To measure accurate preload, service load and overload of bolted assemblies

For maximum uniformity, efficiency and reliability in bolted assemblies

For effective research, testing and manufacturing of bolted assemblies

Allowable Loads
Allowable loads for Strainsert Hex Head Cap Screws, as tabulated below, are based on approximately 70% Yield Strength of the threads, in pounds.
Load Capacity Lbs.
Screw Dia. Load
1/4-20NC 900
5/16-18NC 1500
3/8-16NC 2200
1/2-13NC 4000
5/8-11NC 6500
3/4-10NC 10000

Each cap screw is calibrated to above indicated load as part of quality control procedure. See calibration section for additional calibration certification.

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Unit of Measure



N/A Aluminum Alloy, 2024-T4


N/A Rockwell B54 Minimum

Ultimate Tensile Strength

N/A 55,000 psi Minimum; 60,000 psi average


N/A Class 2A, rolled

Thread Length

N/A 2-diameters + 1/4 inch full threads + 3/16 inch maximum imperfect threads.


N/A Load & Unload Calibration Load Only Calibration (Standard)

Performance Specs

Gages Type

N/A Metal Foil

Gage Factor (Nominal)

N/A 2.00


N/A ±1% of Allowable Load


N/A ±0.1% FS


N/A 350-ohm (Standard) FB: 12V (Maximum)
120-ohm FB: 3V (Maximum)

Output Signal (Nominal)

N/A FB: 3.0 mv/V, approx.


N/A Full Bridge Strain Gage Circuit (Standard)

Bridge Resistance (Nominal)

N/A 120 Ω 350 Ω (Standard)

Service Temperature

N/A 150°F (Standard) 250°F (Max.)

General Information

N/A Strainsert fasteners utilize an exclusive internal gaging method (U.S. Patent #2,873,341) to indicate bolt tension due to preload and subsequent service loads with strain gage accuracy. They are the first fasteners to provide a means for accurate, independent inspection of an assembled bolt for preload, thereby enhancing the structural integrity and reliability of both the bolt and the assembly.


  • Measurement of preload induced in fasteners
  • Accurate tightening of fasteners within 1% of induced load
  • Uniform tightening of fasteners in a bolt pattern