1、Designation: E 1773 05Standard Practice forSealing Rigid Wall Tactical Shelters with Polysulfide BasedSealants1This standard is issued under the fixed designation E 1773; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 recommended
3、 procedures forsealing rigid wall tactical shelters. It outlines the recommendedtechniques for the storage, mixing, handling, and application ofpolysulfide based sealants.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversi
4、ons to SI units that are 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 a
5、nd determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 907 Terminology of AdhesivesE 1749 Terminology Relating to Rigid Wall RelocatableShelters2.2 Military Specification:MIL-S-8802 Sealing Compound, Temperature-Resistant,Integral Fuel Tan
6、k and Fuel Cell Cavities, HighAdhesion32.3 Other Document:AMS 3819 Cleaning Cloths43. Terminology3.1 DefinitionsSee Terminology E 1749 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 aning
7、redient included 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. D 9073.2
8、.3 application 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(1
9、80 mL) cartridge 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 acc
10、eptable limit. 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 surfa
11、ces, to whichsealant 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 refere
12、nce to faying-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 E 1749.3.2.7 cartridgea plastic container which contains an inte-gral plunger.3.2.7.1 DiscussionTh
13、e cartridge 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 Committe
14、e E06 on Perfor-mance of Buildings and is the direct responsibility of Subcommittee E06.53 onMaterials and Processes for Durable Rigidwall Relocatable Structures.Current edition approved May 1, 2005. Published May 2005. Originallyapproved in 1995. Last previous edition approved in 2000 as E 1773 00.
15、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 Standardization Documents Order Desk, DODSSP,
16、 Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-50984Available from Society of Automotive Engineers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-0001.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.9 contaminanta
17、ny foreign substance that degrades theperformance of the sealant.3.2.10 cure ratethe rate at which a sealant 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
18、 and develop its full physical/mechanical prop-erties.3.2.11.1 DiscussionIn practice, however, it is the 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 E 1749.3.2.14 in
19、terference seala seal produced between a givendiameter mechanical fastener and a smaller diameter hole in 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 combin
20、ation with thestructure and optional brush coat or secondary seal, forms acontinuous, durable seal in the 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 Disc
21、ussionAn interference fit fastener is an ex-ample.3.2.17 tack free timethe time required for a curing sealantto lose its surface tackiness to polyethylene.3.2.17.1 DiscussionRefer to MIL-S-8802.3.2.18 tooled filleta fillet formed by working an appliedbead of sealant to a feathered edge using a shape
22、d tool.3.2.18.1 DiscussionThe goal is to ensure good surfacecontact at the feathered edges, to eliminate 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 mixin
23、g and application of a two-part sealant. The kitconsists of a plastic (usually polyethylene) cartridge 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 mu
24、lti-armed agitator is attached. The plunger caps the otherend of the cartridge.3.2.19.1 DiscussionTo use, 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
25、 the efficiency ofthe agitator. When the sealant is mixed thoroughly, the dasherrod is unscrewed from 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
26、fastenersfasteners that are coated onthe shank and under the head with a curing-type sealant toprovide 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
27、 sealants. Tooling and equipment require-ments for the satisfactory application of the sealants to joints 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
28、this practice.5.2 Work Place:5.2.1 All lights and other electrical equipment used for thesealant application 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, prop
29、er safetyequipment shall be provided and used.6. Storage6.1 Premixed and Frozen SealantSealants that are 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
30、Sealant KitsTwo-component seal-ants supplied as either injection kits or bulk sealant kits shall bestored 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 c
31、ompounds (if applicable), batch and lot numbers, dateof manufacture, recommended mix ratio (if applicable), 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
32、 label, and shall be ready for immediate use followingthawing of the contents. With the addition of a 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 u
33、sed before the expiration date providedon the label and within the application time determined for thatsealant.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 cur
34、ing compound included, ranging from 2 to 10 % tocompensate for losses in the transfer of the curing compound.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.8.3.
35、1 Mixing:E17730528.3.1.1 Hand MixingKits under 5 gal are packaged suchthat the base compound container 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 cor
36、rect amountshave been used and the resultant sealant properties will bethose expected. Some of the pitfalls 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
37、 desired quantity; (4) incom-plete transfer of base or curing compound, or both; and (5)compromising 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 t
38、he batch of curing compound to which it wasmatched. (Batch number of batch of matched base and curing 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 materia
39、l as this willincorporate air into the mixture and result in void formation. High mixingspeeds may also 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
40、, thekits should be preconditioned to standard temperature 77F (25C); also,local humidity shall be on 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,
41、 a MIL-S-8802 B-2 system at 50 % RH will have a work life of3 h at 60F (16C),2hat80F (27C), but only1hat100F (37.8C).While if the temperature is held at 80F (27C), the work life will be 3 hat35%RH,2hat50%RH,andat65%RHthework life is only 1 h.8.3.1.2 Machine MixingMeter/mix machines are usedwhen larg
42、e quantities of mixed sealant are required. Separatepumps force base compound and curing compound through 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 l
43、ow density polyethylene cartridgesranging in size from 2.5 to 12 oz (74355 mL) for immediateuse or quick 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 th
44、e following steps should be madea part of the standard operating procedure:(a) Stir the 5-gal pail of catalyst 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
45、 sits for 48 h after stirring, stiragain.(d) Start with clean lines and an empty meter/mix machineor purge 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).
46、(f) If a static mix head is used, clean it if the flow ratedecreases substantially. Purging of the static 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 Co
47、ntrolA visual inspection should be con-ducted to ensure that no streaks or excessive air is incorporatedinto 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,th
48、ey should be quick frozen 40F (40C) or below. Thiscan be accomplished by placing the filled cartridges in 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 appr
49、oximately 2 min. Place the frozen tubes in acold box or room at 40F (40C) or below at the manufac-turers 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 pe
