Structural Bolts

Holding the world together with high quality A325/A490 bolts

ASTM A325 (F3125) Structural Nuts And Bolts

The ASTM A325 specification applies to high-strength heavy hex structural bolts with diameters ranging from 1/2” to 1-1/2”. These bolts are specifically designed for structural connections and feature shorter thread lengths compared to standard hex bolts.

Engineered to be tightened to near their proof strength, these bolts are intended to achieve significant bolt tension. The standard requires that they be tightened to at least 70% of their tensile strength. Manufactured from the same material as standard bolts (ASTM F568M for metric equivalents), these bolts feature a thicker and wider heavy hex head, which enhances load distribution in structural applications.

In 2016, ASTM replaced the A325 specification with ASTM F3125. However, to prevent confusion, the bolt head markings remain unchanged, and "A325" is retained as a grade designation within the new standard.

Import

LBs70

Keg Weight

FEATURES

Meet ASTM Certifications

Rocap Test Available on Demand

Universal Skids

Keg Material (Plastic)

Easily Resealable

Heavy Duty Handle On Keg

English Milltest

Automated Milltest Sending

North American (Domestic)

LBs200

Keg Weight

FEATURES

Meet ASTM Certifications

Rocap Test Pass

Universal Skids

Keg Material (Steel)

Easily Resealable

English Milltest

Free Taxes Canada/USA

Automated Milltest Sending

Technical Specifications

TYPES OF F3125 GRADE A325 BOLTS
TYPE 1 Medium carbon, carbon boron, or medium carbon alloy steel. (STANDARD)
TYPE 2 Withdrawn November 1991.
TYPE 3 Weathering steel.
T Fully threaded A325. (Restricted to 4 times the diameter in length).
M Metric A325.
Bolt Diam. E F G H T
Body Diam. With Across Flat With Across Corners Head Height Thread Length
Max Basic Max Min Max Min Basic Max Min Basic
1/2-13 0.515 7/8 0.875 0.850 1.010 0.969 5/16 0.323 0.302 1.00
5/8-11 0.642 1 1/16 1.062 1.031 1.227 1.175 25/64 0.403 0.378 1.25
3/4-10 0.768 1 1/4 1.250 1.212 1.443 1.383 15/32 0.483 0.455 1.38
7/8-9 0.895 1 7/16 1.438 1.394 1.660 1.589 35/64 0.563 0.531 1.50
1-8 1.022 1 5/8 1.625 1.575 1.876 1.796 39/64 0.627 0.591 1.75
1 1/8-7 1.149 1 13/16 1.812 1.756 2.093 2.002 11/16 0.718 0.658 2.00
1 1/4-7 1.277 2 2.00 1.938 2.309 2.209 25/32 0.813 0.749 2.00
1 3/8-6 1.404 2 3/16 2.188 2.119 2.526 2.416 27/32 0.878 0.810 2.25
1 1/2-6 1.531 2 3/8 2.375 2.300 2.742 2.622 15/16 0.974 0.902 2.25
F3125 Grade A325 Dimensions, Threads & Grade Marking
Type 1 Type 3
Style – Heavy Hex Bolts
Dimensions, ASMEB B18,2,6 B18,2,6
Thread Fit, ASMEB B1.1 UNC 2A B1.1 UNC 2A
Grade MarkingA, C A325 A325

A A325 and A325M bolts lengths up to 4D which are fully threaded but which are not required to be fully threaded by the relevant ASME standard shall be marked with a “T”, see Supplementary Requirement S1. Bolts with any other non-standard dimensions, including thread length, shall be marked with an “S”, see Supplementary Requirement S2.
B Manufactured to the latest revision at the time of manufacture, UNC for inch series and Metric Coarse (MC) for Metric Series.
C Previously used markings may be sold and used indefinitely, bolts must be manufactured to current marking requirements upon initial publication of this standard.

Source: The table above is inspired by Table 1 from the ASTM F3125 Standard that you can purchase on the ASTM Website

Bolt Diameter(inch) Length to add (inch)
No Washer / One Nut One Washer / One Nut Two Washers / One Nut
1/2 11/16 55/64 1 1/64
5/8 7/8 1 1/32 1 3/16
3/4 1 1 5/32 1 5/16
7/8 1 1/8 1 9/32 1 7/16
1 1 1/4 1 13/32 1 9/16
1 1/8 1 1/2 1 21/32 1 13/16
1 1/4 1 5/8 1 25/32 1 15/16
1 3/8 1 3/4 1 29/32 2 1/16
1 1/2 1 7/8 2 1/32 2 3/16

 

** In the case of a Beveled Washer being used, add 5/16″ to the ‘No Washer’ corresponding column.

E.G : If you are looking to clamp 2 Metal Frames of 3/8″ thick each , using 3/4″ diameter bolt assembled structural bolts with one washer. The length of the bolt would need to be (3/8″ X 2) + 1 5/32″ = 1.90625″ rounding up on the size (increment by 1/4″ inch) would give us 3/4″ X 2″ A325 Structural Bolts.

Have any question ? Our professional team will gladly help you, you may send any inquiry at  Boulonseclair@boulonseclair.com .

Chemical RequirementsC For ASTM F3125 Grade A325-1 & F1852-1 Bolts
Element Carbon or AlloyD with or Without Boron
Carbon 0.30 – 0.52
Manganese, min 0.60 min
Phosphorus Max 0.035
Sulfur Max 0.040
Silicon 0.15 – 0.30
Boron 0.003 max
Copper B
Nickel B
Chromium B
Vanadium B
Molybdenum B
Titanium B

B Not Specified.
C Product analysis that is outside the specified range is permitted provided it is within 10% of the value required of the heat analysis. For example Heat analysis C 0.30-0.52 = Product analysis C 0.27-0.57 or Phosphorus max Heat analysis 0.040 = Product analysis 0.044.
D Steel, as defined by the American Iron and Steel Institute, shall be considered to be alloy when the maximum of the range given for the content of alloying elements exceeds one or more of the following limits: Manganese, 1.65 %; silicon, 0.60 %; copper, 0.60 % or in which a definite range or a definite minimum quantity of any of the following elements is specified or required within the limits of the recognized field of constructional alloy steels: aluminum, chromium up to 3.99 %, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, zirconium, or any other alloying elements added to obtain a desired alloying effect.

Source: The table above is inspired by Table 2 from the ASTM F3125 Standard that you can purchase on the ASTM Website

Chemical RequirementsC For ASTM F3125 Grade A325-3

Element Composition A Composition B Based on Corrosion IndexE
Carbon 0.33 – 0.40 0.38 – 0.48 0.30 – 0.52 max
Manganese 0.90 – 1.20 0.70 – 0.90 0.60 min
Phosphorus Max 0.035 0.035 0.035
Sulfur Max 0.040 0.040 0.040
Silicon 0.15 – 0.30 0.30 – 0.50 B
Boron B B B
Copper 0.25 – 0.45 0.20 – 0.40 0.20 – 0.60B
Nickel 0.25 – 0.45 0.50 – 0.80 0.20B, C min
Chromium 0.45 – 0.65 0.50 – 0.75 0.45B min
Vanadium B B B
Molybdenum B 0.06 max 0.10B, C min
Titanium B B B

B Not Specified.
C Product analysis that is outside the specified range is permitted provided it is within 10% of the value required of the heat analysis. For example Heat analysis C 0.30-0.52 = Product analysis C 0.27-0.57 or Phosphorus max Heat analysis 0.040 = Product analysis 0.044.
E Type 3 bolts conforming to Table 2, or Type 3 bolts which have a copper minimum Heat Analysis of 0.20% and a Corrosion Index of 6 or higher as calculated from the Heat Analysis as described in Guide G101 Predictive method based on the data of Larabee and and Coburn shall be accepted: I = 26.01 (% Cu) + 3.88 (% Ni) + 1.20 (% Cr) + 1.49 (% Si) + 17.28 (% P) – 7.29 (% Cu) (% Ni) – 9.10 (%Ni) (% P) – 33.39 (% Cu)2

Source: The table above is inspired by Table 2 from the ASTM F3125 Standard that you can purchase on the ASTM Website

F3125 Grade A325 & F1852 TENSILE STRENGHT REQUIREMENTS FOR BOLTS TESTED FULL SIZE

Stress AreaA Tensile Min. Proof LoadC Min. Proof LoadD Min.
in. in2. ft-lb ft-lb ft-lb
1/2-13 0.142 in2. 17 050 ft-lb 12 050 ft-lb 13 050 ft-lb
5/8-11 0.226 in2. 27 100 ft-lb 19 200 ft-lb 20 800 ft-lb
3/4-10 0.334 in2. 40 100 ft-lb 28 400 ft-lb 30 700 ft-lb
7/8-9 0.462 in2. 55 450 ft-lb 39 250 ft-lb 42 500 ft-lb
1-8 0.606 in2. 72 700 ft-lb 51 500 ft-lb 55 750 ft-lb
1 1/8-7 0.763 in2. 91 600 ft-lbB 64 900 ft-lbB 70 250 ft-lbB
1 1/4-7 0.969 in2. 116 300 ft-lbB 82 400 ft-lbB 89 200 ft-lbB
1 3/8-6 1.155 in2. 138 600 ft-lbB 98 200 ft-lbB 106 300 ft-lbB
1 1/2-6 1.405 in2. 168 600 ft-lbB 119 500 ft-lbB 129 300 ft-lbB
Above Values Based On * 120 000 psi 85 000 psi 92 000 psi

A The stress area is calculated as follows for inch: AS = 0.7854 [D – (0.9743/P)]2; for Metric: AS = 0.7854 (D – 0.9382P)2; where AS = Stress Area, D = Nominal Bolt Size, and P = thread pitch.
B Previous versions of A325 and F1852 required tensile testing based on 105 ksi min. tensile strength for larger diameters, and proof load testing of 74 ksi (length measurement method) and 81 ksi (yield strength method). This specification was changed to align with AISC/RCSC design and installation values and metric equivalent strength levels.
C Proof load length measurement.
D Alternative Proof load Yield Strength Method.

Source: The table above is inspired by Table 4 from the ASTM F3125 Standard that you can purchase on the ASTM Website

A490 Mechanical Properties

 

Size Tensile, ksi Yield, ksi Elong. %, min RA %, min
1/2 – 1-1/2 150-173 130 14 40

A490 Chemical Properties

 

Type 1 Bolts
Element Sizes 1/2 to 1-3/8 Size 1-1/2
Carbon, max 0.30 – 0.48% 0.35 – 0.53%
Phosphorus, max 0.040% 0.040%
Sulfur, max 0.040% 0.040%
Alloying Elements * *
* Steel, as defined by the American Iron and Steel Institute, shall be considered to be alloy when the maximum range given for the content of alloying elements exceeds one of more of the following limits: Manganese, 1.65%, silicon, 0.60%, copper, 0.60%, or in which a definite range or a minimum quantity of any of the following elements is specified or required within the limits of the recognized field of constructional alloy steels: aluminum, chromium up to 3.99%, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, zirconium or any other alloying elements added to obtain a desired alloying effect.
Type 3 Bolts
Element Sizes 1/2 to 3/4 Size above 3/4
Carbon 0.20 – 0.53% 0.30 – 0.53%
Manganese, min 0.40% 0.40%
Phosphorus, max 0.035% 0.035%
Sulfur, max 0.040% 0.040%
Copper 0.20 – 0.60% 0.20 – 0.60%
Chromium, min 0.45% 0.45%
Nickel, min 0.20% 0.20%
or
Molybdenum, min 0.15% 0.15%
PERMITTED COATINGH
F2329A B695A F1136E,G F2833F,G
Bolt Hot-Dip Galvanized Mechanically Deposited Zinc Zinc/Aluminum Zinc/Aluminum
A325 50 μm Class 55 Grade 3 Grade 1
DIMENSIONAL LIMITS BOLT PITCH DIAM. BOLT PITCH DIAM. BOLT PITCH DIAM. BOLT PITCH DIAM.
OS AFTER COATINGC,D OS AFTER COATINGC OS AFTER COATINGC OS AFTER COATINGC
IN. IN. IN. IN.
1/2-13 UNC 0.018 0.012 0.006 0.006
5/8-11 UNC 0.020 0.013 0.007 0.007
3/4-10 UNC 0.020 0.013 0.007 0.007
7/8-9 UNC 0.022 0.015 0.008 0.008
1-8 UNC 0.024 0.016 0.008 0.008
1 1/8-7 UNC 0.024 0.016 0.008 0.008
1 1/4-7 UNC 0.024 0.016 0.008 0.008
1 3/8-6 UNC 0.027 0.018 0.010 0.010
1 1/2-6 UNC 0.027 0.018 0.0.10 0.010

A Supplementary nut lubrication to A563 S1 is required for hot dip and mechanically deposited zinc coatings.
C Bolt pitch oversize limit in case of dispute. Material within the plain gauge limits which meets the coating thickness requirements and assembles freely need not be
measured to this tolerance.
D Hot-Dip galvanized is typically tapped after coating. Others coatings are typically applied after nut tapping.
E Grade 5 of this coating meets the supplementary lubrication requirements of A563 S1.
F Grade 1 of this coating meets the supplementary lubrication requirements of A563 S1.
G Nuts overtapped for coating for use with 150 ksi/1040 MPa minimum tensile strength fasteners shall be proof load tested to a minimum of 175,000 psi after overtapping.
H Other metallic and non-metallic coatings may be used on 120 ksi/830 MPa minimum tensile fasteners upon agreement between the purchaser and user. Performance
requirements shall be specified by the purchaser and agreed to in writing. Coatings for 150 ksi/1040 MPa bolts must be qualified.
OS = over-size
Source: The table above is inspired by Table A1.1 from the ASTM F3125 Standard that you can purchase on the ASTM Website

With every structural fastener that is provided by Lightning Bolts comes a Mill Test Report that is sent through automatic compiling of technical datas at the moment of invoice.

Lightning Bolts also provides precise certificates of assembly for the bolts that we assemble inhouse and that will enable a full tracability of every component used in your set. Quality is our priority.

CERTIFICATE SAMPLE

On demand, we will also write a certification letter about the items contained in your order complying to the highest ASTM standards for the item descriptions contained in your purchase order.

A Rotational Capacity (ROCAP) Test is concluded on a structural bolt assembly (bolt, nut, and washer) to verify its performance under installation conditions and ensure it meets ASTM standards such as ASTM F3125 (A325/A490 bolts). This test assesses a bolt's ability to withstand tension and rotation without failure, preventing issues like thread stripping, galling, or inadequate tension development.

Since this test requires that each material lot of bolt and nut be tested individually, contractors will typically administer this test on the job site.

Situations When a Rotational Capacity Test is Necessary

  1. Quality Assurance in Procurement
    • When receiving a new batch of bolts from a supplier to verify compliance with ASTM requirements before distribution.
    • Ensuring that the lot meets pre-installation verification requirements.
  2. Project-Specific Requirements
    • When working on projects that mandate ROCAP testing per specifications (e.g., DOT, bridge, and infrastructure projects).
    • If an engineer or quality control inspector requests verification.
  3. Field Issues or Failures
    • If bolts exhibit installation difficulties, such as nuts failing to reach proper tension, stripping, or galling.
    • If users report bolts not performing as expected during torque application.
  4. Verification of Coating or Lubrication Effects
    • When dealing with galvanized bolts, as coatings can significantly alter friction and affect tightening behavior.
    • When verifying whether lubricant application (on mechanically galvanized or hot-dip galvanized bolts) is sufficient for proper tensioning.
  5. Requalification of Aged Stock
    • When bolts have been stored for extended periods and their lubricant may have degraded, requiring re-testing before use.
  6. Compliance with ASTM and AISC Requirements
    • ASTM F3125, AISC 360, and RCSC (Research Council on Structural Connections) require ROCAP testing as part of quality control for structural connections.

    7. Procedure

    1. Test Setup
      • Assemble the bolt, nut, and washer into a steel joint, ensuring that 3 to 5 threads are visible between the bearing surfaces of the bolt head and nut.
      • Apply an initial preload of at least 10% of the specified proof load.
      • Mark the initial nut position relative to the bolt.
    2. Tightening Rotation
      • Rotate the nut according to the specified requirements:
      Bolt Length (Relative to Diameter) Required Rotation
      ≤ 4 × diameter 2/3 rotation (240°)
      > 4 × diameter and ≤ 8 × diameter 1 rotation (360°)
      > 8 × diameter and ≤ 12 × diameter 1-1/6 rotation (420°)
      > 12 × diameter Test not applicable
    3. Post-Tightening Inspection
      • After applying the required rotation, disassemble the bolt assembly and inspect it for compliance.

Failure Criteria

The assembly fails the ROCAP test if any of the following occur:

  • ✅Installation Failure – The nut cannot be tightened to the required rotation.
  • ✅Removal Failure – The nut cannot be removed after reaching the specified rotation.
  • ✅Thread Shear Failure – Visual inspection shows thread damage upon removal.
  • ✅Torsional or Tension Failure – The bolt fractures or fails structurally.
🔹 Note: Bolt elongation between the nut and bolt head is normal and not considered a failure.
SAMPLE OF TEST HERE : ROCAP SAMPLE
TYPES OF F3125 GRADE A325 BOLTS
TYPE 1 Medium carbon, carbon boron, or medium carbon alloy steel. (STANDARD)
TYPE 2 Withdrawn November 1991.
TYPE 3 Weathering steel.
T Fully threaded A325. (Restricted to 4 times the diameter in length).
M Metric A325.
F3125 Grade A325, A490, F1852 & F2280 Matching Components
Type 1 Type 3
Recommended Nut and Washer
Plain Nut A563 DH A563 DH3
Suitable Alternative DH3, D, C, C3, A194 2H C3
Coated Nut A563 DH, A194 2H A563 DH3
Flat, Bevel or Thick washer if used F436-1 F436-3