealants are to be used immediately,they should be quick frozen 40F (40C) or below. Thiscan be accomplished by placing the filled cartridges in
48、 a coldbath of methanol and dry ice for at least 30 min 100F(73.3C). Another approved method of quick freezing is toplace the freshly filled tube of sealant into a liquid nitrogenchamber for approximately 2 min. Place the frozen tubes in acold box or room at 40F (40C) or below at the manufac-turers
49、recommended storage temperature Frozen tubes ofpolysulfide sealants should not be kept for more than 1 month,or at the manufacturers prescribed shelf life, whichever islonger8.5 ThawingFrozen cartridges of mixed sealant may bethawed by three methods:(a) Normal temperature air, 8.5.1,(b) Enclosed heating bath, 8.5.2, and(c) Microwave oven, 8.5.3.In all methods of thawing, less application life per tube willbe available than in freshly mixed material. It is estimated thatapproximately 25 % of the
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