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Galvanizing Standards

Specifications for hot-dip galvanizing

There are certain specifications that have been developed for hot-dip galvanizing in order to produce a high-quality coating. There are three main standards that govern hot-dip galvanized steel, and a handful of supporting specifications that design engineers and fabricators should become familiar with to promote a high-quality coating and ensure their steel design is suitable for hot-dip galvanizing.

ASTM Standards

The three governing ASTM specifications for hot-dip galvanizing are:

  • ASTM A123/A123M: Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products
    • Single pieces of steel or fabrications with different types of steel products
  • ASTM A153/A153M: Standard Specification for Zinc Coating (Hot-Dip) on Iron and Hardware
    • Fasteners and small products that are centrifuged after galvanizing to remove excess zinc
  • ASTM A767/A767M: Standard Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement
    • Reinforcing steel or rebar

Other Galvanizing Standards

There are also a few international governing standards to be aware of:

  • CSA G164: Hot-Dip Galvanizing of Irregularly Shaped Article (Note: The scope of this standard was revised in 2018 to include products intended or primarily for use in electrical and communication systems only.)
  • ISO 1461: Hot-Dip Galvanized Coatings on Fabricated Iron and Steel Assemblies Specifications and Test Methods
  • AASHTO M111 (ASTM A123): Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products
    AASHTO M232 (ASTM A153): Zinc Coating (Hot-Dip) on Iron and Steel Hardware

In addition to the governing standards, there are a handful of pre- and post-galvanizing supporting specifications that a specifier/designer should also be familiar with:

Pre-Galvanizing

  • ASTM A143/A143M: Standard Practice for Safeguarding Against Embrittlement of Hot-Dip Galvanized Structural Steel Products and Procedure for Detecting Embrittlement
  • ASTM A384/A384M: Standard Practice for Safeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies
  • ASTM A385/A385M: Standard Practice for Providing High-Quality Zinc Coatings (Hot-Dip)
  • ASTM B6: Standard Specification for Zinc

Post-Galvanizing

  • ASTM A780: Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings
  • ASTM D6386: Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Paint
  • ASTM D7803: Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Powder Coating
  • ASTM E376: Standard Practice for Measuring Coating Thickness by Magnetic-Field or Eddy-Current (Electromagnetic) Examination Methods

Let's examine a few of these specifications in more detail.