international zinc association

International Zinc Association


How to Successfully Galvanize per ASTM A123

AMEGAC GalvaForum 2021 VirtualInternational Zinc Association

Bernardo Duran


Fair Use Copyright

• Purpose: Non-commercial educational presentation for a not-for-profit trade association.

• Nature of Copyrighted Works: Written publication. ASTM Standard A123, 2017, "Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products," ASTM International, West Conshohocken, PA, DOI: 10.1520/A0123_A0123M-17, www.astm.org.

• Portion of Copyrighted Works Used: brief excerpts or paraphrased sections from written publications; tables of coating thickness information

• Effect Upon the Potential Market of Copyrighted Works: none expected

• Transformative Value: Using the above copyrighted work combined with my own perspective and experience, I will teach how to comply with the requirements of the standard specification.


Objective

• Discuss the requirements of ASTM A123 and

how to comply with them.


Full Standard Title

• ASTM A123/A123M - 17

– Standard Specification for Zinc (Hot-Dip Galvanized)

Coatings on Iron and Steel Products

• Notes:

– Inch-pound units (A123)

– SI or metric units (A123M)

– The ‘- 17’ indicates the revision year, which is

2017 in this case.


ASTM A123 Sections

1. Scope – What this document does and does not cover.

2. Referenced Documents – Lists all the ASTM standards referenced in A123.

3. Terminology – Includes definitions specific to this standard and minimum average coating thickness by material category.

4. Ordering Information – Lists items that would be important for purchase and sales documents, and specific and special requirements.

5. Materials and Manufacture – Describes the materials to be galvanized, references to other standards for their fabrication, and zinc and galvanizing bath composition requirements.


ASTM A123 Sections

6. Coating Properties – Discusses requirements related to coating thickness, finish, threaded components, appearance, and adherence.

7. Sampling – Outlines the minimum number of test articles required for each lot of material.

8. Test Methods – Describes the different test requirements and methods.

9. Inspection, Rejection, and Retest – Lists who is to inspect the material and the location for such inspections.

10. Certification – Discusses the requirement for furnishing documentation the material has been inspected and the requirements have been met.

11. Keywords – Lists words commonly used related to this standard (e.g., galvanized coatings; zinc coatings)


ASTM A123 – Scope

Covers:

• The batch hot-dip galvanizing process on iron and

steel products (rolled pressed, forged shapes,

castings, plates, bars, strips).

• Fabricated and unfabricated products.

• Reinforcing bar (rebar) welded to a fabrication

galvanized per this specification.


ASTM A123 – Scope

Does not cover:

• Items galvanized and then centrifuged after

galvanizing. (Galvanized per ASTM A153.)

• Single rebar. (Galvanized per ASTM A767 or

A1094)

• Continuously galvanized wire, pipe, tube, or steel

sheet.

• Steel less than 22 gage thick.


ASTM A123 Requirements

• Coating Thickness

• Finish

• Appearance

• Adherence

• Embrittlement (lack of)


ASTM A123 – Coating Thickness Grade

• The Coating Thickness Grade (Table 1) is

determined by the intersection of:

1. Material Category

2. Steel Thickness Range


ASTM A123 – Table 1

Material

Category

All Specimens Tested

Steel Thickness Range (Measured), in. [mm]

< 1/16

[<1.6]

≥1/16 to < 1/8

[≥ 1.6 to < 3.2]

≥1/8 to < 3/16

[≥ 3.2 to 4.8]

≥3/16 to < ¼

[≥ 4.8 to < 6.4]

≥1/4 to < 5/8

[≥ 6.4 to < 16.0]

≥ 5/8

[≥ 16.0]

Structural Shapes 45 65 75 75 100 100

Strip & Bar 45 65 75 75 75 100

Plate 45 65 75 75 75 100

Pipe & Tubing 45 45 75 75 75 75

Wire 35 50 60 65 80 80

Reinforcing Bar -- -- -- -- 100 100


ASTM A123 – Coating Thickness

• After determining the Coating Thickness Grade in

Table 1, then use Table 2 to convert it to a coating

thickness (mils or µm) or coating weight (oz/ft2 or

g/m2).

• In A123, beneath Table 2 you will find coating

thickness conversions (e.g., mils to microns or vice

versa).



Coating Thickness Grade*

Coating Grade mils oz/ft2 µm g/m2

35 1.4 0.8 35 245

45 1.8 1.0 45 320

50 2.0 1.2 50 355

55 2.2 1.3 55 390

60 2.4 1.4 60 425

65 2.6 1.5 65 460

75 3.0 1.7 75 530

80 3.1 1.9 80 565

85 3.3 2.0 85 600

100 3.9 2.3 100 705


ASTM A123 – Test Articles

• Test Article: An individual unit of product examined for conformance to this specification.

• Types of Test Articles:1. Single-Specimen (surface area equal to or less than 160 in2

or 100,000 mm2)

2. Multi-Specimen (surface area greater than 160 in2

or 100,000 mm2)

• Specimen: The surface of an individual test article or portion of it upon which thickness measurements are to be taken.


ASTM A123 – Test Articles• The number of pieces in a lot determines the required number of test

articles.

• For example, if there are 501 to 1,200 pieces in a lot, 5 test articles are

required.

Number of Pieces in Lot Number of Test

Articles

3 or less all

(excluded to maintain copyright)

501 to 1,200 5


3,201 to 10,000 13



ASTM A123 – Test Articles• Single-Specimen

Test Article: A product

whose surface area is

equal to or less than 160

in2.

• For single-specimen test

articles, the whole test

article will be only one

specimen.

• Example: Small angles

(prior to galvanizing).


ASTM A123 – Test Articles• Multi-Specimen Article: A product whose surface area is

greater than 160 in2.

• Will have three specimens, which are three evenly divided

areas on the test article. (Note: If the article has more than

one material category or steel thickness, there will be more

than three specimens.)


ASTM A123 – Coating Thickness Requirement

• For each specimen, at least 5 widely dispersed coating thickness measurements are required.

• No individual measurement or cluster of measurements is cause for rejection. (No bare spots allowed.)

• Do not take coating thickness measurements near edges or on areas subject to processes not representative of the general surface condition (flame cutting, machining, etc.).


ASTM A123 – Coating Thickness Requirement

• The average of all the test articles must meet the coating thickness grade requirement of Table 1 (next slide).

• For an individual specimen, the coating thickness grade must be one grade less than that required in Table 1 or thicker.

• For one multi-specimen test article, the average of all three specimens must meet the coating thickness grade requirement of Table 1.



Material

Category

All Specimens Tested

Steel Thickness Range (Measured), in. [mm]

< 1/16

[<1.6]

≥1/16 to < 1/8

[≥ 1.6 to < 3.2]

≥1/8 to < 3/16

[≥ 3.2 to 4.8]

≥3/16 to < ¼

[≥ 4.8 to < 6.4]

≥1/4 to < 5/8

[≥ 6.4 to < 16.0]

≥ 5/8

[≥ 16.0]

Structural Shapes 45 65 75 75 100 100

Strip & Bar 45 65 75 75 75 100

Plate 45 65 75 75 75 100

Pipe & Tubing 45 45 75 75 75 75

Wire 35 50 60 65 80 80

Reinforcing Bar -- -- -- -- 100 100


ASTM A123 – Additional Coating Measurement Methods

• Stripping Method

• Weighing Before and After Galvanizing

• Microscopy (destructive)


ASTM A123 – Finish

• The coating shall be continuous, reasonably smooth, and uniform in thickness, as allowed by the weight, shape, and necessary handling of the product.

• Minor roughness that does not interfere with the intended use of the product is not rejectable. Minor roughness due to steel chemistry or the as-received condition of the steel is not rejectable.



• Rejection for excess coating thickness shall be

made only if it interferes with the intended use of

the product or presents a safety hazard (such as

edge spikes).

• Threaded areas on components shall comply with

the requirements of ASTM A153/A153M –

Standard Specification for Zinc Coating (Hot-Dip)

on Iron and Steel Hardware.



• The galvanizer and purchaser shall agree on surface roughness and smoothing guidelines for items to be painted or powder coated after galvanizing.

• Further cleaning, profiling, and outgassing shall comply with ASTM D6386 or D7803 and are the responsibility of the painter or powder coater.


ASTM A123 – Appearance

• Galvanized articles shall be free from uncoated areas, blisters, flux deposits, and gross dross inclusions.

• Gross Dross Inclusions: the iron/zinc intermetallics present in a galvanized coating in a form other than finely dispersed pimples.

• Lumps or other heavy deposits of zinc that will interfere with the intended use of the product are not permitted.


ASTM A123 – Appearance

• Plain (unthreaded) holes ½ inch in diameter or

greater shall reasonably free of excess zinc. The

galvanizer is responsible for cleaning these holes.

• Touch marks and handling marks are permitted if

bare spots are not present.


ASTM A123 – Adhesion Testing

• Only necessary when there is evidence of an adhesion concern.

• To conduct adhesion testing, apply “considerable pressure in a manner tending to remove a portion of the coating” using a stout knife. Use the point of the knife to cut or pry at the coating.

• Adhesion is inadequate (fails) if the zinc coating flakes off in a layer and exposes the base metal.

• Do not conduct adhesion testing at edges or corners, which are points of lowest coating adhesion. Do not use removal of small particles of zinc coating by whittling to determine adhesion failure.


ASTM A123 – Adhesion Testing


ASTM A123 – Embrittlement Testing

• Embrittlement testing is only required when there

is strong evidence of its present.

• Conduct embrittlement testing in accordance with

ASTM A143/A143M – Practice for Safeguarding

Against Embrittlement of Hot-Dip Galvanized

Structural Steel Products and Procedure for

Detecting Embrittlement.


ASTM A123 – Touch-Up

• The total area needing touch-up shall be no

more than ½ of 1% of the accessible

surface area, or 36 square inches per ton of

piece weight, whichever is less.

• Bare areas shall be touched-up per ASTM

A780/A780M.


ASTM A123 – Touch-Up• Each area needing touch-up shall be 1 inch or less in its narrowest

dimension. (This means an area can be longer than 1 inch, but it

cannot also be wider than 1 inch at the same time.)

Bare Spot ½” wide x 16” long. Therefore acceptable.

Bare Spot 6” wide x 4” long. Therefore rejectable.


ASTM A123 – Touch-Up

• When areas needing touch-up exceed the maximum allowances, or are on inaccessible areas (inside pipes, tubes, tanks, etc.), the part shall be rejected.

• The thickness of touch-up with zinc solder or metalizing shall match the coating grade as specified in Table 1.

• The thickness of touch-up with zinc-rich paint shall be 50% thicker than that required by Table 1, but not thicker than 4.0 mils.


Remaining Sections

9. Inspection, Rejection, and Retest – Lists who is to inspect the material and the location for such inspections.

• The galvanizer is responsible for having an in-plant inspection program and complying with the requirements of ASTM A123.

• The purchaser accepts or rejects the material based on the inspection by the galvanizer, and they can also perform the inspection themselves or hire a third party.

• The galvanizer shall inspect the material at their plant before shipment. When agreed upon beforehand, the purchaser can perform additional inspections offsite, which would govern acceptance or rejection.


Remaining Sections

10. Certification – Discusses the requirement for furnishing documentation the material has been inspected and the requirements have been met.

• Typically there is nominal fee for this service, and it is usually a simple written document. The inspection sheets can be included with the certification, but that is not necessary unless requested by the purchaser.


Related ASTM Standards

• A143/A143M Standard Practice for Safeguarding Against Embrittlement of Hot-Dip Galvanized Structural Steel Products and Procedure for Detecting Embrittlement

• A153/A153M Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware

• A384/A384M Standard Practice for Safeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies

• A385/A385M Standard Practice for Providing High-Quality Zinc Coatings (Hot-Dip)


Related ASTM Standards

• ASTM A767 / A767M Standard Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement

• A780/A780M Standard Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings

• ASTM A1094 / A1094M Standard Specification for Continuous Hot-Dip Galvanized Steel Bars for Concrete Reinforcement

• ASTM B6 Standard Specification for Zinc

• ASTM D6386 Standard Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Painting


Additional Study

• https://www.astm.org/Standards/A123.htm

• Read ASTM A123 and other standards frequently. This makes the process of learning the documents easier.

• American Galvanizers Association (AGA) Publication Inspection of Hot-Dip Galvanized Steel Products.

• Free AGA Inspection App (search for ‘galvanizing inspection’ on Google and Apple stores).


Questions?