As a result, we deliver factory-direct pricing, consistent mechanical properties, and fast delivery. Similarly, this applies to all your steel bridge, high-rise building, and heavy steel structure projects.

In addition, we produce these high strength tension control bolts to comply with ASTM F1852 and ASTM F2280. Meanwhile, these grades are also covered under the unified ASTM F3125 standard. Therefore, engineers and fabricators rely on them for preloaded structural steel connections worldwide.

ASTM F1852 & F2280 Tension Control Bolt — Grade & Strength Specifications

To begin with, we manufacture our TC bolts in two primary grades. Specifically, the table below compares their mechanical properties and standard equivalents.

Furthermore, F1852 offers a strength equivalent to that of Grade A325, and F2280 offers a strength equivalent to A490.[reference:8] Additionally, we also supply Grade S10T per JSS II 09, the Japanese standard for torsional shear type high strength bolts.[reference:9]

Material & Coating Specifications for Tension Control Bolts

• To begin with, we use ML40Cr alloy steel as the standard base material for our torshear bolts.
• Moreover, we match each bolt with a SWRCH45K nut and a 45# hardened washer to form a complete assembly.
• Additionally, we offer hot-dip galvanized (HDG), Dacromet, zinc flake coating, and black oxide surface treatments.
• Furthermore, our TC bolt assemblies comply with ASTM F1852, ASTM F2280, EN 14399-10 (System HRC), and GB/T 3632.
• For special orders, we supply weathering steel (Type 3) TC bolts for atmospheric corrosion resistance.
• Finally, we offer OEM & ODM — we customize bolt diameter, length, head marking, coating, and packaging according to your project specifications.

How Tension Control Bolts Work — Spline Shear-Off Technology

In fact, the tension control bolt is a high-strength structural fastener with a unique tension control mechanism. Furthermore, it has a reduced section (breakneck) at the end of the thread followed by a splined end (pintail).[reference:10]

To begin with, the spline is gripped by the inner socket of a special electric shear wrench. Meanwhile, the outer socket engages the nut. Then, when the wrench rotates, the nut tightens while the spline holds the bolt stationary.

Next, the breakneck shears off at a pre-calibrated torque. Consequently, the tension value related to the shearing-off torque becomes the final preload achieved in the bolt.[reference:11] Therefore, proper bolt tension is confirmed by the shear-off spline — no torque gauges are required.[reference:12]

Key Installation Advantages of TC Bolts

• First, One-Person Installation — a single operator can install the bolt from one side of the structure using an electric shear wrench.
• Second, Visual Inspection — the sheared-off spline provides immediate visual confirmation of correct tension.
• Third, No Torque-Controlled Tools — the bolt has its own built-in torque control device, so you need no calibrated wrench.[reference:13]
• Fourth, Reduced Noise — the shear wrench produces substantially less installation noise than impact wrenches.
• Finally, Cost Savings — faster installation reduces labor time and overall project costs.

About Our Factory — Direct Manufacturer of Torshear Type TC Bolts

In fact, Tarco Industry operates a modern manufacturing facility. Specifically, we dedicate it to the production of tension control bolts, torshear bolts, and high strength structural fasteners.

Furthermore, we complete every step in our own factory. This includes wire drawing, cold forging, thread rolling, heat treatment, coating, and assembly. Consequently, we do not outsource production. We do not act as a middleman.

In addition, we equip our factory with advanced hot forging machines and automated thread rolling lines. As a result, we produce ASTM F1852 and F2280 compliant TC bolts with consistent breakneck dimensions and reliable shear-off torque.

Therefore, whether you need F1852 or F2280 TC bolts, Tarco Industry can produce them directly for you.

Factory Direct Advantages

• First, we are a Manufacturer, Not a Trader. You buy directly from Tarco Industry production lines, eliminating middleman markups.
• Second, we handle In-House Production. We produce bolts, nuts, and washers all under one roof for full quality control.
• Third, we welcome OEM & ODM. We customize bolt dimensions, head markings, coatings, and packaging.
• Fourth, we maintain Bulk Production Capacity — stable output for large steel bridge and infrastructure orders.
• Finally, we provide Factory Price — competitive direct pricing for steel fabricators and EPC contractors.

Why Choose Our Torshear Type TC Bolts?

• For example, our bolts offer Built-In Tension Control. The breakneck shears off at a pre-calibrated torque, ensuring correct preload every time.
• In addition, they provide One-Side Installation. A single operator can install from one side using an electric shear wrench.
• Moreover, they feature Immediate Visual Verification. The sheared-off spline confirms proper tension without torque gauges.
• Furthermore, they ensure Full ASTM Compliance. Our TC bolts meet ASTM F1852, F2280, and F3125 requirements.
• As a result of their High Preload Capacity, they achieve the minimum preload required for slip-critical connections.
• Finally, we provide Direct Factory Support. Tarco Industry provides technical guidance, samples, and custom production.

How to Install Torshear Type TC Bolts

1. First, insert the bolt through the aligned holes in the connecting steel members.
2. Then, attach the nut and washer. Place the hardened washer under the nut and snug-tighten the assembly.
3. Next, fit the shear wrench. Engage the inner socket over the bolt spline and the outer socket over the nut.[reference:14]
4. After that, activate the wrench. The wrench rotates the nut while holding the spline, tightening the bolt to the specified preload.
5. Finally, verify the shear-off. The spline shears off at the calibrated torque, confirming that proper tension has been achieved.

Applications & Industries for Tension Control Bolts

• For instance, in steel bridge construction, contractors use our TC bolts for main girder splices, crossbeam connections, and bearing assemblies.[reference:15]
• Also, in high-rise buildings, they secure beam-to-column connections requiring precise preload control.
• In addition, for stadia and roof trusses, they connect bespoke steel geometries in long-span roof structures.[reference:16]
• Furthermore, in wind energy towers, they enable turbine heights in excess of 148m for more efficient power generation.[reference:17]
• Lastly, in rail and infrastructure projects, they are preferred for site connections of new rail bridges and bridge strengthening.[reference:18]

Quality Assurance & Certifications

Furthermore, Tarco Industry manufactures our Torshear Type TC Bolts under strict quality control. Specifically, they comply with ASTM F1852, ASTM F2280, and ASTM F3125.

As a result, we perform dimensional inspection, tensile testing, hardness testing, and shear-off torque verification. Moreover, we test every production batch before shipment.

• Additionally, we offer certifications including ISO 9001, CE, and SGS.
• Similarly, our production capacity reaches 500 tons per month.
• Also, we set the MOQ at 5 tons (negotiable for sample orders).
• In terms of packaging, we offer cartons on pallets or wooden crates with custom marking.
• Finally, we deliver within 20–30 business days after order confirmation.