ASTM · Structural connections

Structural bolts
for demanding connections

ASTM specifications for steel structures, bridges, industrial plants, towers, power generation and heavy machinery.

Explore specifications Check availability

ASTM F3125

Structural connection with heavy hex bolt assemblies and tension control bolts

Heavy hex and TC

Up to 150 ksi

F3125

Main family

ASTM F3125

Configurations

Heavy hex and TC

Range covered

60 to 150 ksi

Dimensional standards

ASME B18.2.1 / B18.2.6

ASTM F3125 family

Four grades for structural connections.

A325 and A490 use a heavy hex head. F1852 and F2280 are TC assemblies whose spline indicates the installation tension.

Heavy hex head

Grade A325

High-strength bolt for steel structure connections, industrial plants and applications under heavy loads.

Minimum tensile: 120 ksi (827 MPa) for diameters ≤ 1″; 105 ksi (724 MPa) for diameters > 1″ up to 1½″
Yield / reference: 92 ksi minimum · ASME B18.2.6

Heavy hex head

Grade A490

Quenched and tempered alloy steel for demanding structural connections in bridges, buildings, plants and power stations.

Minimum tensile: 150 ksi (1040 MPa)
Yield / reference: — · ASME B18.2.6

TC · Tension control

Grade F1852

Supplied as an assembly with nut and washer. The spline shears off once the correct installation tension is reached.

Minimum tensile: 120 ksi
Yield / reference: 92 ksi · TC equivalent of A325

TC · Tension control

Grade F2280

High-strength tension control assembly for bridges and other structures; the spline confirms the installation tension.

Minimum tensile: 150 ksi
Yield / reference: 130 ksi · TC equivalent of A490

Selection by application

Other ASTM specifications available.

Carbon steel · Grades A and B

ASTM A307

Carbon steel bolts and studs. Grade A covers general use; Grade B is intended for flange bolts and assemblies with particular requirements.

Dimensional range: Diameters from ¼″ to 4″ · ASME B18.2.1
Tensile strength: Grade A: 60 ksi (414 MPa) · Grade B: 60–100 ksi (414–690 MPa)

ASTM A307 Grade A bolt with black finish

ASTM A307 Grade A bolt, hot-dip galvanized

ASTM A307 Grade B bolt with electroplated zinc

Diameters from ¼″ to 4″

ASTM A354

General-purpose fasteners and critical applications: towers, telecommunications, flanges, mining, power and heavy machinery.

Strength: BC: 125 ksi (862 MPa) · BD: 150 ksi (1040 MPa) up to 2½″; 140 ksi (965 MPa) above 2½″
Reference: Grades BC and BD

Diameters from ¼″ to 3″

ASTM A449

Heat-treated bolts, hex cap screws and studs for mechanical and industrial applications requiring more strength than ASTM A307.

Strength: 120 ksi (827 MPa) up to 1″ · 105 ksi (724 MPa) above 1″ up to 3″
Reference: ASME B18.2.1

Grades A, B and C

ASTM A394

Steel bolts for transmission towers, telecommunications and lattice structures, in black finish or hot-dip galvanized.

Strength: Grade A: 60 ksi · Grade B: 105 ksi · Grade C: 120 ksi
Reference: ASME B18.2.1 or ASME B18.2.6

Technical notes

Hardness, diameter and coating must be reviewed as part of the complete fastening assembly.

ASTM A354 Grade BC: hardness of 24–35 HRC. ASTM A354 Grade BD: hardness of 33–39 HRC.
ASTM A449: hardness of 24–34 HRC for diameters ≤ 1″ and 22–32 HRC for diameters > 1″.
For ASTM A449, electroplated coatings must take into account ASTM F1941/F1941M and ASTM B850 practices for hydrogen embrittlement relief.

Technical support

Need to validate the structural standard for your project?

Send us the ASTM standard, diameter, length, finish, quantity and application on WhatsApp. Our technical team will review the requirement with you.