Torshear Type High Strength Tension Control TC Bolt

Torshear Type High Strength Bolt Assembly

TC Bolt | Tension Control Bolt | Grade 10.9S / 12.9S · GB/T 3632-2024 /High Strength Bolt / Steel Structure Fastener

Standard	GB/T 3632-2024 (ISO 898-1 equivalent)
Diameter range	M16 ~ M30 (M16, M20, M22, M24, M27, M30)
Length range	40mm ~ 220mm (custom available)
Property class	10.9S / 12.9S
Surface finish	Black oxide, phosphating, zinc plating, hot dip galvanized, Dacromet
Material	20MnTiB, 35VB, 42CrMo, ML40CrMo
Assembly content	1 bolt + 1 nut + 1 washer
Fastening method	Twist-off (splined tail breaks at target torque)

Product Overview

Tarco Torshear type high strength bolt (TC bolt / Tension Control Bolt) is a preloaded structural fastener widely used in steel construction. Its distinct feature is the “twist-off tail” — during installation with a special electric shear wrench, the splined tail (twist end) shears off at a predetermined torque, indicating that the required pretension has been achieved.

This mechanism eliminates the need for complex torque-angle control required by traditional hex head bolts, offering higher installation efficiency, reliable pretension, and visual inspection (simply check whether all tails are sheared off). Manufactured strictly according to GB/T 3632-2024 “High strength bolt assemblies for steel structures”, property classes 10.9S and 12.9S. Widely used in high-rise buildings, long-span stadiums, bridges, industrial plants, and tower structures.

Key Advantages

🔧 Twist-off Technology

Precise pretension without torque coefficient calibration; the splined tail shears off automatically at final tightening — increases erection speed by over 30%.

📋 Visual Quality Control

Inspection is intuitive: all tails must be sheared off. Drastically reduces risk of under-torquing or missing bolts.

🏗️ High Load Capacity

Grade 10.9S tensile strength ≥1000MPa, Grade 12.9S ≥1200MPa. Ideal for dynamic and heavy loads in seismic zones and bridges.

🌍 Global Standards

Complies with GB/T 3632, also meets ISO 898, ASTM F1852 (alternative), EN 14399, ensuring global project acceptance.

Technical Specifications & Sizes

M16 Pretension ≈ 110 kN; M20 Pretension ≈ 170 kN ; M22 Pretension ≈ 210 kN ; M24 Pretension ≈ 250 kN; M27 Pretension ≈ 320 kN ; M30 Pretension ≈ 390 kN;

※ Values based on Grade 10.9S per GB/T 3632. Custom lengths available upon request.

📐 Common Size Chart

Thread Size	Pitch (mm)	Length Range (mm)	Property Class
M16	2.0	40~150	10.9S / 12.9S
M20	2.5	45~180	10.9S / 12.9S
M22	2.5	50~200	10.9S / 12.9S
M24	3.0	55~220	10.9S / 12.9S
M27	3.0	60~220	10.9S / 12.9S
M30	3.5	65~220	10.9S / 12.9S

Core Mechanical Performance

🔩 Pretension Reliability

Each batch tested per GB/T 3632 for assembly preload consistency, ensuring low standard deviation and stable clamping force.

⚙️ Wedge Load Test

100% wedge load test available; bolts withstand wedge load without fracture, meeting grade 10.9/12.9 requirements.

💪 Hardness & Impact Toughness

Core hardness HRC 33~39; Charpy V-notch impact energy ≥27J at -20°C, suitable for cold regions.

🛡️ Corrosion Resistance

Options: Dacromet, hot-dip galvanized, phosphating, zinc plating. Salt spray test up to 500h+ for outdoor/coastal environments.

Main Applications

🏢 High-rise Steel Buildings 🌉 Highway & Railway Bridges 🏭 Industrial Plants / Warehouses 🗼 Transmission Towers & Telecom Masts ✈️ Airport Terminals & Stations
🏟️ Stadiums & Convention Centers 🏗️ Cranes & Heavy Machinery 🚄 Rail Transit Infrastructure 🏭 Boiler Steel Structures 🏞️ Pipe Supports & Racks

Torshear bolts are ideal for friction-type or bearing-type connections in structural steel projects, ensuring safety and stability under static and dynamic loads.

Installation Guidelines & Code Compliance

🔨 Installation method: Two-step tightening — snug-tight + final tightening. Snug-tight torque calculated per Tc = 0.065 × Pc × d. Final tightening performed with electric torshear wrench until the splined tail is completely sheared off. Inspection is visual: all tails must be broken.

📖 Applicable standards: Product manufactured to GB/T 3632-2024; installation and acceptance follow JGJ 82-2011 (China) or equivalent international guidelines (ASCC, RCSC). Each assembly includes one bolt, one nut, and one washer. Only one washer required under the turned nut element.

⚠️ Critical notes: Final tightening must be completed within 24 hours after snug-tight. Never hammer off the tail instead of using a shear wrench. Ensure proper washer placement. Torshear bolts are single-use — do not reuse after installation.

Why Choose Our Torshear High Strength Bolts?

✅ Stringent quality control: In-house cold forging, heat treatment, and advanced testing equipment.
✅ Fully certified: ISO 9001 certified; third-party test reports from national fastener inspection centers available.
✅ Proven track record: Used in landmark skyscrapers, long-span bridges, airports, and stadiums globally. Exporting to North America, Europe, Southeast Asia, Middle East.
✅ Customization: Non-standard lengths, special coatings, and specific material grades to meet unique project requirements.
✅ Technical support: From selection guidance to on-site installation assistance, ensuring project success.

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