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1、 AS/NZS 4791:2006 Australian/New Zealand Standard Hot-dip galvanized (zinc) coatings on ferrous open sections, applied by an in-line process AS/NZS 4791:2006 Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 AS/NZS 4791:2006 This Joint Australian/New Zealand Standard was prepared by Joint Tec
2、hnical Committee MT-009, Metal Finishing. It was approved on behalf of the Council of Standards Australia on 19 June 2006 and on behalf of the Council of Standards New Zealand on 14 July 2006. This Standard was published on 25 July 2006. The following are represented on Committee MT-009: Australian
3、Institute of Metal Finishing Australian Aluminium Council Australian Industry Group Australian Paint Manufacturers Federation Department of Defence Galvanizers Association of Australia Powder Coaters Association The Royal Australian Chemical Institute Society of Automotive EngineersAustralasia Keepi
4、ng Standards up-to-date Standards are living documents which reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is im
5、portant that readers assure themselves they are using a current Standard, which should include any amendments which may have been published since the Standard was purchased. Detailed information about joint Australian/New Zealand Standards can be found by visiting the Standards Web Shop at .au or St
6、andards New Zealand web site at www.standards.co.nz and looking up the relevant Standard in the on-line catalogue. Alternatively, both organizations publish an annual printed Catalogue with full details of all current Standards. For more frequent listings or notification of revisions, amendments and
7、 withdrawals, Standards Australia and Standards New Zealand offer a number of update options. For information about these services, users should contact their respective national Standards organization. We also welcome suggestions for improvement in our Standards, and especially encourage readers to
8、 notify us immediately of any apparent inaccuracies or ambiguities. Please address your comments to the Chief Executive of either Standards Australia or Standards New Zealand at the address shown on the back cover. This Standard was issued in draft form for comment as DR 05560. Accessed by UNIVERSIT
9、Y OF SOUTH AUSTRALIA on 02 Apr 2008 AS/NZS 4791:2006 Australian/New Zealand Standard Hot-dip galvanized (zinc) coatings on ferrous open sections, applied by an in-line process Originated as AS/NZS 4791:1999. Second edition 2006. COPYRIGHT Standards Australia/Standards New Zealand All rights are rese
10、rved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher. Jointly published by Standards Australia, GPO Box 476, Sydney, NSW 2001 and Standards New Zealand, Private Bag 2439,
11、Wellington 6020 ISBN 0 7337 7643 4 Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 AS/NZS 4791:2006 2 PREFACE This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee MT-009, Metal Finishing, to supersede AS/NZS 4791:1999, Hot-dip galvanized (zinc) coating
12、s on ferrous open sections, applied by an in-line process. The objective of this revision is to revise the hot-dip galvanized coating specifications. There are no International (ISO) Standards covering these specialized processes. The terms normative and informative have been used in this Standard t
13、o define the application of the appendix to which they apply. A normative appendix is an integral part of a Standard, whereas an informative appendix is only for information and guidance. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 3 AS/NZS 4791:2006 CONTENTS Page 1 SCOPE4 2 REFERENCED
14、DOCUMENTS4 3 DEFINITIONS5 4 GALVANIZING PROCESS.6 5 APPEARANCE AND FREEDOM FROM DEFECTS6 6 DESIGNATION7 7 SELECTION OF TEST SPECIMENS7 8 COATING MASS AND THICKNESS.7 9 ADHERENCE OF COATING8 APPENDICES A PURCHASING GUIDELINES 10 B MEANS FOR DEMONSTRATING COMPLIANCE WITH THIS STANDARD. 11 C GENERAL IN
15、FORMATION ON FACTORS THAT AFFECT THE CORROSION OF GALVANIZED STEEL. 13 D RENOVATION OF DAMAGED OR UNCOATED AREAS 16 E TRANSPORT AND STORAGE OF GALVANIZED OPEN SECTIONS. 17 F DETERMINATION OF COATING MASS AND LOCAL THICKNESS. 18 G DUPLEX ADDED PROTECTION FOR GALVANIZING PLACED BELOW GROUND. 20 Access
16、ed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 AS/NZS 4791:2006 4 COPYRIGHT STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND Australian/New Zealand Standard Hot-dip galvanized (zinc) coatings on ferrous open sections, applied by an in-line process 1 SCOPE This Standard specifies requirements for the ma
17、ss, quality and testing of galvanized coatings applied to ferrous open sections on all surfaces, using an in-line process that utilizes specialized equipment. Matters relating to the quality, properties, or dimensional requirements of the open sections are outside the scope of this Standard. NOTES:
18、1 Advice and recommendations on information to be supplied by the purchaser to the hot-dip galvanizer at the time of enquiry or order are contained in the purchasing guidelines set out in Appendix A. 2 Alternative means for determining compliance with this Standard are given in Appendix B. 3 General
19、 information on factors that affect the corrosion of galvanized steel is given in Appendix C. 4 For guidance on duplex protection systems below ground refer to Appendix G. 5 Electroplated zinc coatings applied to steel strip for manufacture into open sections are not covered by this Standard. The ap
20、plication of this Standard to these coatings is subject to agreement between the purchaser and the supplier. 2 REFERENCED DOCUMENTS The following documents are referred to in this Standard: AS 1199 Sampling procedures for inspection by attributes 1199.0 Part 0: Introduction to the ISO 2859 attribute
21、 sampling system 1199.1 Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection 2331 Methods of test for metallic and related coatings 2331.1.3 Method 1.3: Local thickness testsMagnetic method 2331.1.4 Method 1.4: Local thickness testsMagnetic induction and eddy
22、current methods 2331.2.1 Method 2.1: Tests for average coating mass per unit area or for thickness Dissolution methods Strip and weigh, and analytical 2331.2.3 Method 2.3: Tests for average coating mass per unit area or for thickness Hydrogen evolution method for zinc coatings 2331.3.1 Method 3:1: C
23、orrosion and related property testsNeutral salt spray (NSS) test 2505 Metallic materials 2505.1 Method 1: Sheet, strip and plateBend tests 2706 Numerical valuesRounding and interpretation of limiting values AS/NZS 2243 Safety in laboratories 2243.1 Part 1: Planning and operational aspects Accessed b
24、y UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 5 AS/NZS 4791:2006 COPYRIGHT 2243.2 Part 2: Chemical aspects AS/NZS 2312 Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings 3750 Paints for steel structures 3750.9 Part 9: Organic zinc-rich primer
25、 3750.15 Part 15: Inorganic zinc silicate paint AS/NZS ISO 9001 Quality management systemsRequirements 9004 Quality management systemsGuidelines for performance improvements HB 18.28 Conformity assessmentGuidance on a third party certification system for products SANZ HB 18.28 Guide 28General rules
26、for a model third-party certification system for products ISO 2063 Thermal sprayMetallic and other inorganic coatingsZinc, aluminium and their alloys 3 DEFINITIONS For the purpose of this Standard, the definitions below apply. 3.1 Coating mass The total mass of hot-dip galvanized coating, on a singl
27、e surface, expressed in grams per square metre. 3.2 Coating thickness The total thickness of hot-dip galvanized coating, on a single surface, expressed in micrometres. 3.3 Coating thickness, local The coating thickness at a reference area. 3.4 Galvanizer A person, persons or organization responsible
28、 for the coating of the product with molten zinc. 3.5 Hot-dip galvanized coating A coating consisting of zinc-iron alloys covered by zinc, obtained by the in-line hot-dip galvanizing process. NOTE: The term hot-dip galvanized coating is subsequently referred to as the coating. 3.6 Hot-dip galvanizin
29、g A process comprising pretreatment, and molten zinc baths in which steel products are dipped so as to form adherent zinc and zinc-iron alloy coatings. 3.7 In-line hot-dip galvanizing An in-line process using specialized equipment, comprising pretreatment and molten zinc baths through which steel pr
30、oducts are continuously passed so as to form an adherent zinc and zinc-iron alloy coating. NOTE: During the continuous in-line galvanizing process a uniform, smooth finish is achieved by removing the excess coating by mechanical or other means. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 200
31、8 AS/NZS 4791:2006 6 COPYRIGHT 3.8 Open section A section produced by cold forming carbon or low alloy steel sheet, strip, plate or bar, e.g. angles, channels and flats. 3.9 Reference area The area within which a specific number of single measurements is required to be made. 3.10 Significant surface
32、 The part of the open section to be covered by the coating and which is essential for serviceability and/or appearance. 3.11 Supplier A person, persons or organization responsible for the supply of the galvanized product. 4 GALVANIZING PROCESS 4.1 Pretreatment Open sections shall be adequately prepa
33、red for galvanizing by a suitable process. 4.2 Bath composition The molten metal in the working area of the galvanizing bath shall contain not less than 98.0% by mass of zinc. 4.3 Galvanizing Open sections are galvanized using an in-line process. On withdrawal from the bath any excess zinc in the co
34、ating may be removed by an appropriate means. 4.4 Treatment after galvanizing A short- or long-term barrier coat (a conversion coating and/or a clear organic coat) may be applied immediately after galvanizing. 5 APPEARANCE AND FREEDOM FROM DEFECTS The zinc coating shall be continuous, smooth and as
35、evenly distributed as practicable, and be free of defects that are detrimental to the stated use of the open section. The colour of galvanized open sections could change to dull grey with ageing. Provided that other requirements of this Standard are met, the colour shall not be a cause for rejection
36、. Coatings which are damaged at the time of installation or after installation shall be repaired in compliance with Appendix D. NOTES: 1 Where a superior finish is required or the presence, size or frequency of any defect in the coating is considered to be of concern, appropriate arrangements should
37、 be made between the purchaser and the galvanizer or supplier of the open section product. This may be achieved by the provision of acceptable type samples or methods of test, or by reference to significant surfaces. 2 Advice on the transport and storage of open sections is given in Appendix E. 3 It
38、 is normal practice for these products to be cut to length after being coated, thus leaving the cut ends uncoated. 4 Wet storage stain (white or dark corrosion products primarily of basic zinc oxide, formed during storage in humid conditions after hot-dip galvanizing), which occurs after the product
39、 leaves the galvanizers factory, is not a cause for rejection. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 7 AS/NZS 4791:2006 COPYRIGHT 6 DESIGNATION The designation for in-line galvanized coatings shall comprise the number of this Standard, i.e. AS/NZS 4791, followed by the coating cla
40、ss, i.e. the letters ILG (in-line galvanized) and a two or three digit number representing the specified minimum average zinc coating mass, in grams per square metre. Example of designation: AS/NZS 4791 ILG100. 7 SELECTION OF TEST SPECIMENS 7.1 For coating mass or thickness determinations Where the
41、gravimetric method or the volumetric method is used to determine the coating mass (see Appendix F), one specimen at least 50 mm long shall be cut from a sample representing the total product. Where the magnetic, magnetic induction or the eddy current method is used for local thickness measurements (
42、see Appendix F), a suitable test sample shall be selected. 7.2 For adherence of the coating The test specimen for the adherence of coating test shall be selected from a sample of flat- section product and shall be a minimum of 50 mm wide. (See Clause 9, Notes 1 and 3). 8 COATING MASS AND THICKNESS 8
43、.1 Coating mass The coating mass shall be determined either by the gravimetric method or the volumetric method in accordance with Appendix F, Paragraph F2 or F3 respectively. The coating mass on significant surfaces shall comply with the relevant requirements of Table 1. 8.2 Coating thickness Coatin
44、g thickness may be determined for information, in accordance with Appendix F, Paragraph F4, and should be not less than the values given in Table 1. When open sections are tested by the magnetic method, the local coating thickness is the average of 10 determinations performed randomly over an area o
45、f 20 cm2 (the reference area). The average thickness is the mean of the values taken from three separate test areas (i.e. the mean of 30 determinations). Unless otherwise specified, thickness measurements shall be carried out at positions not less than 10 mm away from the ends or edges of an open se
46、ction. Accessed by UNIVERSITY OF SOUTH AUSTRALIA on 02 Apr 2008 AS/NZS 4791:2006 8 COPYRIGHT TABLE 1 COATING MASS REQUIREMENTS Average coating mass Approximate minimum coating thickness, m Coating class g/m2 min. Local Average ILG75 75 8 11 ILG100* 100 11 14 ILG125 125 14 18 ILG150 150 17 21 ILG175
47、175 20 25 ILG200 200 22 28 ILG250 250 28 35 ILG300* 300 34 42 * Indicates coating class commercially available. NOTES: 1 1 g/m2 coating mass 0.14 m coating thickness. 2 Classes other than those indicated may not be commercially available, see supplier. 9 ADHERENCE OF COATING The coating shall be suf
48、ficiently adherent to withstand normal handling conditions without peeling or flaking. Each test specimen representing a flat-section product, shall be tested in accordance with AS 2505.1. Both surfaces of the specimen shall withstand a bend of 180 around a mandrel of the appropriate diameter specif
49、ied in Table 2, without flaking of the coating. Failure of the coating within 5 mm of the edge of the test specimen shall be disregarded. NOTES: 1 The direction of testing is not significant but the test should be performed on a longitudinal test piece (i.e. with the axis of bend at right angles to the rolling direction) to reduce the incidence of base steel failure. 2 Because of the nature of the zinc/iron alloy, some powdering of the coating may occur on the inside of the bend. 3 Adhesion tests