ASTM F3125 Grade A325
A325 is the standard high-strength structural bolt for steel connections in buildings and bridges. Since 2015 it is a grade within ASTM F3125, not a standalone specification.
| Head | Heavy hex, short thread length |
|---|---|
| Marking | A325 plus maker ID. Underlined A325 = Type 3 weathering |
| Nut | ASTM A563 heavy hex, grade per F3125 (DH for galvanized) |
| Washer | ASTM F436 where required by RCSC |
| Installation | RCSC / AISC methods, not a machinery torque chart |
Mechanical properties (F3125 Grade A325)
| Size | Proof | Yield (min) | Tensile (min) | Hardness |
|---|---|---|---|---|
| 1/2 to 1-1/2 in | 85 ksi | 92 ksi | 120 ksi | C25 - C34 |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
ASTM F3125 / F3125M · Grade A325 · structural bolt
What it is
FIELD IDENTIFICATION
A325 is the standard high-strength structural bolt for steel connections in buildings and bridges. Since
2015 it is a grade within ASTM F3125, not a standalone specification.
MFG
A325
Heavy hex head, short thread; stamped A325 +
maker
Head
Heavy hex, short thread length
Marking
A325 plus maker ID. Underlined A325 = Type 3 weathering
Nut
ASTM A563 heavy hex, grade per F3125 (DH for galvanized)
Washer
ASTM F436 where required by RCSC
Installation
RCSC / AISC methods, not a machinery torque chart
Mechanical properties (F3125 Grade A325)
Size
1/2 to 1-1/2 in
Proof
Yield (min)
85 ksi
Tensile (min)
92 ksi
Hardness
120 ksi
C25 - C34
Key points
A structural bolt is sold and installed as an assembly: bolt, nut and washer from compatible lots.
Galvanized A325 requires a nut that is overtapped and lubricated, and must be installed as a matched set.
What it is not
Not a heavy hex version of Grade 5. Different head, thread length and rules.
Not interchangeable with A490.
Not replaceable with SAE Grade 8, even though Grade 8 is stronger.
Governing standards: ASTM F3125/F3125M-26; ASTM A563/A563M-26; ASTM F436; RCSC Specification. 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-6707AB · thefastenerapp.com/fastener-guide/technical-reference/astm-f3125-grade-a325 · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
