ASTM A325 Bolts – ISO-Certified Supplier & Global Exporter
ASTM A325 Bolts also called as ASTM A325 Structural Bolts are high-strength, heat treated, 120/105 ksi minimum tensile strength heavy hex fasteners for use in major structural applications. They’re quenched and tempered during manufacture and thus possess the high level of strength required for connections between steel structures, such as in bridges, high-rise buildings, industrial facilities and other important infrastructure. The diameters of these bolts vary from 1/2 to 1-1/2 inches. Currently, two principle types are being manufactured: Type 1 & Type 3. Its tensile strength is between 105 and 120 ksi, depending on size, and that’s one of the reasons that continue to make it a popular choice for structural engineers to specify for AISC-compliant steel construction projects all over the world.
Jade Alloys is an ISO 9001:2015-certified company in Mumbai, India and have been manufacturing and stocking ASTM A325 fasteners for years. A325 Type 1 and 3 bolts come in stock in plain, hot dip galvanized and mechanically galvanized and are accompanied by a Material Test Report (MTR) and EN 10204 3.1/3.2 certificate for each shipment. Our ASTM A325 Heavy Hex Bolts are exported to structural steel contractors, EPC companies and Fabricators in USA, UAE, Saudi Arabia, UK, Germany, Singapore and 50+ countries around the world.
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Nuts Weight Chart
ASTM A325 Bolt Types & Grade Classification
The ASTM A325 specification classifies structural hex bolts by base material and environmental suitability. Understanding the type classification is essential for correct specification on structural steel projects.
| Type | Material | Description & Application |
|---|---|---|
| Type 1 | Medium carbon, carbon boron, or medium carbon alloy steel | Heat-treated (quenched and tempered). Most widely specified for general structural applications — multi-story steel frames, industrial sheds, bridge connections. Can be hot-dip galvanized or mechanically galvanized. |
| Type 2 | Withdrawn | Removed from the ASTM A325 standard in November 1991. Legacy projects specifying Type 2 should contact Jade Alloys for an engineering-equivalent consultation. |
| Type 3 | Weathering steel (atmospheric corrosion-resistant steel) | Heat-treated to the same strength profile as Type 1, with significantly enhanced atmospheric corrosion resistance — similar to Corten/A588 steel. Preferred for exposed outdoor, coastal, marine, and industrial environments. Not recommended for hot-dip galvanizing. |
| Type T (Fully Threaded) | Same as Type 1 or Type 3 base steel | Fully threaded A325. Restricted to a maximum length of 4x the nominal diameter. Used when full clamping thread engagement is required. |
| Type M (Metric) | Same as above | Metric dimensions with the same mechanical properties as imperial versions. Used in metric structural assemblies or international projects. |
Connection Type Codes: SC / N / X
A325 bolts are specified with one of three connection type codes that define installation method and load-transfer mechanism. The bolt itself is identical in all three cases.
| Code | Connection Type | Engineering Requirement |
|---|---|---|
| SC | Slip-Critical Connection | Full pretension required. Bolt clamping force must resist slip under service load. Mandatory for fatigue or reversible-loading connections (bridge girders, moment frames). |
| N | Bearing — Threads in Shear Plane | Snug-tight acceptable for most N-type connections. Threads may be in the shear plane. Used for standard bearing connections in low-fatigue structural steel. |
| X | Bearing — Threads Excluded | Higher shear capacity than N-type. Threads must be positioned outside the shear plane so the unthreaded shank carries shear load. |
ASTM A325 Bolt Specifications & Size Range
| Property | Details |
|---|---|
| Standard | ASTM A325 / ASTM F3125 Grade A325 (current code) |
| Diameter Range (Inch) | 1/2″ to 1-1/2″ (13mm to 38mm) |
| Diameter Range (Metric) | M10 to M110 (Metric A325M) |
| Length Range | 1-1/4″ to 10″ standard; custom lengths to 1500mm available |
| Head Type | Heavy Hex, Hex, Square Head |
| Manufacturing Process | Cold Formed (M2–M24), Hot Forged (M24–M100), CNC Machined (M100+) |
| Thread Types | UNC (standard), UNF, UNEF, Metric Coarse, BSW, BSF, Constant-pitch |
| Finish Options | Plain, Hot-Dip Galvanized (F2329), Mechanically Galvanized (B695 Class 55), Geomet (F1136 Grade 3) |
| Applicable Standards | ASTM, ANSI B18.2.4, ISO, DIN, BS, ASME B18.2.6, JIS, SAE, IFI, EN 14399 |
| Certifications | EN 10204 3.1 MTR, EN 10204 3.2 Third-Party, ISO 9001:2015, PED, NABL |
ASTM A325 vs ASTM F3125 Grade A325 — Key Differences
ASTM A325 was withdrawn in November 2016 and consolidated into the broader ASTM F3125 umbrella standard. For most practical purposes the mechanical requirements are identical. The distinction matters primarily for project specifications, procurement documents, and inspection compliance.
| Factor | ASTM A325 (Withdrawn 2016) | ASTM F3125 Grade A325 (Current) |
|---|---|---|
| Status | Withdrawn — November 2016 | Active — required for new construction per IBC & AISC |
| Min. Tensile (≤1″) | 120 ksi | 120 ksi — identical |
| Min. Tensile (>1″) | 105 ksi | 105 ksi — identical |
| Min. Yield (≤1″) | 92 ksi | 92 ksi — identical |
| Head Marking | A325 | A325 or A325S (TC bolt alternative heads) |
| US Building Code | Legacy specs — many codes still accept | Required for most current US projects (IBC 2018+) |
| Jade Alloys Supply | Yes — legacy A325 stocked | Yes — F3125/A325 stocked |
For projects requiring the current active standard, see our ASTM F3125 Bolts page.
ASTM A325 Bolt Chemical Composition
ASTM A325 Type 1 bolts are manufactured from medium carbon steel, carbon boron steel, alloy steel, or alloy boron steel. Type 3 bolts use weathering steel alloys that form a self-protecting oxide patina on outdoor exposure. Heat analysis values are given below.
Type 1 Chemical Composition (Heat Analysis)
| Element | Carbon Steel | Carbon Boron Steel | Alloy Steel | Alloy Boron Steel |
|---|---|---|---|---|
| Carbon | 0.30 – 0.52% | 0.30 – 0.52% | 0.30 – 0.52% | 0.30 – 0.52% |
| Manganese (min) | 0.60% | 0.60% | 0.60% | 0.60% |
| Phosphorus (max) | 0.04% | 0.04% | 0.04% | 0.04% |
| Sulfur (max) | 0.05% | 0.05% | 0.04% | 0.04% |
| Silicon | 0.13 – 0.32% | 0.08 – 0.32% | 0.13 – 0.37% | 0.13 – 0.37% |
| Boron | — | 0.0005 – 0.003% | — | 0.0005 – 0.003% |
ASTM A325 Bolt Mechanical Properties
| Nominal Diameter | Tensile Strength (min, ksi) | Proof Strength (min, ksi) | Yield Strength (min, ksi) | Elongation (min, %) | Reduction in Area (min, %) |
|---|---|---|---|---|---|
| 1/2″ – 1″ (incl.) | 120 | 85 | 92 | 14% | 35% |
| Over 1″ – 1-1/2″ | 105 | 74 | 81 | 14% | 35% |
Hardness: Bolts up to 1″ diameter — Brinell 253–319 HB (Rockwell C 25–34). Bolts 1-1/8″ to 1-1/2″ — Brinell 223–286 HB (Rockwell C 19–30).
Tensile Load Requirements — Full-Size Bolt Testing
| Bolt Size & Thread Series | Stress Area (in²) | Min. Tensile Load (lbf) | Proof Load — Length Method (lbf) | Proof Load — Yield Method (lbf) |
|---|---|---|---|---|
| 1/2-13 UNC | 0.142 | 17,050 | 12,050 | 13,050 |
| 5/8-11 UNC | 0.226 | 27,100 | 19,200 | 20,800 |
| 3/4-10 UNC | 0.334 | 40,100 | 28,400 | 30,700 |
| 7/8-9 UNC | 0.462 | 55,450 | 39,250 | 42,500 |
| 1-8 UNC | 0.606 | 72,700 | 51,500 | 55,750 |
| 1-1/8-7 UNC | 0.763 | 80,100 | 56,450 | 61,800 |
| 1-1/4-7 UNC | 0.969 | 101,700 | 71,700 | 78,500 |
| 1-3/8-6 UNC | 1.155 | 121,300 | 85,450 | 93,550 |
| 1-1/2-6 UNC | 1.405 | 147,500 | 104,000 | 113,800 |
For full-grade tensile strength comparison across all bolt specifications, see our Bolt Tensile Strength Chart.
ASTM A325 vs A490 vs A193 B7 — Comparative Tensile Strength
Use this table to select the correct bolt grade for your load requirements. ASTM A325 covers standard structural work; A490 is for heavy-load compact connections; A193 B7 is the standard for high-temperature pressure vessel and industrial applications.
| Grade | Material | Size Range | Min. Tensile (ksi) | Min. Yield (ksi) | Galvanizing OK? |
|---|---|---|---|---|---|
| A325 / F3125-A325 | Med. Carbon / Alloy Steel | 1/2″ – 1″ | 120 | 92 | Yes |
| A325 / F3125-A325 | Med. Carbon / Alloy Steel | 1-1/8″ – 1-1/2″ | 105 | 81 | Yes |
| A490 / F3125-A490 | Alloy Steel (Q&T) | 1/2″ – 1-1/2″ | 150 | 130 | No — H2 embrittlement risk |
| A193 B7 | Cr-Mo Alloy Steel | Up to 2-1/2″ | 125 | 105 | Yes |
| A193 B7 | Cr-Mo Alloy Steel | 2-5/8″ – 4″ | 115 | 95 | Yes |
For high-temperature pressure-vessel fastener requirements, see our ASTM A193 B7 Bolts page.
ASTM A325 Heavy Hex Bolt Dimensions Chart
Dimensions per ASME B18.2.6 Heavy Hex Structural Bolt standard. All measurements in inches.
| Bolt Dia. | Body Max | Flats Basic | Flats Max | Flats Min | Corners Max | Corners Min | Head H (Basic) | Head H Max | Thread Length T |
|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 0.515 | 7/8 | 0.875 | 0.850 | 1.010 | 0.969 | 5/16 | 0.323 | 1.00 |
| 5/8 | 0.642 | 1-1/16 | 1.062 | 1.031 | 1.227 | 1.175 | 25/64 | 0.403 | 1.25 |
| 3/4 | 0.768 | 1-1/4 | 1.250 | 1.212 | 1.443 | 1.383 | 15/32 | 0.483 | 1.38 |
| 7/8 | 0.895 | 1-7/16 | 1.438 | 1.394 | 1.660 | 1.589 | 35/64 | 0.563 | 1.50 |
| 1 | 1.022 | 1-5/8 | 1.625 | 1.575 | 1.876 | 1.796 | 39/64 | 0.627 | 1.75 |
| 1-1/8 | 1.149 | 1-13/16 | 1.812 | 1.756 | 2.093 | 2.002 | 11/16 | 0.718 | 2.00 |
| 1-1/4 | 1.277 | 2 | 2.000 | 1.938 | 2.309 | 2.209 | 25/32 | 0.813 | 2.00 |
| 1-3/8 | 1.404 | 2-3/16 | 2.188 | 2.119 | 2.526 | 2.416 | 27/32 | 0.878 | 2.25 |
| 1-1/2 | 1.531 | 2-3/8 | 2.375 | 2.300 | 2.742 | 2.622 | 15/16 | 0.974 | 2.25 |
ASTM A325 Length Tolerance Chart
| Bolt Diameter | Tolerance for Lengths Up to 6″ | Tolerance for Lengths Over 6″ |
|---|---|---|
| 1/2″ | -0.12″ | -0.19″ |
| 5/8″ | -0.12″ | -0.25″ |
| 3/4″ | -0.19″ | -0.25″ |
| 7/8″ | -0.19″ | -0.25″ |
| 1″ | -0.19″ | -0.25″ |
| 1-1/8″ to 1-1/2″ | -0.25″ | -0.25″ |
Use our Bolt Weight Calculator for precise weight estimates by diameter and length.
ASTM A325 Galvanized Bolts Torque Chart
Torque values per AISC Specification Table J3.1. Galvanized + waxed assemblies require approximately 50% of the plain-bolt torque for equivalent clamp force. Always calibrate on a representative sample prior to installation.
| Bolt Size | TPI | Min Tension (lbs) | Max Tension (lbs) | Torque: Galv + Waxed (ft·lbs) | Torque: Plain/Black (ft·lbs) |
|---|---|---|---|---|---|
| 1/2″ | 13 | 12,000 | 14,000 | 50 – 58 | 100 – 117 |
| 5/8″ | 11 | 19,000 | 23,000 | 99 – 120 | 198 – 240 |
| 3/4″ | 10 | 28,000 | 34,000 | 175 – 213 | 350 – 425 |
| 7/8″ | 9 | 39,000 | 47,000 | 284 – 343 | 569 – 685 |
| 1″ | 8 | 51,000 | 61,000 | 425 – 508 | 850 – 1,017 |
| 1-1/8″ | 7 | 64,000 | 77,000 | 600 – 722 | 1,200 – 1,444 |
| 1-1/4″ | 7 | 81,000 | 98,000 | 844 – 1,021 | 1,687 – 2,042 |
| 1-3/8″ | 6 | 97,000 | 117,000 | 1,111 – 1,341 | 2,223 – 2,681 |
| 1-1/2″ | 6 | 118,000 | 143,000 | 1,475 – 1,788 | 2,950 – 3,575 |
ASTM A325 Structural Bolt Coating Options
Coating selection is governed by the ASTM coating standards below. Note that A490 bolts are not approved for hot-dip galvanizing — this is a key supply advantage of A325 for outdoor and coastal structural applications.
| Bolt Grade | F2329 Hot Dip Galvanizing | B695 Mechanical Galv. | F1136 Zinc/Alum. (Geomet) | F2833 Zinc/Alum. |
|---|---|---|---|---|
| A325 Type 1 | Approved | Class 55 | Grade 3 | Grade 1 |
| A325 Type 3 | Not Recommended (affects weathering patina) | Class 55 | Grade 3 | Grade 1 |
| F1852 TC Bolts | N/A | Class 55 | N/A | N/A |
| A490 | Not Approved (H2 embrittlement) | Not Approved | Grade 3 | Grade 1 |
Read more: Galvanized Bolts vs Stainless Steel Bolts comparison guide for corrosive environments.
International Equivalent Grades — ASTM A325 Fasteners
| Standard Body | Equivalent Grade | Standard Name | Notes |
|---|---|---|---|
| ASTM | F3125 Grade A325 | ASTM F3125 | Direct successor — identical mechanical requirements |
| ISO | Grade 8.8S | ISO 4016 / ISO 4014 | Structural metric equivalent — heavy hex variant |
| DIN | DIN 6914 (Grade 8.8) | DIN 6914 | German standard for high-strength structural hex bolts |
| EN (Europe) | EN 14399-4 Grade 8.8 or 10.9 | EN 14399 | European standard for high-strength structural bolt assemblies |
| BS (UK) | BS 4395-1 Grade 8.8 / Grade S | BS 4395-1 | British standard structural bolts — heavy hex format |
| ASME (US) | ASME B18.2.6 | ASME B18.2.6 | Dimensional standard for heavy hex structural bolts |
How to Install ASTM A325 Structural Bolts — AISC Approved Methods
A325 bolts may be installed using three AISC-approved methods per AISC Specification Section J3. All methods begin with bringing the assembly to snug-tight condition — the state achieved by a few impacts of an impact wrench or the full effort of an ironworker using a spud wrench. Always consult the project structural engineer for connection-specific requirements.
Method 1: Turn-of-Nut Method
Bring to snug-tight first, then rotate the nut a specified fraction of a full turn — from 1/3 to 1 full turn depending on bolt length-to-diameter ratio and connection geometry. This is the most common field installation method due to its simplicity and minimal equipment requirements.
Method 2: Calibrated Wrench Method
Use a torque wrench pre-calibrated at the start of each work shift using a Skidmore-Wilhelm bolt tension calibrator. Apply the torque value from the chart above corresponding to the bolt diameter and finish (plain vs. galvanized). Values differ significantly between plain and galvanized+waxed finishes — use the correct column.
Method 3: Direct Tension Indicator (DTI) Method
Install ASTM F959 DTI washers under the bolt head or nut. The DTI protrusions deform plastically under a specific clamp force — when the specified gap closure is achieved, minimum bolt pretension is confirmed visually. Required for slip-critical connections on many bridge and public infrastructure projects.
Compatible Nuts & Washers for ASTM A325 Bolt Assemblies
Selecting the correct mating hardware is mandatory for compliant AISC structural bolt assemblies. Requirements vary by bolt type and finish.
| Hardware | A325 Type 1 (Plain) | A325 Type 1 (Galvanized) | A325 Type 3 (Plain) |
|---|---|---|---|
| Standard Nuts | ASTM A563 Grade C, D, DH, or DH3 | ASTM A563 Grade DH (galv.) | ASTM A563 Grade C3 or DH3 |
| Substitute Nuts | ASTM A194 Grade 2H | ASTM A194 Grade 2H (galv.) | Consult Jade Alloys — Type 3 specific |
| Hardened Washers | ASTM F436 Type 1 | ASTM F436 Type 1 (galv.) | ASTM F436 Type 3 |
| DTI Washers | ASTM F959 Type 325 (optional) | ASTM F959 Type 325 (optional) | ASTM F959 Type 325-3 |
Order compatible nuts: ASTM A563 Nuts | ASTM A194 Grade 2H Nuts — complete bolt assemblies with single-source MTC documentation available on request
ASTM A325 Bolt Testing, Quality Assurance & Certifications
Every batch of ASTM A325 Structural Bolts supplied by Jade Alloys undergoes rigorous quality control per ASTM F3125 and ASTM A325 testing protocols:
- Mechanical Testing: Tensile strength, proof load, yield strength, and elongation — tested full-size per ASTM F606
- Hardness Testing: Rockwell C and Brinell hardness verified at the required ranges per diameter group
- Chemical Analysis: Heat analysis and product analysis for carbon, manganese, phosphorus, sulfur, silicon, and boron
- Dimensional Inspection: Body diameter, head dimensions, thread pitch, and tolerance per ASME B18.2.6
- Head Marking Verification: Manufacturer’s mark and A325 grade marking confirmed per standard requirements
- Lot Traceability: Full heat/lot number documentation enabling cradle-to-project traceability
- Third-Party Inspection: EN 10204 3.2 certification by SGS, Bureau Veritas, Intertek, or TUV on request
Applications of ASTM A325 Bolts by Industry
Structural Steel Construction (Buildings & High-Rise Frames)
ASTM A325 Structural Bolts are the standard fastener for moment connections, beam-column connections, and base plate connections in multi-story steel frames per AISC Specification Section J3. Both SC (slip-critical) and N/X (bearing-type) connections are specified for steel-framed buildings across the USA, EU, and the GCC.
Further reading: Fasteners Used in Steel Structure.
Bridge & Highway Infrastructure
High-strength A325 bolts provide the fatigue resistance required in bridge girder connections, floor beam splices, and cross-frame connections subjected to repeated dynamic loading. Galvanized A325 bolts are the standard choice for exposed bridge connections in coastal and humid environments.
Further reading: Structural Bolts — High Strength Fasteners Guide.
Transmission Towers & Lattice Steel Structures
A325 hex bolts with hot-dip galvanized finish are used in angle-iron lattice tower joints for power transmission, telecommunications, and wind energy structures — where the combination of high preload, fatigue resistance, and galvanic corrosion protection is required over long service lives.
Heavy Industrial & Manufacturing Equipment
Used in machine bed bolting, compressor baseplate connections, gearbox housing connections, and structural steel skid assemblies where high preload and slip-critical clamping is required under dynamic loads. A325 Type 3 is frequently specified in petrochemical processing plants where atmospheric corrosion resistance is critical.
Mining & Oil & Gas Infrastructure
ASTM A325 Type 3 weathering bolts are specified for outdoor structural frames, pipe rack connections, and processing plant structures in corrosive environments — particularly in the Gulf region, North Sea, and tropical Asian markets.
Warehouses, Industrial Sheds & Pre-Engineered Buildings
A325 fasteners are widely used in pre-engineered metal building (PEMB) systems, cold storage structures, and large-span industrial warehouses — a high-growth application segment across India, Southeast Asia, and the Middle East.
See also: ASTM A307 Bolts for lower-strength structural and general-purpose applications.
Packaging, Dispatch & Delivery
| Parameter | Details |
|---|---|
| Standard Packing | Wooden boxes (25 kg per box), corrugated cartons, or steel drums |
| Bulk Packing | 500–1,000 kg wooden crates or pallet-packed for project volumes |
| Documents in Shipment | MTR, Packing List, Commercial Invoice, Weight Certificate, Country of Origin, Bill of Lading |
| Ready Stock Dispatch | 3–5 business days for standard sizes from Mumbai stock |
| Make-to-Order | 2–6 weeks for non-standard sizes, special coatings, or large volumes |
| Export Compliance | ISPM-15 wooden packaging, full export documentation |
| Head Marking | Manufacturer’s mark + A325 grade stamped on each bolt head; heat/lot on packaging |
Estimate bolt weight by diameter and length using our free Bolt Weight Chart.
Why Choose Jade Alloys for ASTM A325 Structural Bolts?
- ISO 9001:2015 Certified: Third-party audited quality management system — ensures consistent product quality on every order.
- Ready Stock — Mumbai: Immediate dispatch on standard sizes. No 6–8 week mill lead times for most requirements.
- Full MTR Documentation: EN 10204 3.1 mill certificates on every shipment. 3.2 (third-party) available for critical projects.
- Export to 50+ Countries: Proven logistics across USA, EU, GCC, SE Asia with full export documentation.
- Both A325 & F3125 Stocked: Legacy A325 and current F3125/A325 — we supply what your project specification requires.
- Technical Team Available: Mon–Sat, 9am–6pm IST for specification queries, equivalence letters, and grade selection.
- Single-Source Assembly: Complete bolt + nut + washer sets with single combined MTC available on request.
Frequently Asked Questions — ASTM A325 Bolts
What is an ASTM A325 bolt?
What is the difference between ASTM A325 Type 1 and Type 3?
What replaced ASTM A325 bolts?
What is the minimum tensile strength of ASTM A325 bolts?
Can ASTM A325 bolts be galvanized?
What is the difference between A325 and A490 bolts?
What nuts and washers should be used with A325 bolts?
Are A325 bolts fully threaded?
What are the three AISC-approved methods for installing A325 structural bolts?
What is the ASTM A325 bolt price in India?
Get a Quote for ASTM A325 Structural Bolts — Same-Day Response
Jade Alloys maintains ready stock of ASTM A325 Heavy Hex Structural Bolts, A325 Type 1, A325 Type 3, A325 Hex Bolts, Stud Bolts, Anchor Bolts, and complete bolt assembly sets in plain, hot-dip galvanized, and mechanically galvanized finishes. All shipments include MTRs and EN 10204 3.1 certification as standard.
Whether you are a structural steel contractor in the USA sourcing F3125 Grade A325 for a bridge project, an EPC company in the UAE procuring A325 Type 3 weathering bolts for a coastal industrial structure, or a fabricator in India needing ex-works priced A325 heavy hex bolts — Jade Alloys delivers the specification, documentation, and supply reliability your project demands.
Phone: +91 9987685906 | Email: sales@jadealloys.com | Contact Jade Alloys
