Note: In 2016, specifications A325 and A490 were officially withdrawn by ASTM and replaced by ASTM F3125. A325, 144 and A490 heavy hex structural bolts are now grades under the new F3125 specification. Summaries of the now obsolete A325 and A490 specifications remain on our site for reference purposes only.
This specification covers the chemical, physical and mechanical requirements for structural bolts manufactured from steel and alloy steel, in two strength grades, two styles and two types. This specification is a consolidation of and replacement for six ASTM standards ranging from 1/2″ through 1-1/2″ diameter: A325, A325M, A490, A490M, F1852 and F2280. The main difference between this standard and the older, existing standards is that A325s from 1-1/8” to 1-1/2” now have the same mechanical requirements as A325s 1” and under. Previously the larger bolts had slightly lower requirements.
F3125 Bolt Types
Grade
Min Strength, Tensile
Type
Style
A325
120ksi min
1 or 3
Heavy Hex Head
A325M
830MPa min
1 or 3
Heavy Hex Head
F1852
120ksi min
1 or 3
Twist-Off/TC
A490
150-173ksi
1 or 3
Heavy Hex Head
A490M
1040MPa
1 or 3
Heavy Hex Head
F2280
150ksi
1 or 3
Twist-Off/TC
144
144ksi
1 or 3
Heavy Hex Head
144
144ksi
1 or 3
Twist-Off/TC
* Type 1 – 120ksi - carbon, carbon boron, alloy, or alloy boron steel * Type 1 – 150ksi – alloy or alloy boron steel * Type 3 – weathering Steel
Chemical Requirements – Type 1
Heat Analysis
120ksi and 144ksi, %
150ksi, %
Carbon
0.30 – 0.52
0.30 – 0.48*
Manganese
0.60 min
0.60 min
Phosphorus
0.035 max
0.035 max
Sulfur
0.040 max
0.040 max
Silicon
0.15 – 0.30
-
Boron
0.003 max
0.003 max
Copper
-
-
Nickel
-
-
Chromium
-
-
Molybdenum
-
-
*Carbon 0.35-0.53% for 1-1/2” A490/150ksi bolts
Chemical Requirements – Type 3
Heat Analysis
120/144ksi, % Comp A
120/144ksi, % Comp B
120/144ksi, % Index
150ksi, % Index
Carbon
0.33 – 0.40
0.38 – 0.48
0.30 – 0.52
0.30 – 0.53
Manganese
0.90 – 1.20
0.70 – 0.90
0.60 min
0.60 min
Phosphorus
0.035 max
0.035 max
0.035 max
0.035 max
Sulfur
0.040 max
0.040 max
0.040 max
0.040 max
Silicon
0.15 – 0.30
0.30 – 0.50
Copper
0.25 – 0.45
0.20 – 0.40
0.20 – 0.60
0.20 – 0.60
Nickel
0.25 – 0.45
0.50 – 0.80
0.20 min*
0.20 min*
Chromium
0.45 – 0.65
0.50 – 0.80
0.20 min
0.20 min
Molybdenum
0.06 max
0.10 min*
0.10 min*
*Either Nickel or Molybdenum must be present in the amount specified*Corrosion Index based on ASTM Guide G101
F3125 Mechanical Properties
Grade
Tensile, ksi
Yield, ksi min
Elongation, % min
RA, % min
120ksi (A325/F1852)
120 min
92
14
35
144ksi (F3148)
144 min
115
14
35
150ksi (A490/F2280)
150-173
130
14
40
F3125 Marking Requirements & Matching Components
120ksi, Type 1
120ksi, Type 3
144ksi T-1
144ksi T-3
150ksi, Type 1
150ksi, Type 3
Marking
A325
A325
144
144
A490
A490
Nut, Plain
A563 DH
A563 DH3
A563 DH
A563 DH3
A563 DH
A563 DH3
Nut, Coated
A563 DH
A563 DH3
A563 DH
N/A
A563 DH
A563 DH3
Washer
F436-1
F436-3
F436-1
F436-3
F436-1
F436-3
* A194 2H nuts are an acceptable substitute for A563 DH nuts * Suitable plain finish nut alternatives can be found in the full F3125 text * Supplementary requirements S1 and S2 have special marking requirements.
F3125 Permitted Coatings
120 ksi/830 Mpa and 144 ksi Bolt Assemblies*
Commonly Applied Coatings
Grade or Class
F2329
Hot Dip Galvanized / 50 μm
B695
Class 55
Other Coatings
Classification codes
Corrosion
Appearance
Coefficient of friction
F3393
D
1
R**
150 ksi/1040 Mpa Bolt Assemblies*
Qualified Coatings
Classification codes
Corrosion
Appearance
Coefficient of friction
F3393
D
1
R**
* Coatings for Twist-Off style bolt assemblies shall be agreed upon between the producer, supplier and user, and are not permitted except when applied under the direction of the manufacturer. The coefficient of friction classification code does not apply to Twist-Off style bolt assemblies. ** Specification F3393 is a consolidation and replacement of three ASTM standards which included qualified coatings F1136/F1136M Bolt & Washer Grade 3, Nut Grade 5, F2833 Grade 1, and F3019/F3019M Grade 4.
F3125 Nut Overtap Allowances
Size
F2329 and B695, in
F3393
½-13
0.018
0.009
5/8-11
0.020
0.010
¾-10
0.020
0.010
7/8-9
0.022
0.011
1-8
0.024
0.012
1-1/8-7
0.024
0.012
1-1/4-7
0.024
0.012
1-3/8-6
0.027
0.014
1-1/2-6
0.027
0.014
* Hot-dip galvanized and F3393 nuts are tapped after coating. B695 mech galv is applied after nut tapping * Nuts overtapped for use with 150ksi/A490 bolts shall be proof load tested to 175ksi minimum after overtapping
F3125 Supplemental Requirements
S1
A325/120ksi bolts up to 4x the diameter threaded full length. Mark A325T
S2
Alternate head geometry or thread length. Mark A325S or A490S
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