1、Designation: A 742/A 742M 03American 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 designationA742/A742M; the number im
2、mediately 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 (e) indicates an editorial change since the last revision or reapproval.This standard
3、 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. The metallic coat
4、ing 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 either inch-pound units
5、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 thetest method portio
6、n, 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 regulatory limita-tion
7、s 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 Resistance of OrganicCoati
8、ngs by the Air-Blast Abrasion TestD 1005 Test Methods for Measurement of DryFilm Thick-ness of Organic Coatings Using MicrometersD 2794 Test Method for Resistance of Organic Coatings onthe Effects of Rapid Deformation (Impact)G22 Practice for Determining Resistance of Plastics toBacteriaG23 Practice
9、 for Operating Light- and Water-ExposureApparatus (Carbon-Arc Type) for Exposure of Nonmetal-lic MaterialsG62 Test Methods for Holiday Detection in Pipeline Coat-ings3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 fabricatorin this specification, fabricator refers tothe produc
10、er 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 % aluminum-zinc.3.2.2 MMmischmetal.3.2.3 Zn-5 Al-MMz
11、inc-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 Coating Thicknessin. m10/10 250/250 0.010/0.010 250/25
12、04.2 Any combination of polymer coating thickness otherthan shown above is subject to agreement between the manu-facturer and purchaser or fabricator.1This specification is under the jurisdiction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products and is the direct responsibility ofSubco
13、mmittee A05.17 on Corrugated Steel Pipe Specifications.Current edition approved April 10, 2003. Published May 2003. Originallyapproved in 1977. Last previous edition approved in 1998 as A 742/A 742M 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv
14、ice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.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 1942
15、8-2959, United States.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 themetallic-coated steel sheet, not including the thickness of thepolyme
16、r 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 metallic coating (see 6.1),5.2.3 ASTM designation and year of issue, as
17、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 polymer coating (see Section 4), indicatingthickness on each side
18、,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 are as follows:Polymer precoated steel sheet, zinc-coated for CSP, c
19、onforming 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,conforming toASTMA 742M _, 2.77 by 700 mm by coil, with Grade250/250 polyme
20、r 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 zinccoating, 55 % aluminum-zinc alloy coating, or zinc-5 %aluminum-m
21、ischmetal 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 pretreatment or other passivation using a multi-brushcleaning process. All
22、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 film. The deposited chromium content shall rangefrom 135 to 190 mg/m
23、2.6.2 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, tears, and discon-tinuities, and shall be sufficiently flexible so th
24、at 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 require-ments stated in Specification A 929/A 929M.7. Requirements fo
25、r 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 accordance with 9.2.7.3 Thickness of CoatingThe thickness of the polyme
26、rcoating 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 polymer coating on the steel shall besubstantially free of holiday
27、s 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 arenot visually discernible.7.5 Abrasion ResistanceThe average ab
28、rasion 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 from the metallic-coated steelsubstrate when tested in accordance w
29、ith 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 with no observable delamination or cracking, whentested in accorda
30、nce 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 are used for quality control, they may be run at roomtemperature on
31、ly. Tests 7.5 through 7.9 are suggested as qualifying tests.However, the purchaser may use any of the tests listed to verifycompliance.8. Sampling and Testing8.1 The manufacturer shall make adequate tests and mea-surements to ensure that the material produced complies withthis specification.TABLE 1
32、Thicknesses of Metallic-Coated Steel SheetASpecifiedThickness,in. mmMetallic CoatingZinc-Coated55 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 availab
33、le in the correspondingcoating type.A 742/A 742M 0328.1.1 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 upon request.8.2 The fabricator or purchaser shall conduct such tests asar
34、e 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 with thesampling procedure as mutually agreed upon between themanufacture
35、r 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 ScopeThis procedure measures the adhesion of thepolymer coating to the metal
36、lic-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 couponfrom the sample of precoated steel. Bend the coupon 180 overa 0.5-in
37、. 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 forpolymer coating adhesion. Perform this test at 0, 77, and 122 62F 18, 25,
38、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 measuringadhesion since the result merely states whether there isconformance
39、 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 of the polymer coating to resist damage by impact,to which it may be subje
40、cted 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 tester3witha 0.625-in. 15.88-mm diameter punch and with the specimenset on a 0.640-in. 16.26-mm diameter punch die. Test atapp
41、roximately 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 procedure for measuringimpact resistance since the result merely states
42、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 in. 300mm long and the full coil width in accordance with PracticeG62, Me
43、thod 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 90-m sieve, and an air test pressure of4.82 psi 250 mm Hg 33.25 kPa.9.5.1
44、 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 reagents in accordance with the applicablesections of Practices D 543 using
45、 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 evaporation of the test solutions.9.7 Freeze-Thaw Resistance:9.7.1 ScopeThis
46、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 will measure ability towithstand such action without damage to the polym
47、er 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 cycleshall consist of8hat0F18C followed immediately byimmersion in water
48、 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 cycling and note any visible changes in the coating,such as spalling, disbondi
49、ng, 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 of the precoated metalto accelerated weathering in accordance with Pract
