Bolt Tensioner Application

  • 50% Tool Coverage

    50% Tool Coverage

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    100% Tool Coverage

Important formula

Residual Bolt Load Bolt Stress x Bolt Tensile Stress Area
(Bolt Stretch x Modulus of Elasticity x Bolt Tensile stress area)/ Effective Length.
Bolt Tensile Stress Area (3.14 x D X D) / 4 (D is smallest Stress Dia of Bolt)
% of Yield Strength (Bolt Stress Required / Yield Strength of bolt) x 100
Hydraulic Pressure (Residual Bolt Load x Load Relaxation Factor) / Hydraulic Area of Load Cell.
Load Relaxation Factor 1.01 + (Bolt Size (Dia.) / Effective Length) or 1.1 which ever is greater.

Basic Calculation and Working

  • Calculate Bolt Residual Load: Residual Load can be calculated from known stress or bolt stretch requirement.
  • Calculate Load Relaxation factor using Bolt Dia and Effective Length. It can be calculated from below formula / Chart.
  • Calculate application hydraulic load.
  • Calculate hydraulic pressure for required hydraulic load.
  • Select Tensioning Procedure. (25%, 50%, 100%...etc.)
  • Calculate pass load as applicable. (Max applied load should never exceed 95% bolt yield strength).

Bolt Tensioner App Graph

Useful Conversions

Area 1 millimeter2 (mm2 ) = 0.00155 inch2
1 centimeter2 (cm2 ) = 0.155 inch2		 1 inch2 = 645.16 mm2
1 inch2 = 6.4516 cm
Load (Force) 1 Metric Ton (mt) = 1.10231 Short Ton (US)
1 Kilo Niwton, kN = 224.8089 lb
1 Metric Ton (mt) = 9.8066 kN		 1 mt = 0.9842 Long Ton (UK)
1 kN = 0.0958 mt
1 st = 0.0958 mt
Pressure 1 Megapascal (MPa) = 10 Bar
1 Kg per cm2 (Kg/cm2 ) = 0.98066 Bar		 1 bar = 14.5037 psi
1 bar = 1.0197 Kg/cm2
Pressure 1 Megapascal (MPa) = 10 Bar 1 bar = 14.5037 psi