Interactive bolt torque calculation for PED certified flange and valve joints.
Use LOKRON's calculator to estimate tightening torque from bolt size, yield strength, preload percentage, and friction condition for industrial stud bolting in pressure-boundary service.
Coating / Lubrication Condition
Target Yield Percentage
Engineering preload factor eta applied to material yield strength.
Real-time output based on bolt geometry, yield target, and friction condition.
LOKRON's Genuine Xylan PTFE coating lowers friction scatter at the nut-bearing interface, allowing more of the applied torque to convert into useful preload. That can reduce wasted friction torque by up to 60% versus dry assembly while helping prevent galling, thread seizure, and inconsistent clamp load in high-pressure valve boundary joints.
Supported PED-certified bolt grades
This calculator currently covers ASTM A193 B16, B7, B7M, B8 Class 1, B8 Class 2, B8M Class 1, B8M Class 2, plus ASTM A320 L7 and L7M within the calculator size set of 1/2 inch through 1 inch nominal diameter.
Torque formula used in this calculator
The tool applies the classic industrial torque-tension relationship used in bolted-joint practice. Target preload is calculated from tensile stress area, minimum yield strength, and selected yield percentage, then converted into torque through the selected K-factor.
Need coated stud bolts matched to your target preload window?
LOKRON supplies PED-certified ASTM A193 and A320 bolting packages with controlled coating conditions, EN 10204 traceability, and application support for pressure-boundary assemblies.
Bolt torque calculator FAQ
Which PED-certified grades are included?
The current calculator includes ASTM A193 B16, B7, B7M, B8 Class 1, B8 Class 2, B8M Class 1, B8M Class 2, and ASTM A320 L7 and L7M.
What torque equation is used?
The calculator uses the classic torque-tension equation T = K × F × d with preload F calculated from tensile stress area multiplied by minimum yield strength and the selected target yield percentage.
Why does PTFE coating change the torque result?
A lower K-factor means less applied torque is lost to friction, so more of the input torque converts into useful preload. PTFE-coated assemblies therefore reach the same preload at lower torque than dry steel joints.