1、Standard Specification for Steel Sheet, Metallic-Coated and Polymer-Precoated, for Corrugated Steel Pipe AASHTO Designation: M 246-15 ASTM Designation: A742/A742M-13 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-
2、4b M 246-1 AASHTO Standard Specification for Steel Sheet, Metallic-Coated and Polymer-Precoated, for Corrugated Steel Pipe AASHTO Designation: M 246-15 ASTM Designation: A742/A742M-13 1. SCOPE 1.1. This specification covers polymer-precoated steel sheet for corrugated steel pipe (CSP), which is coat
3、ed after metallic coating on continuous lines by coil coating (roller coating or laminating) processes. The metallic coating is either zinc or aluminum-zinc 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-appl
4、ied polymer coating on one or both sides. 1.2. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to establish appropriate safet
5、y and health practices and to determine the applicability of regulatory limitations prior to its use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 218, Steel Sheet, Zinc-Coated (Galvanized), for Corrugated Steel Pipe M 289, Aluminum-Zinc Alloy Coated Sheet Steel for Corrugated Steel Pipe 2.2. AS
6、TM Standards: A929/A929M, Standard Specification for Steel Sheet, Metallic-Coated by the Hot-Dip Process for Corrugated Steel Pipe D543, Standard Practices for Evaluating the Resistance of Plastics to Chemical Reagents D658, Standard Test Method for Abrasion Resistance of Organic Coatings by Air Bla
7、st Abrasive (Withdrawn 1996) D1005, Standard Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers D2794, Standard Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact) G22, Standard Practice for Determining Resistance of Plasti
8、cs to Bacteria (Withdrawn 2002) G23, Practice for Operating Light-Exposure Apparatus (Carbon-Arc Type) With and Without Water for Exposure of Nonmetallic Materials (Withdrawn 2000) G62, Standard Test Methods for Holiday Detection in Pipeline Coatings (Withdrawn 2007) 2015 by the American Association
9、 of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4b M 246-2 AASHTO 3. CLASSIFICATION 3.1. The polymer coating is classified by grade corresponding to the thickness micrometers on each side in SI units, and the thickness in mils on ea
10、ch side in inch-pound units (see Table 1). Table 1Polymer Coating Grade Coating Thickness, m 250/250 250/250 3.2. Any combination of polymer coating thickness other than shown in Table 1 is subject to agreement between the manufacturer and purchaser or fabricator. 4. TERMINOLOGY 4.1. In this specifi
11、cation, manufacturer refers to the producer of the sheet, fabricator refers to the producer of the pipe, and purchaser refers to the purchaser of the finished pipe. 5. ORDERING INFORMATION 5.1. The polymer-precoated sheet covered by this specification shall be ordered only to the specified thickness
12、es listed in Table 2. The specified thickness is based on the thickness of the metallic-coated steel sheet, not including the thickness of the polymer coating. Table 2Thicknesses of Metallic-Coated Steel Plate Specified Thickness Specification Designation M 218, Zinc-Coated M 289, 55% Aluminum-Zinc
13、Alloy Coated A929/A929M, Zn-5 Al-MM Alloy Coated mm in. 1.02 0.040 X X X 1.32 0.052 X X X 1.63 0.064 X X X 2.01 0.079 X X X 2.77 0.109 X X X 3.51 0.138 X X X 4.27 0.168 X X Note: An “X” indicates sheet thickness included in the applicable specification. 5.2. Orders for material to this specification
14、 shall include the following information, as necessary, to adequately describe the desired product: 5.2.1. Name of material (polymer-precoated steel sheet for CSP); 5.2.2. Type of metallic coating (Section 6.1); 5.2.3. AASHTO designation number and date of issue; 5.2.4. Corrugation size, if corrugat
15、ed (Section 6.3); 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4b M 246-3 AASHTO 5.2.5. Substrate dimensions (specified thickness; width, either flat or overall corrugated; and length, if cut lengt
16、h); 5.2.6. Grade of polymer coating (Section 3) indicating thickness on each side; 5.2.7. Coil size requirements (specify maximum outside diameter (OD), acceptable inside diameter (ID), and maximum mass); 5.2.8. Certification, if required (Section 11.1); and 5.2.9. Special requirements. Note 1Typica
17、l ordering descriptions are as follows: Polymer-precoated steel sheet, aluminum-zinc alloy coated for CSP, conforming to M 246-_, 2.77 by 700 mm by coil, with Grade 250 polymer coating (0.25 mm); coil 1200 mm max OD, 600 mm ID, 10 000 kg max coil mass. Polymer-precoated steel sheet, zinc-coated for
18、CSP, conforming to M 246-_. 6. GENERAL REQUIREMENTS 6.1. The metallic-coated steel substrate shall conform to all applicable requirements of the specification listed below for the kind of metallic coating specified. If the type of metallic coating is not stated in the order, zinc-coated sheet as des
19、cribed in Section 6.1.1 shall be furnished. 6.1.1. Zinc CoatingZinc-coated steel sheet shall conform to the requirements of M 218. 6.1.2. Aluminum-Zinc Alloy Coating 55Aluminum-zinc alloy coated steel sheet shall conform to the requirements of M 289 and zinc-5 aluminum-MM alloy coated steel sheets s
20、hall conform to the requirements of ASTM A929/A929M. 6.1.3. The steel sheet shall be thoroughly cleaned of any chromate pretreatment or other passivation using a multi-brush cleaning process. All traces of the caustic cleaning solution shall be immediately rinsed from the sheet following caustic cle
21、aning. After drying, the steel sheet shall be treated with chromic acid solution and heat-cured prior to application of the polymer film. The deposited chromium content shall range from 135 to 190 mg/m2. 6.2. The polymer coating shall be a film coating composed of at least 85 percent ethylene acryli
22、c acid (EAA) copolymer or at least 25 percent Maleic Anhydride (MAH) Grafted Polymer, which is partially hydrolyzed. The polymer coating shall be capable of being applied to the sheet specified in Section 6.1. After application, the polymer coating shall be free of holes, tears, and discontinuities,
23、 and shall be sufficiently flexible so that it will withstand the corrugating, forming, and lock-seaming operations as well as the punching of holes for rivets or perforations. Note 2The MAH grafted polymer coating is only applied over zinc-coated steel conforming to the requirements of Section 6.1.
24、1. 6.3. If the polymer-coated sheet is to be furnished with corrugations, the corrugations shall conform to the requirements stated in the appropriate specification listed in Section 6.1. 7. REQUIREMENTS FOR POLYMER COATINGS 7.1. AdhesionThere shall be no spalling or cracking of the coating when tes
25、ted in accordance with Section 9.1. There shall be no disbonding of the coating at the cut to be made as described in Section 9.1. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4b M 246-4 AASHTO 7.2
26、. ImpactThere shall be no break in the polymer coating when tested in accordance with Section 9.2. 7.3. Thickness of CoatingThe thickness of the polymer coating shall meet the requirements of Section 3, or as specified in the purchase order, when tested in accordance with Section 9.3. 7.4. HolidaysT
27、he polymer coating on the steel shall be substantially free of holidays when tested in accordance with Section 9.4. An average of 22 holidays per square meter of actual surface area on the test specimen shall be permitted. Note 3Holidays are pinholes or voids in the polymer coating that are not visu
28、ally discernible. 7.5. Abrasion ResistanceThe average abrasion coefficient, when tested in accordance with Section 9.5, shall be a minimum of 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 substr
29、ate when tested in accordance with Section 9.6. 7.7. FreezeThaw ResistanceThe specimen shall withstand 100 freezethaw cycles, as described in Section 9.7, without spalling, disbonding, or other detrimental effects. 7.8. WeatherabilityThe specimens shall withstand 1000 h of weathering with no observa
30、ble delamination or cracking, when tested in accordance with Section 9.8. 7.9. Resistance to Microbial AttackThere shall be no effect of microbial attack of the polymer coating when tested in accordance with Section 9.9. Note 4Tests 7.1 through 7.4 are suggested as quality control tests. When these
31、tests are used for quality control, they may be run at room temperature only. Tests 7.5 through 7.9 are suggested as qualifying tests. However, the purchaser may use any of the tests listed to verify compliance. 8. SAMPLING AND TESTING 8.1. The manufacturer shall make tests and measurements adequate
32、 to ensure that the material produced complies with this specification. 8.1.1. Test results to show compliance with this specification shall be retained by the manufacturer for 7 years and shall be made available to the fabricator and purchaser upon request. 8.2. The purchaser of the sheet (fabricat
33、or), or purchaser of the pipe made from the sheet, may make such tests as are deemed necessary to determine the acceptability of the material or to verify the correctness of a certification. 8.3. Flat samples of polymer-precoated steel shall be taken by the manufacturer from each coil or in accordan
34、ce with the sampling procedure as mutually agreed between manufacturer and purchaser. Each sample shall be at least 600 mm long by the coil width and shall carry an identification to relate it to the coil from which it was taken. 9. TEST METHODS FOR POLYMER COATINGS 9.1. Adhesion: 9.1.1. ScopeThis p
35、rocedure is to measure the adhesion of the polymer coating to the metallic-coated substrate. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4b M 246-5 AASHTO 9.1.2. Significance and UseThis test indi
36、cates the ability of the polymer to withstand forces in fabrication and use tending to disbond the coating from the substrate. 9.1.3. ProcedureCut a 50-by-200-mm coupon from the sample of precoated steel. Bend the coupon 180 degrees over a 12.5-mm diameter mandrel. The surface with the polymer coati
37、ng to be tested shall be on the outside of the bend. After making the bend, make a cut through the polymer coating along an element on the outside of the bend to check for polymer coating adhesion. Perform this test at 18C, 25C, and 50C 1C. Check for spalling or cracking of the polymer coating, or f
38、or 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 adhesion since the result merely states whether there is conformance to the criteria for success specified in the procedure. 9.2. Impa
39、ct: 9.2.1. ScopeThis procedure is to measure 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, to which it may be subjected in service, in order to determine brittleness of
40、 the polymer coating. 9.2.3. ProcedureCut a 150-by-150-mm coupon from the sample of precoated steel to be used for fabrication of the pipe. Direct impact the coating with an energy of 4.0 J using an impact tester1with a 15.88-mm diameter punch and with the specimen set on a 16.26-mm diameter punch d
41、ie. Test at approximately 25C (Note 5). Check for breaks in the polymer coating. Note 5This test procedure is described in detail in ASTM D2794. 9.2.4. Precision and BiasNo statement is made about either the precision or the bias of the procedure for measuring impact resistance since the result mere
42、ly states whether there is conformance to the criteria for success specified in the procedure. 9.3. Thickness of CoatingMeasure polymer coating thickness in accordance with ASTM D1005. 9.4. HolidaysTest a specimen that is at least 300 mm long and the full coil width in accordance with ASTM G62, Meth
43、od A, using a nominal voltage of 67.5 volts. 9.5. Abrasion ResistanceDetermine the abrasion coefficient in accordance with ASTM D658 except use a silicon carbide grain passing a 106-m sieve and retained on a 90-m sieve, and an air test pressure of 33.25 kPa (250 mmHg). 9.5.1. The modifications to th
44、e procedure in ASTM D658 are not expected to have an effect on the precision and bias as indicated in ASTM D658. 9.6. ImperviousnessTest the polymer coating for imperviousness to chemical reagents in accordance with the applicable sections of ASTM D543 using a 10 percent solution of sodium chloride,
45、 a 10 percent solution of sodium hydroxide, and a 30 percent solution of sulfuric acid. Hold each reagent in a separate confined area of the polymer-precoated sheet for a period of 48 h. Avoid excessive evaporation of the test solutions. 9.7. FreezeThaw Resistance: 9.7.1. ScopeThis procedure is to e
46、valuate the ability of the polymer coating to resist freezethaw cycling. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4b M 246-6 AASHTO 9.7.2. Significance and UseAs pipe fabricated from polymer-co
47、ated steel sheet will be exposed to freezethaw action while saturated, the procedure will measure ability to withstand such action without damage to the polymer coating. 9.7.3. ProcedureCut a minimum of three 150-by-150-mm coupons from the sample of precoated metal. Immerse the coupons in water at r
48、oom temperature for 2 weeks and then subject them to freezethaw cycling. One (1) cycle shall consist of 8 h at 18C followed immediately by immersion in water at room temperature for 16 h. Cycle time may be interrupted over weekends and holidays, but the specimens shall be maintained in water at room
49、 temperature, and such interruptions should be noted. Make observations during the cycling and note any visible changes in the coating, such as spalling, disbonding, etc. After 100 cycles, make a final examination of the effects as a result of freezing and thawing. 9.7.4. Precision and BiasNo statement is made about either the precision or the bias of the procedure for measuring freezethaw resistance since the result merely states whether there is conformance to the criteria for success specified in
