Weathering Steel Structural Bolts
| Standard | ASTM A588 / ASTM A325 Type 3 · Project specification |
|---|---|
| Material | Weathering Steel |
| Strength Grade | A325 Type 3 / 10.9 |
| Size Range | M12-M36 |
| Surface Treatment | Weathering / Unplated |
01
Product Description
Product Description & Key Specifications
Weathering steel structural bolts are supplied for weathering steel bridges, exposed steel structures and long-life infrastructure where compatible atmospheric corrosion behavior is required without zinc coating. Common references include ASTM A325 Type 3, ASTM A588 project requirements and 10.9 metric project equivalents.
Unlike galvanized structural bolts, weathering steel bolts are normally supplied unplated so that the bolt assembly can develop compatible patina behavior with weathering steel members. Material chemistry, nut grade, washer type and exposure environment should be confirmed because the system depends on compatible corrosion behavior.
These bolts are used with weathering steel heavy hex nuts and ASTM F436 hardened washers where the project requires a complete structural bolting assembly. Procurement should confirm diameter, length, thread length, rotational capacity or assembly testing, lot traceability and coating restrictions.
| Product type | Weathering steel structural bolts |
|---|---|
| Standards | ASTM A588 / ASTM A325 Type 3 / project specification |
| Material | Weathering steel |
| Strength grade | A325 Type 3 / 10.9 project equivalent |
| Size range | M12-M36 |
| Common models | M16 x 50, M20 x 70, M22 x 80, M24 x 90, M30 x 120 |
| Thread type | Heavy structural bolt thread length by standard or drawing |
| Surface finish | Weathering / Unplated |
| Documentation | MTC, CoC, lot traceability and dimensional report on request |
Dimensions & SpecificationsASME B18.2.6 Heavy Hex Bolts
Technical Drawing
Dimensional Table
| Parameter | 1 | 1/2 | 1-1/8 | 1-1/4 | 1-3/8 | 1-1/2 | 3/4 | 5/8 | 7/8 |
|---|---|---|---|---|---|---|---|---|---|
| P | 8 | 13 | 7 | 7 | 6 | 6 | 10 | 11 | 9 |
| ds/max | 1.022 | 0.515 | 1.149 | 1.277 | 1.404 | 1.531 | 0.768 | 0.642 | 0.895 |
| ds/min | 0.976 | 0.482 | 1.098 | 1.223 | 1.345 | 1.47 | 0.729 | 0.605 | 0.852 |
| k/max | 0.627 | 0.323 | 0.718 | 0.813 | 0.878 | 0.974 | 0.483 | 0.403 | 0.563 |
| k/min | 0.591 | 0.302 | 0.658 | 0.749 | 0.81 | 0.902 | 0.455 | 0.378 | 0.531 |
| s/max | 1.625 | 0.875 | 1.812 | 2 | 2.188 | 2.375 | 1.25 | 1.062 | 1.438 |
| s/min | 1.575 | 0.85 | 1.756 | 1.938 | 2.119 | 2.3 | 1.212 | 1.031 | 1.394 |
| r/max | 0.093 | 0.031 | 0.093 | 0.093 | 0.093 | 0.093 | 0.062 | 0.062 | 0.062 |
| r/min | 0.062 | 0.009 | 0.062 | 0.062 | 0.062 | 0.062 | 0.021 | 0.021 | 0.031 |
02
Selection
Selection Advantages by Application
Weathering Steel Bridges
A325 Type 3 weathering bolts are used in bridge girders, splice plates and exposed steelwork where unplated weathering behavior is required. Common RFQs include M20 x 70, M22 x 80 and M24 x 90.
Bridge fastenersExposed Infrastructure
Weathering steel bolts support outdoor pedestrian bridges, railings, towers and infrastructure frames where compatible patina appearance and long-life exposure are specified.
Infrastructure fastenersRailway & Transit Structures
Weathering structural bolting can be specified for selected exposed rail infrastructure steelwork. Confirm whether the project requires A325 Type 3, metric 10.9 equivalent or local approval documents.
Railway infrastructure fasteners03
Assembly
Recommended Matching Products
04
Manufacturing
Manufacturing & Quality Control
Manufacturing CapabilityQuality Control
Hot forging and thread rolling for structural bolt geometryWeathering steel chemistry and heat number verification
Unplated finish control for weathering steel compatibilityThread gauge, head marking and dimensional inspection
Assembly preparation with compatible nuts and washersLot traceability and material certificate review
Project-based structural bolt productionTensile, hardness, wedge tensile or rotational capacity testing arranged when specified
Crate or assembly packaging by lotMTC, CoC and inspection report prepared on request
05
FAQ
Common Questions Before RFQ
Why are weathering steel bolts supplied unplated?
Weathering steel assemblies are often supplied unplated so the bolt, nut and connected weathering steel can develop compatible patina behavior. Zinc coating may be prohibited by the project specification.
What nuts should be used with A325 Type 3 bolts?
Weathering steel heavy hex nuts such as ASTM A563 Grade C3 or DH3 are commonly specified. The final nut grade should follow the structural bolting specification.
What sizes are commonly requested?
Common RFQ models include M16 x 50, M20 x 70, M22 x 80, M24 x 90 and M30 x 120. Final length and thread length should follow the connection drawing.
Are these bolts the same as Corten bolts?
Corten is often used informally for weathering steel, but procurement should specify the actual standard and material chemistry, such as ASTM A325 Type 3 or project-approved weathering steel.
Can bolt-nut-washer assemblies be supplied?
Yes. Weathering structural bolts can be supplied with compatible heavy hex nuts and hardened washers when the project specification is confirmed.
Need weathering steel structural bolts for bridges?
Send your standard, diameter, length, connection drawing, nut/washer requirement, testing scope and lot traceability needs. Our team can quote weathering steel structural bolt assemblies for exposed infrastructure.
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