Technically reviewed by Vincent, Founder at HEXVARO
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Quick answer
Quick answer: A325/A490 companion hardware
Under ASTM F3125, ASTM A563, ASTM F436 and the RCSC 2020 specification, plain F3125 Grade A325 Type 1 permits A563 C, C3, D, DH or DH3 nuts with an F436 Type 1 washer. Plain A490 Type 1 uses DH or DH3 with F436 Type 1; coated assemblies are more restrictive and must follow the governing structural-joint specification.
| Bolt | Finish / type | Permitted A563 nut grades | Washer | Inquiry |
|---|---|---|---|---|
| F3125 A325 or F1852 | Type 1, plain | C, C3, D, DH or DH3 | F436 Type 1 | Quote this size |
| F3125 A325 or F1852 | Type 1, galvanized or coated | DH | F436 Type 1 | Quote this size |
| F3125 A490 or F2280 | Type 1, plain | DH or DH3 | F436 Type 1 | Quote this size |
| F3125 A490 or F2280 | Type 1, approved coating | DH | F436 Type 1 | Quote this size |
Sourcing these sizes? ASTM A563 heavy hex nuts ASTM F436 hardened washers
A325 and A490 companion hardware
Reference basis: ASTM F3125/F3125M-26 bolt groups, ASTM A563/A563M-24 nuts, ASTM F436/F436M-24 washers and the RCSC Specification for Structural Joints Using High-Strength Bolts (2020). The table is a procurement cross-reference; the project specification controls.
| Bolt group | Finish / type | Permitted A563 nut grades | F436 washer | Inquiry |
|---|---|---|---|---|
| F3125 A325 or F1852 | Type 1, plain | C, C3, D, DH or DH3 | F436 Type 1 | Quote this size |
| F3125 A325 or F1852 | Type 1, galvanized or coated | DH | F436 Type 1 | Quote this size |
| F3125 A325 or F1852 | Type 3, plain | C3 or DH3 | F436 Type 3 | Quote this size |
| F3125 A490 or F2280 | Type 1, plain | DH or DH3 | F436 Type 1 | Quote this size |
| F3125 A490 or F2280 | Type 1, approved coating | DH | F436 Type 1 | Quote this size |
| F3125 A490 or F2280 | Type 3, plain | DH3 | F436 Type 3 | Quote this size |
Need these ASTM F3125/F3125M-26 / A563/A563M-24 / F436/F436M-24 / RCSC 2020 sizes? Request a quote
What the A563 and F436 callouts mean
Under ASTM A563/A563M-24 and ASTM F436/F436M-24, A563 identifies the carbon- or alloy-steel nut grade and form; DH is the common heavy-hex high-strength nut family used with structural bolts. F436 identifies the hardened washer family. The 3 suffix follows Type 3 weathering-steel bolt assemblies, so do not mix Type 1 and Type 3 hardware casually.
| Callout | Meaning for purchasing | Inquiry |
|---|---|---|
| A563 DH | Heavy-hex structural nut grade | Quote this size |
| A563 DH3 | Weathering-steel heavy-hex nut grade | Quote this size |
| F436 Type 1 | Hardened washer for Type 1 assemblies | Quote this size |
| F436 Type 3 | Hardened washer for Type 3 assemblies | Quote this size |
Need these ASTM F3125/F3125M-26 / A563/A563M-24 / F436/F436M-24 / RCSC 2020 sizes? Request a quote
Finish and overtapping checks
- Match the nut coating process to the galvanized or coated bolt assembly and confirm overtapping where required.
- Do not use a plain nut on a galvanized structural bolt merely because the thread appears to fit.
- Request bolt, nut and washer markings, certificates and the applicable RCSC or project specification in the quotation package.
Order these sizes from HEXVARO
Send your size list with grade, finish and quantity — we reply within 2 working hours with price, lead time and shipping terms.
- Reply: within 2 working hours
- MOQ: 500 pcs per specification
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- Experience: Founder with 10+ years in the fastener industry
Frequently asked questions
What nut goes with an A325 bolt?
For a plain Type 1 A325 assembly, the table permits A563 C, C3, D, DH or DH3 nuts with an F436 Type 1 washer. For galvanized or coated Type 1, the table lists A563 DH.
What nut goes with an A490 bolt?
For a plain Type 1 A490 assembly, the table lists A563 DH or DH3 with an F436 Type 1 washer. An approved coated Type 1 assembly lists A563 DH; confirm the project specification.
What is the difference between A563 DH and DH3?
DH is the heavy-hex structural nut grade for Type 1 assemblies; DH3 is the weathering-steel counterpart used with Type 3 structural bolts.
Can I use a standard washer with an A325 or A490 bolt?
The matching table calls for an ASTM F436 hardened washer: Type 1 for Type 1 assemblies and Type 3 for Type 3 assemblies. Do not substitute a general-purpose washer without approval.
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