High Strength Friction Grip (HSFG) Bolts | Structural Bolts

HSFG / Structural Bolts - IS | ISO

TRM offers a variety of products and information you may find useful, so feel free to explore.

HSFG, or High Strength Friction Grip, is designed differently from traditional bolts. A conventional bolt prevents the separation of plates in a connection by enduring shear stress along the bolt shank, while an HSFG holds the plates together so tightly that they cannot move past one another.

The notable advantages of HSFG bolted connections include increased stiffness and the capacity to resist alternating forces. Additionally, their performance under fatigue loading is superior compared to bearing bolted connections. However, one must consider the increased costs associated with HSFG bolted connections.
The bolts are tensioned to a precise level ensuring that the transverse load across the joint is countered by the friction between the plates, rather than relying on the shear strength of the bolt shank. Although HSFG bolts offer benefits, they are rarely used due to their cost and in many applications, they are unnecessary.
In essence, the friction created between the plates matches the load imposed by the supported beam's weight.
HSFG bolts are widely employed in structures susceptible to vibrations or fluctuating loads. To prevent plate slippage, careful preloading of the bolt is crucial. Moreover, surrounding areas must be clean and unpainted, and the bolt must be tightened to an exact specification.
Overall, HSFG bolts are high-strength structural bolts preloaded to create defined tension within the bolt shank, effectively ensuring no slip occurs between the plates, thereby maintaining the integrity of your fasteners.

If you wish to deepen your knowledge, please visit our site at Friction Bolt.

     

Annexure - I - Specifications - Table 1

Dia

• M16x2
• M20x2.5
• M22x2.5
• M24x3

s

• 15.30 - 16.70
• 19.16 - 20.84
• 21.16 - 22.84
• 23.16 - 24.84

d

• 26.16 - 27.00
• 33.00 - 34.00
• 35.00 - 36.00
• 40.00 - 41.00

h

• 9.25 - 10.75
• 11.60 - 13.40
• 13.10 - 14.90
• 14.10 - 15.90

t < 100

• 31
• 36
• 38
• 41

l > 100

• 38
• 43
• 45
• 48

Proof Load in N 

• 8.8S
• 10.9S

Mechanical Property: 8.8 or 10.9 as per ISO 898, IS (3)

Threads: ISO Metric 6g Class as per ISO 965, IS

Dia

• M27x3
• M30x3.5
• M36x4

s

• 26.16 - 27.84
• 29.16 - 30.84
• 35.00 - 37.00

d

• 45.00 - 46.00
• 49.00 - 50.00
• 58.80 - 60.00

h

• 16.10 - 17.90
• 17.65 - 19.75
• 21.45 - 23.55

t < 100

• 44
• 49
• 56

l > 100

• 51
• 56
• 63

Proof Load in N 

• 8.8S
• 10.9S

Annexure-II - Selection Chart for Bolt Length & Weight (kg./ pcs.) - Table 2

Dia

• M16
• M20
• M22
• M24

Length

Grip Length

• Weight
• Grip Length
• Weight
• Grip Length
• Weight
• Grip Length
• Weight
• Grip Length
• Weight

Various lengths and corresponding weights (from 40mm to 250mm).

Dia

• M27
• M30
• M36

Length

Grip Length

• Weight
• Grip Length
• Weight
• Grip Length
• Weight

Various lengths and corresponding weights (from 40mm to 300mm).

High Strength Friction Grip Bolts - Structural Bolt Manufacturer

What is an HSFG Bolt

High-Strength Friction Grip Bolts, or HSFG bolts, are engineered to provide exceptional strength, exceeding the load capacity of standard bolts with similar specifications. The term 'friction grip' uniquely emphasizes that these bolts utilize pre-tensioning during the tightening process to generate substantial frictional forces perpendicular to the screw direction, thus enabling effective shear force transmission during the connection.

Structural Differences of HSFG Bolts

While HSFG bolts share a similar shape and connection framework with ordinary bolts, the critical difference lies in how they operate. Regular bolts depend on the rod’s compression and shear resistance to transfer shear forces, with little regard for the pre-tension created during tightening. In contrast, HSFG bolts exert considerable pre-tension to generate compression forces between connected surfaces, leading to significant friction forces that play a vital role in shear force transfer during connections.

Contact us to discuss your requirements for a Mesh Bolt. Our knowledgeable sales team is ready to help you find the best options for your needs.