Hot-Dip Galvanized Fasteners
Hot-dip galvanizing dips the part in molten zinc for a thick, durable coating for outdoor carbon-steel fasteners. The coating is thick enough that nuts must be tapped oversize.
HDG facts
| Typical thickness | About 50 micrometres (2 mils) minimum average |
|---|---|
| Nuts | Tapped oversize after galvanizing and lubricated |
| Structural | A325 may be galvanized; A490 may not |
| Mixing | Do not pair an HDG bolt with a plain or plated nut |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
ASTM F2329 · ISO 10684 · hot-dip galvanized fasteners
FIELD IDENTIFICATION
What it is
Hot-dip galvanizing dips the part in molten zinc for a thick, durable coating for outdoor carbon-steel
fasteners. The coating is thick enough that nuts must be tapped oversize.
HOT-DIP GALV
Dull gray, thick coating; use oversize-tapped
nuts
HDG facts
Typical thickness
About 50 micrometres (2 mils) minimum average
Nuts
Tapped oversize after galvanizing and lubricated
Structural
A325 may be galvanized; A490 may not
Mixing
Do not pair an HDG bolt with a plain or plated nut
Key points
Lubrication changes the torque K factor; use the manufacturer or RCSC procedure.
Governing standards: ASTM F2329/F2329M-15(2023); ISO 10684:2004; ASTM A563/A563M-26. Editions shown are the latest confirmed as of September 2026. The drawing and the
governing standard always take precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-2C50F5 · thefastenerapp.com/fastener-guide/technical-reference/hot-dip-galvanized-fasteners · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
