1、Designation: A742/A742M 03 (Reapproved 2008)A742/A742M 13American 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 designa
2、tion A742/A742M; 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 revisio
3、n or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This specification covers polymer precoated steel sheet for corrugated steel pipe (CSP) which is coated after metallic coatingon continuous lines by coil coating (roller coating or laminatin
4、g) processes. 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 cut lengths,or corrugated in cut lengths, all being protected by a mill-applied polymer coating on both sides.1.2 The values s
5、tated in either inch-pound units or SI units are to be regarded separately as the standard. Within the text, theSI units are shown in brackets. The values stated in each system are not equivalents; therefore, each system must be usedindependently of the other.1.3 The following precautionary caveat r
6、efers only to the test method portion, Section 9, of this specification:This standard doesnot purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices and determine the ap
7、plicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A929/A929M Specification for Steel Sheet, Metallic-Coated by the Hot-Dip Process for Corrugated Steel PipeD543 Practices for Evaluating the Resistance of Plastics to Chemical ReagentsD658 Test Method for Ab
8、rasion Resistance of Organic Coatings by Air Blast Abrasive (Withdrawn 1996)3D1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using MicrometersD2794 Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact)G22 Practice for Determining Resi
9、stance of Plastics to Bacteria (Withdrawn 2002)3G23 Practice for Operating Light-ExposureApparatus (Carbon-Arc Type) With and Without Water for Exposure of NonmetallicMaterials (Withdrawn 2000)3G62 Test Methods for Holiday Detection in Pipeline Coatings3. Terminology3.1 Definitions of Terms Specific
10、 to This Standard:3.1.1 fabricatorin this specification, fabricator refers to the producer of the pipe.3.1.2 manufacturerin this specification, manufacturer refers to the producer of the sheet.3.1.3 purchaserin this specification, purchaser refers to the purchaser of the finished pipe.3.2 Abbreviati
11、ons:3.2.1 55 Al-Zn55 % aluminum-zinc.3.2.2 MMmischmetal.1 This specification is under the jurisdiction ofASTM Committee A05 on Metallic-Coated Iron and Steel Products and is the direct responsibility of Subcommittee A05.17on Corrugated Steel Pipe Specifications.Current edition approved Nov. 1, 2008A
12、pril 1, 2013. Published December 2008April 2013. Originally approved in 1977. Last previous edition approved in 20032008 asA742/A742M 03.A742/A742M 03 (2008). DOI: 10.1520/A0742_A0742M-03R08.10.1520/A0742_A0742M-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM C
13、ustomer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only t
14、o provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versiono
15、f the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 Zn-5 Al-MMzinc-5 % aluminum-mischmeta
16、l.4. Classification4.1 The polymer coating is classified by grade corresponding to the thickness in mils (thousandths inch) on each side ininch-pound units and the thickness in micrometres on each side in SI units.Grade Coating Thicknessin. m10/10 250/250 0.010/0.010 250/2504.2 Any combination of po
17、lymer coating thickness other than shown above is subject to agreement between the manufacturerand purchaser or fabricator.5. Ordering Information5.1 The polymer precoated sheet covered by this specification shall be ordered only to the specified thickness listed in Table1. The specified thickness i
18、s based on the thickness of the metallic-coated steel sheet, not including the thickness of the polymercoating.5.2 Orders for material to this specification shall include the following information, as necessary, to adequately describe thedesired product.5.2.1 Name of material (polymer precoated stee
19、l sheet for CSP),5.2.2 Type of metallic coating (see 6.1),5.2.3 ASTM designation and year of issue, as A742 _ for inch-pound units or A742M _ for SI units,5.2.4 Corrugation size, if corrugated (see 6.3),5.2.5 Substrate dimensions (specified thickness; width, either flat or overall corrugated; and le
20、ngth, if cut length),5.2.6 Grade of polymer coating (see Section 4), indicating thickness on each side,5.2.7 Coil size requirements (specify maximum outside diameter (OD), acceptable inside diameter (ID), and maximum weight),5.2.8 Certification, if required (see 11.1), and5.2.9 Special requirements.
21、NOTE 1Typical ordering descriptions are as follows:Polymer precoated steel sheet, zinc-coated for CSP, conforming toASTM A742 _, 223 by 12-in. corrugations, 0.064 by 2512 by 60 in., with Grade10/10 polymer coating (0.010 in./0.010 in.), certified with test report.Polymer precoated steel sheet, alumi
22、num-zinc alloy coated for CSP, conforming toASTM A742M _, 2.77 by 700 mm by coil, with Grade 250/250polymer coating; coil 1200-mm max outside diameter, 600-mm inside diameter, 10 000-kg max coil weight.6. General Requirements6.1 The metallic-coated substrate shall conform to all applicable requireme
23、nts of Specification A929/A929M for zinc coating,55 % aluminum-zinc alloy coating, or zinc-5 % aluminum-mischmetal alloy coating, whichever is stated in the order. If the typeof metallic coating is not stated in the order, zinc-coated steel sheet shall be furnished.6.1.1 The steel sheet shall be tho
24、roughly cleaned of any chromate pretreatment or other passivation using a multi-brush cleaningprocess. All traces of the caustic cleaning solution shall be immediately rinsed from the sheet following caustic cleaning. Afterdrying, the steel sheet shall be treated with chromic acid solution and heat-
25、cured prior to application of the polymer film. Thedeposited chromium content shall range from 135 to 190 mg/m2.6.2 The polymer coating shall be a laminated film coating comprised of at least 85 % 85 % ethylene acrylic acid copolymer orat least 25 % Maleic Anhydride Grafted Polymer, which is partial
26、ly hydrolyzed and be capable of being applied to the sheetTABLE 1 Thicknesses of Metallic-Coated Steel SheetASpecifiedThickness,in. mmMetallic CoatingZinc-Coated 55 Al-ZnAlloy Coated Zn-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
27、X0.168 4.27 X XAAn “X” indicates sheet thicknesses which are available in the correspondingcoating type.A742/A742M 132specified in 6.1. After application, the polymer coating shall be free of holes, tears, and discontinuities, and shall be sufficientlyflexible so that it will withstand the corrugati
28、ng, forming, and lockseaming operations, and punching of holes for rivets orperforations.6.3 If the polymer-coated sheet is to be furnished with corrugations, the corrugations shall conform to the requirements statedin Specification A929/A929M.7. Requirements for Polymer Coating7.1 AdhesionThere sha
29、ll be no spalling or cracking of the coating, or disbonding of the coating at the cut, when tested inaccordance with 9.1.7.2 ImpactThere shall be no break in the polymer coating when tested in accordance with 9.2.7.3 Thickness of CoatingThe thickness of the polymer coating shall meet the requirement
30、s of Section 4, or as specified in thepurchase order, when tested in accordance with 9.3. The thicknesses indicated are minimum values at any point not less than 38in. 10 mm from an edge.7.4 HolidaysThe polymer coating on the steel shall be substantially free of holidays when tested in accordance wi
31、th 9.4. Anaverage of two holidays per square foot 22 holidays per square metre of actual surface area on the test specimen shall bepermitted.NOTE 2Holidays are pinholes or voids in the polymer coating that are not visually discernible.7.5 Abrasion ResistanceThe average abrasion coefficient when test
32、ed in accordance with 9.5, shall be a minimum of 100(expressed in g/mil of thickness) or 3.9 expressed in g/m of thickness.7.6 ImperviousnessThere shall be no loosening or separation of the polymer coating from the metallic-coated steel substratewhen tested in accordance with 9.6.7.7 Freeze-Thaw Res
33、istanceThe specimen shall withstand 100 freeze-thaw cycles, as described in 9.7, without spalling,disbonding, or other detrimental effects.7.8 WeatherabilityThe specimens shall withstand 100 h of weathering with no observable delamination or cracking, whentested in accordance with 9.8.7.9 Resistance
34、 to Microbial Attack There shall be no effect 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 room temperatureonly. Tests 7.5 through 7.9
35、 are suggested as qualifying tests. However, the purchaser may use any of the tests listed to verify compliance.8. Sampling and Testing8.1 The manufacturer shall make adequate tests and measurements to ensure that the material produced complies with thisspecification.8.1.1 Test results to show compl
36、iance with this specification shall be retained by the manufacturer for seven years and shall bemade available to the fabricator and purchaser upon request.8.2 The fabricator or purchaser shall conduct such tests as are determined necessary to determine the acceptability of thematerial or to verify
37、the correctness of a certification.8.3 Flat samples of polymer precoated steel shall be taken by the manufacturer from each coil or in accordance with thesampling procedure as mutually agreed upon between the manufacturer and the purchaser. Each sample shall be at least 24 in. 600mm long by the coil
38、 width and shall carry an identification 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 the polymer coating to the metallic-coated substrate.9.1.2 Significance and UseThis test indicates the ability
39、 of the polymer to withstand forces in fabrication and use tending todisbond the coating from the substrate.9.1.3 ProcedureCut a 2 by 8-in. 50 by 200-mm coupon from the sample of precoated steel. Bend the coupon 180 over a0.5-in. 12.5-mm diameter mandrel. The surface with the polymer coating to be t
40、ested shall be on the outside of the bend. Aftermaking bend, make a cut through the polymer coating along an element on the outside of the bend to check for polymer coatingadhesion. Perform this test at 0, 77, and 12262F 18, 25, and 5061C. Check for spalling or cracking of the polymer coating,or for
41、 disbonding from the metallic-coated substrate.9.1.4 Precision and BiasNo statement is made about either the precision or the bias of the procedure for measuring adhesionsince the result merely states whether there is conformance to the criteria for success specified in the procedure.9.2 Impact:A742
42、/A742M 1339.2.1 ScopeThis procedure measures the ability of the polymer coating to withstand impact.9.2.2 Significance and UseThis test provides a measure of the ability of the polymer coating to resist damage by impact, towhich it may be subjected in service.9.2.3 ProcedureCut a 6 by 6-in. 150 by 1
43、50-mm coupon from the sample of precoated steel. Direct impact the coating withan energy of 35 in.lb 4.0 J using an impact tester4 with a 0.625-in. 15.88-mm diameter punch and with the specimen set ona 0.640-in. 16.26-mm diameter punch die. Test at approximately 77F 25C (Note 4). Check for breaks in
44、 the polymer coating.NOTE 4This test procedure is described in detail in Test Method D2794.9.2.4 Precision and BiasNo statement is made about either the precision or the bias of the procedure for measuring impactresistance since the result merely states whether there is conformance to the criteria f
45、or success specified in the process.9.3 Thickness of CoatingMeasure polymer coating thickness in accordance with Test Methods D1005.9.4 HolidaysTest a specimen that is at least 12 in. 300 mm long and the full coil width in accordance with Practice G62,Method A, using a nominal voltage of 6712 V.9.5
46、Abrasion ResistanceDetermine the abrasion coefficient in accordance with Test Method D658 except use a silicon carbidegrain passing a No. 140 106-m sieve and retained on a No. 170 90-m sieve, and an air test pressure of 4.82 psi 250 mmHg 33.25 kPa.9.5.1 The modifications to the procedure in Test Met
47、hod D658 are not expected to have an effect on the precision and bias asindicated in Test Method D658.9.6 ImperviousnessTest the polymer coating for imperviousness to chemical reagents in accordance with the applicablesections of Practices D543 using a 10 % solution of sodium chloride, a 10 % soluti
48、on of sodium hydroxide, and a 30 % solutionof sulfuric acid. Hold each reagent in a separate confined area of the polymer precoated sheet for a period of 48 h.Avoid excessiveevaporation of the test solutions.9.7 Freeze-Thaw Resistance:9.7.1 ScopeThis procedure evaluates the ability of the polymer co
49、ating to resist freeze-thaw cycling.9.7.2 Significance and UseAs pipe fabricated from polymer-coated steel sheet will be exposed to freeze-thaw action whilesaturated, the procedure will measure ability to withstand such action without damage to the polymer coating.9.7.3 ProcedureCut a minimum of three 6 by 6-in. 150 by 150-mm coupons from the sample of precoated metal. Immersethe coupons in water at room temperature for two weeks and then subject them t
