ASTM A123 A123M-2008 Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products.pdf

1、Designation: A 123/A 123M 08Standard Specification forZinc (Hot-Dip Galvanized) Coatings on Iron and SteelProducts1This standard is issued under the fixed designationA 123/A 123M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the

2、 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 reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This specification covers th

3、e requirements for zinccoating (galvanizing) by the hot-dip process on iron and steelproducts made from rolled pressed and forged shapes, castings,plates, bars, and strips.1.2 This specification covers both unfabricated products andfabricated products, for example, assembled steel products,structura

4、l steel fabrications, large tubes already bent or weldedbefore galvanizing, and wire work fabricated from uncoatedsteel wire. This specification also covers steel forgings and ironcastings incorporated into pieces fabricated before galvanizingor which are too large to be centrifuged (or otherwise ha

5、ndledto remove excess galvanizing bath metal).NOTE 1This specification covers those products previously addressedin Specifications A 123-78 and A 386-78.1.3 This specification does not apply to wire, pipe, tube, orsteel sheet which is galvanized on specialized or continuouslines, or to steel less th

6、an 22 gage (0.0299 in.) 0.76 mm thick.1.4 The galvanizing of hardware items that are to becentrifuged or otherwise handled to remove excess zinc (suchas bolts and similar threaded fasteners, castings and rolled,pressed and forged items) shall be in accordance with Speci-fication A 153/A 153M.1.5 Fab

7、ricated reinforcing steel bar assemblies are coveredby the present specification. The galvanizing of separatereinforcing steel bars shall be in accordance with SpecificationA 767/A 767M.1.6 This specification is applicable to orders in eitherinch-pound units (as A 123) or SI units (as A 123M). Inch-

8、pound units and SI units are not necessarily exact equivalents.Within the text of this specification and where appropriate, SIunits are shown in parentheses. Each system shall be usedindependently of the other without combining values in anyway. In the case of orders in SI units, all testing and ins

9、pectionshall be done using the metric equivalent of the test orinspection method as appropriate. In the case of orders in SIunits, such shall be stated to the galvanizer when the order isplaced.2. Referenced Documents2.1 ASTM Standards:2A 47/A 47M Specification for Ferritic Malleable Iron Cast-ingsA

10、 90/A 90M Test Method for Weight Mass of Coating onIron and Steel Articles with Zinc or Zinc-Alloy CoatingsA 143/A 143M Practice for Safeguarding Against Em-brittlement of Hot-Dip Galvanized Structural Steel Prod-ucts and Procedure for Detecting EmbrittlementA 153/A 153M Specification for Zinc Coati

11、ng (Hot-Dip) onIron and Steel HardwareA 384/A 384M Practice for Safeguarding Against Warpageand Distortion During Hot-Dip Galvanizing of Steel As-sembliesA 385 Practice for Providing High-Quality Zinc Coatings(Hot-Dip)A 767/A 767M Specification for Zinc-Coated (Galvanized)Steel Bars for Concrete Rei

12、nforcementA 780 Practice for Repair of Damaged and Uncoated Areasof Hot-Dip Galvanized CoatingsA 902 Terminology Relating to Metallic Coated Steel Prod-uctsB6 Specification for ZincB 487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB 602

13、 Test Method for Attribute Sampling of Metallic andInorganic CoatingsE 376 Practice for Measuring Coating Thickness byMagnetic-Field or Eddy-Current (Electromagnetic) Exami-nation Methods1This specification is under the jurisdiction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products and

14、 is the direct responsibility ofSubcommittee A05.13 on Structural Shapes and Hardware Specifications.Current edition approved July 1, 2008. Published August 2008. Originallyapproved in 1928. Last previous edition approved in 2002 as A 123/A 123M - 02.2For referenced ASTM standards, visit the ASTM we

15、bsite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United St

16、ates.3. Terminology (See Fig. 1)3.1 Definitions:3.1.1 The following terms and definitions are specific to thisspecification. Terminology A 902 contains other terms anddefinitions relating to metallic-coated steel products.3.2 Definitions of Terms Specific to This Standard:3.2.1 average coating thick

17、ness, nthe average of threespecimen coating thicknesses.3.2.2 black, adjdenotes the condition of not galvanized orotherwise coated. For purposes of this specification the word“black” does not refer to the color or condition of surface, or toa surface deposit or contamination.3.2.3 coating thickness

18、grade, nthe numerical value fromTable 1 at the intersection of a material category and athickness range.3.2.4 gross dross inclusions, nthe iron/zinc intermetallicspresent in a galvanized coating in a form other than finelydispersed pimples.3.2.4.1 DiscussionThese inclusions would create an ex-posed

19、steel spot if they were removed from the coating. TheseFIG. 1 Single- and Multi-Specimen ArticlesA 123/A 123M 082inclusions are raised surfaces and are easily knocked offthrough contact with lifting straps or chains, tools, fixtures, orother galvanized parts.3.2.5 material category, nthe general cla

20、ss or type ofmaterial or process of manufacture, or both, that nominallydescribes a unit of product, or from which a unit of product ismade. For example, bar grating belongs to the category “strip,”handrail belongs to the category “pipe,” etc.3.2.6 multi-specimen article, na unit of product whosesur

21、face area is greater than 160 in.2100 000 mm2. Forthickness testing purposes, articles whose surface area isgreater than 160 in.2are subdivided into three continuous localsections, nominally equal in surface area, each of whichconstitutes a specimen. In the case of any such local sectioncontaining m

22、ore than one material category or steel thicknessrange as delineated in Table 1, that section will contain morethan one specimen (see Fig. 1).3.2.7 sample, na collection of individual units of productfrom a single lot selected in accordance with Section 7, andintended to represent that lot for accep

23、tance. If a sample istaken as representing the lot for acceptance, the sample shall betaken at random from the lot without regard to the perceivedquality or appearance of any individual unit in the lot beingsampled. The sample consists of one or more test articles.3.2.8 single-specimen article, na u

24、nit of product whosesurface area is equal to or less than 160 in.2100 000 mm2orthat is centrifuged or otherwise similarly handled in thegalvanizing process to remove excess galvanizing bath metal(free zinc). For thickness testing purposes, the entire surfacearea of each unit of product constitutes a

25、 specimen. In the caseof any such article containing more than one material categoryor steel thickness range as delineated in Table 1, that articlewill contain more than one specimen (see Fig. 1).3.2.9 specimen, nthe surface of an individual test articleor a portion of a test article, upon which thi

26、ckness measure-ments are to be performed, which is a member of a lot, or amember of a sample representing that lot. For magneticthickness measurements, specimen excludes any area of thesurface which is subject to processes (such as flame cutting,machining, threading, etc.) that can be expected to re

27、sult insurface conditions not representative of the general surfacecondition of the test article, or is disqualified by the measure-ment method. The minimum average coating thickness gradefor any specimen shall be one coating grade below thatrequired for the appropriate material category and thickne

28、ss inTable 1. For a unit of product whose surface area is equal to orless than 160 in.2100 000 mm2, the entire surface area ofeach test article constitutes a specimen. In the case of an articlecontaining more than one material category or steel thicknessrange as delineated in Table 1, that article w

29、ill contain morethan one specimen, as appropriate (see Fig. 1).3.2.10 specimen coating thickness, nthe average thick-ness from no less than five test measurements on a specimen,when each measurement location is selected to provide thewidest dispersion (in all applicable directions) of locations fort

30、he steel category of the test article within the confines of thespecimen volume.3.2.11 test article, nan individual unit of product that is amember of the sample and that is examined for conformance toa part of this specification.4. Ordering Information4.1 Orders for coatings provided under this spe

31、cificationshall include the following:4.1.1 Quantity (number of pieces to be galvanized) and totalweight.4.1.2 Description (type and size of products) and weight.4.1.3 ASTM specification designation and year of issue.4.1.4 Material identification (see 5.1) and surface conditionor contamination.4.1.5

32、 Sampling plan, if different from 7.3.4.1.6 Special test requirements (see 8.1).4.1.7 Special requirements (special stacking, heavier coat-ing weight, etc.).4.1.8 Tagging or piece identification method.5. Materials and Manufacture5.1 Steel or IronThe specification, grade, or designationand type and

33、degree of surface contamination of the iron orsteel in articles to be galvanized shall be supplied by thepurchaser to the hot-dip galvanizer prior to galvanizing.NOTE 2The presence in steels and weld metal, in certain percentages,of some elements such as silicon, carbon, and phosphorus tends toaccel

34、erate the growth of the zinc-iron alloy layer so that the coating mayhave a matte finish with little or no outer zinc layer. The galvanizer hasonly limited control over this condition. The mass, shape, and amount ofcold working of the product being galvanized may also affect thiscondition. Practice

35、A 385 provides guidance on steel selection anddiscusses the effects of various elements in steel compositions (forexample, silicon), that influence coating weight and appearance.5.2 FabricationThe design and fabrication of the productto be galvanized are the responsibilities of the designer and thef

36、abricator. PracticesA 143,A 384, andA 385 provide guidancefor steel fabrication for optimum hot dip galvanizing and shallbe complied with in both design and fabrication. ConsultationTABLE 1 Minimum Average Coating Thickness Grade by Material CategoryMaterial CategoryAll Specimens TestedSteel Thickne

37、ss Range (Measured), in. (mm)316 to 4.8 to 6.4) $14 ($6.4)Structural Shapes and Plate 45 65 75 85 100Strip and Bar 45 65 75 85 100Pipe and Tubing 45 45 75 75 75Wire 35 50 60 65 80Reinforcing Bar . . . . 100A 123/A 123M 083between the designer, fabricator, and galvanizer at appropriatestages in the d

38、esign and fabrication process will reduce futureproblems.5.3 CastingsThe composition and heat treatment of ironand steel castings shall conform to specifications designated bythe purchaser. Some types of castings have been known toshow potential problems with predisposition to being em-brittled duri

39、ng the normal thermal cycle of hot-dip galvanizing.It is the responsibility of the purchaser to heat treat orotherwise allow for the possibility of such embrittling phenom-ena. The requirements for malleable iron castings to begalvanized shall be as stated in Specification A 47.5.4 ZincThe zinc used

40、 in the galvanizing bath shallconform to Specification B6. If a zinc alloy is used as theprimary feed to the galvanizing bath, then the base materialused to make that alloy shall conform to Specification B6.5.5 Bath CompositionThe molten metal in the workingvolume of the galvanizing bath shall conta

41、in not less than anaverage value of 98.0 % zinc by weight.NOTE 3The galvanizer may choose to add trace amounts of certainelements (for example, aluminum, nickel, and tin) to the zinc bath to helpin the processing of certain reactive steels or to enhance the cosmeticappearance of the finished product

42、. The use of these trace elements ispermitted provided that the bulk chemistry of the galvanizing bath is atleast 98.0 % zinc by weight. The elements can be added to the galvanizingbath as part of a pre-alloyed zinc feed, or they can be added to the bath bythe galvanizer using a master feed alloy.6.

43、 Coating Properties6.1 Coating ThicknessThe average thickness of coatingfor all specimens tested shall conform to the requirements ofTable 1 for the categories and thicknesses of the material beinggalvanized. Minimum average thickness of coating for anyindividual specimen is one coating grade less t

44、han that requiredin Table 1. Where products consisting of various materialthicknesses or categories are galvanized, the coating thicknessgrades for each thickness range and material category ofmaterial shall be as shown in Table 1. In the case of orders inSI units, the values in Table 1, shall be ap

45、plicable as metricunits in micrometres. In the case of orders in inch-pound units,the measured value shall be converted to coating grade units bythe use of Table 2. The specification of coating thicknessesheavier than those required by Table 1 shall be subject tomutual agreement between the galvaniz

46、er and the purchaser.(Fig. 2 is a graphic representation of the sampling andspecimen delineation steps, and Fig. 3 is a graphic representa-tion of the coating thickness inspection steps.)6.1.1 For articles whose surface area is greater than 160in.2100 000 mm2 (multi-specimen articles), each test art

47、iclein the sample must meet the appropriate minimum averagecoating thickness grade requirements of Table 1, and eachspecimen coating thickness grade comprising that overallaverage for each test article shall average not less than onecoating grade below that required in Table 1.6.1.2 For articles who

48、se surface area is equal to or less than160 in.2100 000 mm2 (single-specimen articles), the averageof all test articles in the sample must meet the appropriateminimum average coating thickness grade requirements ofTable 1, and for each test article, its specimen coating thicknessshall be not less th

49、an one coating grade below that required inTable 1.6.1.3 No individual measurement, or cluster of measure-ments at the same general location, on a test specimen shall because for rejection under the coating thickness requirements ofthis specification provided that when those measurements areaveraged with the other dispersed measurements to determinethe specimen coating thickness grade for that specimen, therequirements of 6.1.1 or 6.1.2, as appropriate are met.NOTE 4The coating thickness grades in Table 1 represent the mini-mum value obtainable