ASTM A325 Structural Bolts are high-strength Heavy Hex structural bolts historically specified under ASTM A325 and currently covered by ASTM F3125/F3125M Grade A325. Grade A325 bolts have a minimum tensile strength of 120 ksi (830 MPa) and are available as Type 1 or Type 3 structural bolts.
ASTM A325 Structural Bolts are high-strength structural fasteners used for joining steel members in load-bearing structural connections. They feature a heavy hex head and are manufactured from quenched and tempered steel or alloy-steel grades according to the applicable requirements.
The original ASTM A325 specification has been consolidated into ASTM F3125/F3125M, so new technical specifications generally identify these fasteners as ASTM F3125 Grade A325 Bolts. ASTM F3125 identifies Grade A325 as a 120 ksi minimum tensile-strength grade and provides Type 1 and Type 3 classifications for Heavy Hex structural bolts.
We manufacture and supply ASTM A325 Heavy Hex Bolts for structural steel fabrication, bridges, towers, industrial buildings, infrastructure and other applications where high-strength bolted connections are required.
What Are ASTM A325 Structural Bolts?
ASTM A325 Structural Bolts are high-strength structural bolts originally manufactured to ASTM A325 requirements and now covered under ASTM F3125/F3125M Grade A325.
They are different from ordinary hex bolts because structural bolts are designed specifically for engineered structural connections. Their heavy hex heads provide a larger bearing surface and facilitate installation using structural bolting tools.
The current ASTM F3125 specification classifies structural bolts according to grade, type and style. Grade indicates the strength level, Type identifies the raw-material chemical composition and Style identifies the Heavy Hex or Twist-Off configuration.
Table of Contents
- ➤ What Are ASTM A325 Structural Bolts?
- ➤ Types of ASTM A325 Structural Bolts
- ➤ ASTM A325 Chemical Composition
- ➤ ASTM A325 Mechanical Properties
- ➤ ASTM A325 Heavy Hex Bolts Specifications
- ➤ ASTM A325 Heavy Hex Bolt Dimensions
- ➤ ASTM A325 Heavy Hex Bolts Weight Chart
- ➤ ASTM A325 Equivalent Grades Chart
- ➤ ASTM A325 vs ASTM F3125 Grade A325
- ➤ Plain Finish ASTM A325 Heavy Hex Bolts
- ➤ ASTM A325 Structural Bolts Manufacturing Process
- ➤ Applications of ASTM A325 Structural Bolts
- ➤ ASTM A325 Structural Fasteners Exporter and Supplier
- ➤ Why Choose Us as an ASTM A325 Structural Fasteners Exporter?
Types of ASTM A325 Structural Bolts
ASTM A325 bolts are primarily divided into Type 1 and Type 3 based on their material chemistry.
| Type | Description | Strength | Typical Application |
|---|---|---|---|
| Type 1 | Carbon, carbon-boron or alloy steel | 120 ksi min. | General structural connections |
| Type 3 | Weathering steel | 120 ksi min. | Atmospheric/weather-exposed structures |
| A325M Type 1 | Metric structural version | 830 MPa min. | Metric structural connections |
| A325M Type 3 | Metric weathering-steel version | 830 MPa min. | Exposed metric structural connections |
ASTM identifies Type 1 Grade A325 material as carbon steel, carbon-boron steel, alloy steel or alloy steel with boron addition, while Type 3 is based on weathering-steel chemistry.
ASTM A325 Type 1 Heavy Hex Bolts
ASTM A325 Type 1 Heavy Hex Bolts are the standard choice for many conventional structural steel connections. They are heat treated to achieve the required high-strength properties and can be manufactured from qualifying carbon or alloy-steel compositions.
ASTM A325 Type 3 Weathering Steel Bolts
ASTM A325 Type 3 Weathering Steel Bolts are manufactured from weathering-steel compositions designed for improved atmospheric corrosion resistance. They are useful in exposed steel structures where compatibility with weathering-steel construction is required.
ASTM A325 Chemical Composition
Type 1 – Chemical Composition
| Element | Requirement, % |
|---|---|
| Carbon | 0.30–0.52 |
| Manganese | 0.60 min. |
| Phosphorus | 0.035 max. |
| Sulfur | 0.040 max. |
| Silicon | 0.15–0.30 |
| Boron | 0.003 max. |
| Copper | As specified by qualifying composition |
| Nickel | As specified by qualifying composition |
| Chromium | As specified by qualifying composition |
| Molybdenum | As specified by qualifying composition |
| Vanadium | Not specified |
| Titanium | Not specified |
Type 3 – Chemical Composition
| Element | Type 3 Composition / Requirement |
|---|---|
| Carbon | 0.33–0.40% or 0.38–0.48% depending on composition route |
| Manganese | 0.90–1.20% or 0.70–0.90% |
| Phosphorus | 0.035% max. |
| Sulfur | 0.040% max. |
| Silicon | 0.15–0.30% or 0.30–0.50% |
| Copper | 0.20–0.40% or 0.20–0.60% |
| Nickel | 0.25–0.45% or 0.50–0.80% |
| Chromium | 0.45–0.65% or 0.50–0.75% |
| Other Alloying Elements | According to applicable Type 3 composition/corrosion-index requirements |
ASTM A325 Mechanical Properties
A325 High Strength Bolts are heat treated to provide high tensile and yield strength suitable for structural connections.
| Mechanical Property | Grade A325 Requirement |
|---|---|
| Minimum Tensile Strength | 120 ksi / 830 MPa |
| Minimum Yield Strength | 92 ksi / 660 MPa |
| Minimum Elongation | 14% |
| Minimum Reduction of Area | 35% |
| Hardness | 253–319 HB |
| Heat Treatment | Quenched and tempered |
| Strength Grade | 120 ksi |
ASTM A325 Heavy Hex Bolts Specifications
| Specification | Details |
|---|---|
| Current Standard | ASTM F3125/F3125M |
| Legacy Standard | ASTM A325 |
| Grade | F3125 Grade A325 |
| Types | Type 1, Type 3 |
| Style | Heavy Hex |
| Material | Carbon / Alloy Steel, Heat Treated |
| Tensile Strength | 120 ksi min. |
| Yield Strength | 92 ksi min. |
| Inch Sizes | ½–1½ in. |
| Metric Grade | A325M |
| Metric Sizes | M12–M36 |
| Thread | UNC / applicable structural thread requirements |
| Finish | Plain or specified coating/finish |
| Application | Structural steel connections |
ASTM A325 Heavy Hex Bolt Dimensions
| Nominal Diameter | Across Flats | Head Height | Basic Thread Length |
|---|---|---|---|
| ½" | 7/8" | 5/16" | 1.00" |
| 5/8" | 1-1/16" | 25/64" | 1.25" |
| ¾" | 1-1/4" | 15/32" | 1.38" |
| 7/8" | 1-7/16" | 35/64" | 1.50" |
| 1" | 1-5/8" | 39/64" | 1.75" |
| 1-1/8" | 1-13/16" | 11/16" | 2.00" |
| 1-1/4" | 2" | 25/32" | 2.00" |
| 1-3/8" | 2-3/16" | 27/32" | 2.25" |
| 1-1/2" | 2-3/8" | 15/16" | 2.25" |
ASTM A325 Heavy Hex Bolts Weight Chart
Bolt weight varies with diameter and length. The following chart gives representative weights for 100 ASTM F3125 Grade A325/A490 Heavy Hex structural bolt-and-nut sets, based on published structural-bolt weight data.
| Length | ½" | 5/8" | ¾" | 7/8" | 1" | 1-1/8" | 1-1/4" | 1-3/8" | 1-1/2" |
|---|---|---|---|---|---|---|---|---|---|
| 1" | 16.5 | 29.4 | 47.0 | — | — | — | — | — | — |
| 1¼" | 17.8 | 31.3 | 49.6 | 74.4 | 104 | — | — | — | — |
| 1½" | 19.2 | 33.1 | 52.2 | 78.0 | 109 | 148 | 197 | — | — |
| 1¾" | 20.5 | 35.3 | 55.3 | 81.9 | 114 | 154 | 205 | 261 | 333 |
| 2" | 21.9 | 37.4 | 58.4 | 86.1 | 119 | 160 | 212 | 270 | 344 |
| 2¼" | 23.3 | 39.8 | 61.6 | 90.3 | 124 | 167 | 220 | 279 | 355 |
| 2½" | 24.7 | 41.7 | 64.7 | 94.6 | 130 | 174 | 229 | 290 | 366 |
| 2¾" | 26.1 | 43.9 | 67.8 | 98.8 | 135 | 181 | 237 | 300 | 379 |
| 3" | 27.4 | 46.1 | 70.9 | 103 | 141 | 188 | 246 | 310 | 391 |
ASTM A325 Equivalent Grades Chart
Because ASTM A325 has been incorporated into ASTM F3125, the most important "equivalent" is the current F3125 Grade A325 designation. Other standards should not automatically be treated as direct equivalents because their chemistry, dimensions, testing and structural-joint requirements can differ.
| ASTM A325 Reference | Current / Comparable Designation | Remarks |
|---|---|---|
| ASTM A325 Type 1 | ASTM F3125 Grade A325 Type 1 | Current specification designation |
| ASTM A325 Type 3 | ASTM F3125 Grade A325 Type 3 | Current weathering-steel designation |
| ASTM A325M Type 1 | ASTM F3125 Grade A325M Type 1 | Metric version |
| ASTM A325M Type 3 | ASTM F3125 Grade A325M Type 3 | Metric weathering-steel version |
| ASTM A325 Heavy Hex | F3125 Grade A325 Heavy Hex | Current Heavy Hex designation |
| ASTM A325 | ASTM F3125/F3125M | A325 was consolidated into F3125 |
| EN structural bolting | EN 14399 series | Comparable structural system; not automatically equivalent |
| ISO/other high-strength bolt grades | Depends on grade | Must be technically verified before substitution |
ASTM confirms that F3125/F3125M consolidated and replaced A325, A325M and other structural bolting specifications.
ASTM A325 vs ASTM F3125 Grade A325
| Feature | ASTM A325 | ASTM F3125 Grade A325 |
|---|---|---|
| Status | Legacy/withdrawn designation | Current specification |
| Strength | A325 requirements | 120 ksi minimum |
| Type | Type 1 & Type 3 | Type 1 & Type 3 |
| Style | Heavy Hex | Heavy Hex |
| Inch Size | ½–1½" | ½–1½" |
| Metric Version | A325M | A325M under F3125 |
| Current Use | Common search/drawing term | Current technical designation |
Plain Finish ASTM A325 Heavy Hex Bolts
Plain Finish ASTM A325 Heavy Hex Bolts are supplied without an additional protective metallic coating. The plain surface is often selected for indoor structural applications or where the engineering specification does not require a corrosion-resistant coating.
For outdoor, marine, industrial or corrosive environments, the appropriate coating or Type 3 weathering-steel solution should be selected based on the project requirements.
When coated bolts are specified, compatibility between the bolt, nut, washer, coating and lubrication requirements should be verified before installation.
ASTM A325 Structural Bolts Manufacturing Process
Applications of ASTM A325 Structural Bolts
ASTM A325 Structural Bolts are commonly used in applications requiring high-strength structural connections, including:
- Structural steel buildings
- Bridges and highway structures
- Steel towers
- Industrial plants
- Power and energy projects
- Heavy equipment structures
- Commercial buildings
- Warehouses and fabrication structures
- Steel columns and beams
- Structural frames and connections
- Outdoor steel structures
- Weathering steel construction
Their heavy hex head provides a larger bearing surface than standard hex bolts, making them suitable for structural steel connection assemblies.
ASTM A325 Structural Fasteners Exporter and Supplier
As an ASTM A325 Structural Fasteners Exporter, we supply high-strength structural bolting solutions for domestic and international projects. We understand that structural fasteners require more than simply matching a grade designation. Bolt type, size, finish, heat treatment, thread configuration, nut compatibility, washer requirements and inspection documentation must all match the project specification.
We offer ASTM A325 Heavy Hex Bolts Supplier in India solutions for customers requiring consistent dimensions, material traceability and project-specific documentation.
For customers searching for an ASTM A325 Structural Bolts Manufacturer in Mumbai, we can provide structural bolt requirements based on size, quantity, type, finish and applicable standard.
Why Choose Us as an ASTM A325 Structural Fasteners Exporter?
We supply ASTM A325 Structural Bolts for domestic and international structural projects with attention to material grade, dimensions, finish, quantity and documentation.
Our supply capability includes:
- ASTM F3125 Grade A325 Bolts
- ASTM A325 Type 1 Heavy Hex Bolts
- ASTM A325 Type 3 Weathering Steel Bolts
- Plain Finish ASTM A325 Heavy Hex Bolts
- Custom bolt lengths
- Bulk structural fastener orders
- Inspection and testing documentation
- Export-quality packaging
- Project-specific requirements
If you are looking for an ASTM A325 Structural Bolts Manufacturer in Mumbai or an ASTM A325 Heavy Hex Bolts Supplier in India, share your required diameter, length, Type, finish and quantity with us. We can review the requirement and offer the appropriate current ASTM F3125 Grade A325 specification.
Request a Quote for ASTM A325 Structural Bolts
For pricing and technical assistance, provide the bolt diameter, length, Type 1 or Type 3 requirement, finish, quantity and applicable standard.
We can supply high-strength ASTM A325 Heavy Hex Bolts with the required inspection and documentation for structural applications.
Contact us today for ASTM F3125 Grade A325 Structural Bolts and Heavy Hex Structural Fasteners.
Frequently Asked Questions
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