Product Introduction — Torsional Shear Type High-Strength Bolt for Steel Structures 

The torsional shear type high-strength bolt assembly for steel structures is a specialized fastener produced according to the GB/T 3632 standard, consisting of a bolt, a nut, and a washer. The bolt material is low-alloy high-strength steel 20MnTiB, with a property class of 10.9S. Its most distinctive feature is the spline (crown) break-off end on the bolt tail. During installation, a dedicated electric wrench is used, and the spline head automatically breaks off once the specified preload is reached, serving as a clear indication of tightening completion. This ensures accurate and stable preload in the bolt assembly and is widely used for on-site installation of critical steel structures.

One Product Features

High strength: Property class 10.9S, with tensile strength reaching above 1040 MPa, providing strong load-bearing capacity.

Torsional shear control: The spline break-off end design, which automatically separates after the wrench applies the specified break-off torque via a dedicated wrench — no torque wrench is needed during construction, making operation simple.

Complete bolt assembly: Bolts, nuts, and washers are supplied as a matched set according to the standard, with a stable torque coefficient ensuring minimal preload scatter.

Premium material: Made from 20MnTiB low-alloy steel, which after heat treatment offers high strength, good toughness, and excellent hardenability.

Surface treatment: Generally phosphatized or blackened, providing certain rust resistance for convenient storage and installation.

Two Product Advantages

High construction efficiency: Tightened with a dedicated electric wrench; the spline head breaking off indicates completion — no repeated torque measurement is needed, greatly improving installation speed.

Reliable quality: Preload is controlled by break-off torque, effectively avoiding hazards caused by under-tightening or over-tightening common with ordinary high-strength bolts, ensuring stable connection quality.

Intuitive inspection: Whether the spline head has broken off is immediately visible, facilitating on-site quality acceptance and reducing manual inspection workload.

Good safety: High-strength connections can withstand significant dynamic loads and alternating loads, suitable for earthquake-resistant, wind-resistant, and other critical structures.

Economical and reasonable: Although the unit price is slightly higher than ordinary bolts, construction is fast and inspection costs are low, resulting in obvious overall economic benefits.

Three Application Areas

Building steel structures: Beam-column connection nodes in high-rise buildings, large-span venues, industrial factory buildings, and other steel structures.

Bridge engineering: Member splicing and joint connections in highway and railway steel bridges.

Tower and mast structures: Electric power towers, communication towers, wind turbine towers, etc.

Cranes and machinery: Steel structure connections in large cranes, port machinery, and mining equipment.

Other critical steel structures: Applicable to any steel structure engineering that requires high-strength, high-reliability