8 catalogued sizes, dimensioned to ASTM F3125/F3125M Grade F1852 and F2280. Pick any row and the technical drawing redraws to it.
Tension-Control Structural Bolt Assemblies (TC / Twist-Off) to ASTM F3125/F3125M Grade F1852 and F2280 are catalogued in sizes M16 to M20. 8 sizes are held in the table below, and the technical drawing redraws to whichever row you select.
Standard
ASTM F3125/F3125M Grade F1852 and F2280
Size range
M16-M20
Catalogued sizes
8
Dimensions are nominal values from the governing standard. Confirm the tolerance class for your application before ordering.
Applications & Industries
Tension-Control Structural Bolt Assemblies are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from 1/2-13 to M20 (screw size).
Industries that specify Tension-Control Structural Bolt Assemblies
Industrial fabricationOne-pass structural assembly where repeatable tension matters more than later disassembly.
Steel erectionMatched structural bolt assemblies tensioned in beam, column and splice connections.
Bridge constructionSlip-critical steel joints where the final tension is set by the twist-off installation system.
Heavy transportTruck frames and chassis joints exposed to road vibration and cyclic load.
Food, pharma & cleanroomStainless assemblies that are washed down, where the finish matters as much as the strength.
Machine building & OEMThe default fastener on production equipment: covers, brackets, motor mounts and sub-assemblies tightened to a specified torque.
Typical applications
using the plain shank and heavy hex geometry for steel-to-steel joints
installing a matched bolt, nut and washer assembly with a controlled twist-off spline
setting structural tension without a separate torque reaction wrench on the nut
selecting F1852 or F2280 together with the required installation tension
joints where the property class is stated on the drawing
clamping two machined faces to a calculated preload
Service conditions to specify against
Marine and coastal
Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
High load
Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
Torque and preload
The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
Do not reuse the twisted-off spline or substitute a generic torque value for the grade-specific installation method.
Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.
Sends the selected values to the quote form below.
Request a Quotation for Tension-Control Structural Bolt Assemblies (TC / Twist-Off)
The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.
Dimensions & Specifications (ASTM F3125/F3125M Grade F1852 and F2280)
Every row below is a starting point for the customizer above — pick any size and the drawing will redraw to that row.
Tension-Control Structural Bolt Assemblies (TC / Twist-Off) (ASTM F3125/F3125M Grade F1852 and F2280) are a type of bolts used across industrial assembly. Below is the complete size table together with material, standard and application guidance.
What Are Tension-Control Structural Bolt Assemblies (TC / Twist-Off)?
Tension-Control Structural Bolt Assemblies (TC / Twist-Off) are bolts defined by ASTM F3125/F3125M Grade F1852 and F2280. They are selected by screw size and the dimensional characteristics shown below, and are available in a range of materials and finishes to suit the application and environment.
Materials & Finishes
Common materials include carbon steel (typically zinc plated or hot-dip galvanized), alloy steel in property classes 8.8, 10.9 and 12.9, and stainless steel A2 (304) or A4 (316) for corrosion resistance. Specify the material, property class and surface finish appropriate to your load and environment.
Pricing
Tension-Control Structural Bolt Assemblies (TC / Twist-Off) are supplied to order. Pricing starts from approximately US$2.50 per piece for standard sizes in carbon steel; final pricing depends on size, material, finish and order quantity (MOQ applies). Submit your exact configuration with the quote form above.
Inside the plant
Manufactured in our own plant
This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.
01
Cold heading
Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.
Head dimensions and under-head radius checked at set-up and per shift.
02
Thread rolling
Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.
Go / no-go ring gauges to ISO 965 tolerance class 6g.
03
Heat treatment
Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.
Core hardness and tensile tested per lot to ISO 898-1.
04
Surface treatment
Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.
Coating thickness and neutral salt spray hours to ISO 9227.
Frequently Asked Questions
What is the controlling standard for Tension-Control Structural Bolt Assemblies (TC / Twist-Off)?
Tension-Control Structural Bolt Assemblies (TC / Twist-Off) are manufactured to ASTM F3125/F3125M Grade F1852 and F2280. The dimensional values on this page follow that standard.
Which sizes of Tension-Control Structural Bolt Assemblies (TC / Twist-Off) does Engineering Hardware supply?
The table on this page lists 8 sizes for Tension-Control Structural Bolt Assemblies (TC / Twist-Off), ranging from 1/2-13 to M20. Sizes outside the table can be quoted on request.
In which materials are Tension-Control Structural Bolt Assemblies (TC / Twist-Off) supplied?
Tension-Control Structural Bolt Assemblies (TC / Twist-Off) are supplied in carbon steel in property classes 8.8 / 10.9 / 12.9 and stainless A2 (304) / A4 (316), with finishes including zinc plating, hot-dip galvanizing and black oxide. Choose material and finish to suit the load and the service environment for Tension-Control Structural Bolt Assemblies (TC / Twist-Off).
How do I request a quotation?
Use the parametric drawing on this page to set the exact configuration (size, material, finish) and click "Request this configuration" — a specialist from Engineering Hardware will respond within one business day.
Need a fastener quote or a spec sheet?Message our engineers on WhatsApp — send a drawing or DIN number and get pricing back fast.Start WhatsApp Chat →
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