1、Designation: A 742/A 742M 03 (Reapproved 2008)American Association State Highway andTransportation Officials StandardAASHTO No. M 246/M 246MStandard Specification forSteel Sheet, Metallic Coated and Polymer Precoated forCorrugated Steel Pipe1This standard is issued under the fixed designationA 742/A
2、 742M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapp
3、roval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This specification covers polymer precoated steel sheetfor corrugated steel pipe (CSP) which is coated after metalliccoating on continuous lines by coil coating (roller coating orlaminating) processes
4、. The metallic coating is either zinc, 55 %aluminum-zinc alloy, or zinc-5 % aluminum-mischmetal alloy.Sheet for this purpose is furnished flat in coils, flat in cutlengths, or corrugated in cut lengths, all being protected by amill-applied polymer coating on both sides.1.2 The values stated in eithe
5、r inch-pound units or SI unitsare to be regarded separately as the standard. Within the text,the SI units are shown in brackets. The values stated in eachsystem are not equivalents; therefore, each system must beused independently of the other.1.3 The following precautionary caveat refers only to th
6、etest method portion, Section 9, of this specification: Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of reg
7、ulatory limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:2A 929/A 929M Specification for Steel Sheet, Metallic-Coated by the Hot-Dip Process for Corrugated Steel PipeD 543 Practices for Evaluating the Resistance of Plastics toChemical ReagentsD 658 Test Method for Abrasion Resista
8、nce of OrganicCoatings by the Air-Blast Abrasion Test3D 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 2794 Test Method for Resistance of Organic Coatings tothe Effects of Rapid Deformation (Impact)G22 Practice for Determining Resistance of Plastics to
9、Bacteria3G23 Practice for Operating Light-Exposure Apparatus(Carbon-Arc Type) With and Without Water for Exposureof Nonmetallic Materials (Discontinued 2001)3G62 Test Methods for Holiday Detection in Pipeline Coat-ings3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 fabricatori
10、n this specification, fabricator refers tothe producer of the pipe.3.1.2 manufacturerin this specification, manufacturer re-fers to the producer of the sheet.3.1.3 purchaserin this specification, purchaser refers tothe purchaser of the finished pipe.3.2 Abbreviations: Abbreviations:3.2.1 55 Al-Zn55
11、% aluminum-zinc.3.2.2 MMmischmetal.3.2.3 Zn-5 Al-MMzinc-5 % aluminum-mischmetal.4. Classification4.1 The polymer coating is classified by grade correspond-ing to the thickness in mils (thousandths inch) on each side ininch-pound units and the thickness in micrometres on each sidein SI units.Grade Co
12、ating Thicknessin. m10/10 250/250 0.010/0.010 250/2501This specification is under the jurisdiction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products and is the direct responsibility ofSubcommittee A05.17 on Corrugated Steel Pipe Specifications.Current edition approved Nov. 1, 2008. Pub
13、lished December 2008. Originallyapproved in 1977. Last previous edition approved in 2003 as A 742/A 742M 03.2For 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 stan
14、dards Document Summary page onthe ASTM website.3Withdrawn.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 Any combination of polymer coating thickness otherthan sh
15、own above is subject to agreement between the manu-facturer and purchaser or fabricator.5. Ordering Information5.1 The polymer precoated sheet covered by this specifica-tion shall be ordered only to the specified thickness listed inTable 1. The specified thickness is based on the thickness of themet
16、allic-coated steel sheet, not including the thickness of thepolymer coating.5.2 Orders for material to this specification shall include thefollowing information, as necessary, to adequately describe thedesired product.5.2.1 Name of material (polymer precoated steel sheet forCSP),5.2.2 Type of metall
17、ic coating (see 6.1),5.2.3 ASTM designation and year of issue, as A 742 _for inch-pound units or A 742M _ for SI units,5.2.4 Corrugation size, if corrugated (see 6.3),5.2.5 Substrate dimensions (specified thickness; width, ei-ther flat or overall corrugated; and length, if cut length),5.2.6 Grade of
18、 polymer coating (see Section 4), indicatingthickness on each side,5.2.7 Coil size requirements (specify maximum outsidediameter (OD), acceptable inside diameter (ID), and maximumweight),5.2.8 Certification, if required (see 11.1), and5.2.9 Special requirements.NOTE 1Typical ordering descriptions ar
19、e as follows:Polymer precoated steel sheet, zinc-coated for CSP, conforming toASTM A 742 _, 223 by12-in. corrugations, 0.064 by 2512 by 60 in.,with Grade 10/10 polymer coating (0.010 in./0.010 in.), certified with testreport.Polymer precoated steel sheet, aluminum-zinc alloy coated for CSP,conformin
20、g toASTMA 742M _, 2.77 by 700 mm by coil, with Grade250/250 polymer coating; coil 1200-mm max outside diameter, 600-mminside diameter, 10 000-kg max coil weight.6. General Requirements6.1 The metallic-coated substrate shall conform to all appli-cable requirements of Specification A 929/A 929M for zi
21、nccoating, 55 % aluminum-zinc alloy coating, or zinc-5 %aluminum-mischmetal alloy coating, whichever is stated in theorder. If the type of metallic coating is not stated in the order,zinc-coated steel sheet shall be furnished.6.1.1 The steel sheet shall be thoroughly cleaned of anychromate pretreatm
22、ent or other passivation using a multi-brushcleaning process. All traces of the caustic cleaning solutionshall be immediately rinsed from the sheet following causticcleaning. After drying, the steel sheet shall be treated withchromic acid solution and heat-cured prior to application of thepolymer fi
23、lm. The deposited chromium content shall rangefrom 135 to 190 mg/m2.6.2 The polymer coating shall be a film coating comprisedof at least 85 % ethylene acrylic acid copolymer and be capableof being applied to the sheet specified in 6.1.After application,the polymer coating shall be free of holes, tea
24、rs, and discon-tinuities, and shall be sufficiently flexible so that it willwithstand the corrugating, forming, and lockseaming opera-tions, and punching of holes for rivets or perforations.6.3 If the polymer-coated sheet is to be furnished withcorrugations, the corrugations shall conform to the req
25、uire-ments stated in Specification A 929/A 929M.7. Requirements for Polymer Coating7.1 AdhesionThere shall be no spalling or cracking of thecoating, or disbonding of the coating at the cut, when tested inaccordance with 9.1.7.2 ImpactThere shall be no break in the polymer coatingwhen tested in accor
26、dance with 9.2.7.3 Thickness of CoatingThe thickness of the polymercoating shall meet the requirements of Section 4,orasspecified in the purchase order, when tested in accordance with9.3. The thicknesses indicated are minimum values at any pointnot less than38 in. 10 mm from an edge.7.4 HolidaysThe
27、polymer coating on the steel shall besubstantially free of holidays when tested in accordance with9.4. An average of two holidays per square foot 22 holidaysper square metre of actual surface area on the test specimenshall be permitted.NOTE 2Holidays are pinholes or voids in the polymer coating that
28、 arenot visually discernible.7.5 Abrasion ResistanceThe average abrasion coefficientwhen tested in accordance with 9.5, shall be a minimum of 100(expressed in g/mil of thickness) or 3.9 expressed in g/m ofthickness.7.6 ImperviousnessThere shall be no loosening or sepa-ration of the polymer coating f
29、rom the metallic-coated steelsubstrate when tested in accordance with 9.6.7.7 Freeze-Thaw ResistanceThe specimen shall with-stand 100 freeze-thaw cycles, as described in 9.7, withoutspalling, disbonding, or other detrimental effects.7.8 WeatherabilityThe specimens shall withstand 100 h ofweathering
30、with no observable delamination or cracking, whentested in accordance with 9.8.7.9 Resistance to Microbial Attack There shall be noeffect of microbial attack of the polymer coating when tested inaccordance with 9.9.NOTE 3Tests 7.1 through 7.4 are suggested as quality control tests.When these tests a
31、re used for quality control, they may be run at roomtemperature only. Tests 7.5 through 7.9 are suggested as qualifying tests.However, the purchaser may use any of the tests listed to verifycompliance.TABLE 1 Thicknesses of Metallic-Coated Steel SheetASpecifiedThickness,in. mmMetallic CoatingZinc-Co
32、ated55 Al-ZnAlloy CoatedZn-5 Al-MMAlloy Coated0.040 1.02 X X X0.052 1.32 X X X0.064 1.63 X X X0.079 2.01 X X X0.109 2.77 X X X0.138 3.51 X X X0.168 4.27 X XAAn “X” indicates sheet thicknesses which are available in the correspondingcoating type.A 742/A 742M 03 (2008)28. Sampling and Testing8.1 The m
33、anufacturer shall make adequate tests and mea-surements to ensure that the material produced complies withthis specification.8.1.1 Test results to show compliance with this specificationshall be retained by the manufacturer for seven years and shallbe made available to the fabricator and purchaser u
34、pon request.8.2 The fabricator or purchaser shall conduct such tests asare determined necessary to determine the acceptability of thematerial or to verify the correctness of a certification.8.3 Flat samples of polymer precoated steel shall be takenby the manufacturer from each coil or in accordance
35、with thesampling procedure as mutually agreed upon between themanufacturer and the purchaser. Each sample shall be at least24 in. 600 mm long by the coil width and shall carry anidentification to relate it to the coil from which it was taken.9. Test Methods for Polymer Coatings9.1 Adhesion:9.1.1 Sco
36、peThis procedure measures the adhesion of thepolymer coating to the metallic-coated substrate.9.1.2 Significance and UseThis test indicates the abilityof the polymer to withstand forces in fabrication and usetending to disbond the coating from the substrate.9.1.3 ProcedureCuta2by8-in. 50 by 200-mm c
37、ouponfrom the sample of precoated steel. Bend the coupon 180 overa 0.5-in. 12.5-mm diameter mandrel. The surface with thepolymer coating to be tested shall be on the outside of the bend.After making bend, make a cut through the polymer coatingalong an element on the outside of the bend to check forp
38、olymer coating adhesion. Perform this test at 0, 77, and 122 62F 18, 25, and 50 6 1C. Check for spalling or cracking ofthe polymer coating, or for disbonding from the metallic-coated substrate.9.1.4 Precision and BiasNo statement is made abouteither the precision or the bias of the procedure for mea
39、suringadhesion since the result merely states whether there isconformance to the criteria for success specified in the proce-dure.9.2 Impact:9.2.1 ScopeThis procedure measures the ability of thepolymer coating to withstand impact.9.2.2 Significance and UseThis test provides a measure ofthe ability o
40、f the polymer coating to resist damage by impact,to which it may be subjected in service.9.2.3 ProcedureCuta6by6-in. 150 by 150-mm couponfrom the sample of precoated steel. Direct impact the coatingwith an energy of 35 in.lb 4.0 J using an impact tester4witha 0.625-in. 15.88-mm diameter punch and wi
41、th the specimenset on a 0.640-in. 16.26-mm diameter punch die. Test atapproximately 77F 25C (Note 4). Check for breaks in thepolymer coating.NOTE 4This test procedure is described in detail in Test MethodD 2794.9.2.4 Precision and BiasNo statement is made abouteither the precision or the bias of the
42、 procedure for measuringimpact resistance since the result merely states whether there isconformance to the criteria for success specified in the process.9.3 Thickness of CoatingMeasure polymer coating thick-ness in accordance with Test Methods D 1005.9.4 HolidaysTest a specimen that is at least 12
43、in. 300mm long and the full coil width in accordance with PracticeG62, Method A, using a nominal voltage of 6712 V.9.5 Abrasion ResistanceDetermine the abrasion coeffi-cient in accordance with Test Method D 658 except use asilicon carbide grain passing a No. 140 106-m sieve andretained on a No. 170
44、90-m sieve, and an air test pressure of4.82 psi 250 mm Hg 33.25 kPa.9.5.1 The modifications to the procedure in Test MethodD 658 are not expected to have an effect on the precision andbias as indicated in Test Method D 658.9.6 ImperviousnessTest the polymer coating for impervi-ousness to chemical re
45、agents in accordance with the applicablesections of Practices D 543 using a 10 % solution of sodiumchloride, a 10 % solution of sodium hydroxide, and a 30 %solution of sulfuric acid. Hold each reagent in a separateconfined area of the polymer precoated sheet for a period of 48h. Avoid excessive evap
46、oration of the test solutions.9.7 Freeze-Thaw Resistance:9.7.1 ScopeThis procedure evaluates the ability of thepolymer coating to resist freeze-thaw cycling.9.7.2 Significance and UseAs pipe fabricated frompolymer-coated steel sheet will be exposed to freeze-thawaction while saturated, the procedure
47、 will measure ability towithstand such action without damage to the polymer coating.9.7.3 ProcedureCut a minimum of three 6 by 6-in. 150by 150-mm coupons from the sample of precoated metal.Immerse the coupons in water at room temperature for twoweeks and then subject them to freeze-thaw cycling. One
48、 cycleshall consist of8hat0F18C followed immediately byimmersion in water at room temperature for 16 h. Cycle timemay be interrupted over weekends and holidays, but thespecimens shall be maintained in water at room temperature,and such interruptions should be noted. Make observationsduring the cycli
49、ng and note any visible changes in the coating,such as spalling, disbonding, etc.After 100 cycles, make a finalexamination of the effects as a result of freezing and thawing.9.7.4 Precision and BiasNo statement is made abouteither the precision or the bias of the procedure for measuringfreeze-thaw resistance since the result merely states whetherthere is conformance to the criteria for success specified in theprocedure.9.8 WeatherabilitySubject coupons
