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Suggested tightening torque values

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Suggested Tightening Torque Values to ​Produce Corresponding Bolt Clamping Loads

Suggested Tightening Torque Values to Produce Corresponding Bolt Clamping Loads
Click to enlarge
  1. Tightening torque values are calculated from the formula T = KDP, where T= tightening torque. lb-in. K=torque-friction coefficient; D = nominal bolt diameter. in; and P = bolt clamp load developed by tightening. lb.
  2. Clamp load is also known as preload or initial load in tension on bolt. Clamp load (lb) is calculated by arbitrarily assuming usable bolt strength is 75% of bolt proof load(psi) times tensile stress area(sq in.) of threaded section of each bolt size. Higher or lower values of clamp load can be used depending on the application requirements and the judgement of the designer.
  3. Tensile strength (min psi) of all Grade 7 bolts is 133,000. Proof load is 105,000 psi.
  4. Tensile strength (min psi) of all Grade 8 bolts is 150,000 psi. Proof load is 120,000 psi. Ref.:Fastening Reference, Machine Design, Nov 1977.

​​Bolt Clamping Force vs. Tightening Torque for Unlubricated Steel Bolts

Picture
Click to enlarge

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  • Home
  • Spring Selection
    • Precision Belleville Springs >
      • .236 to .394
      • .472 to .492
      • .551 to .591
      • .630 to .709
      • .787 to .886
      • .906 to .984
      • 1.100
      • 1.240 to 1.340
      • 1.400 to 1.770
      • 1.970
      • 2.200 to 2.360
      • 2.480 to 2.800
      • 3.150 to 3.540
      • 3.940 to 4.410
      • 4.920
      • 5.510 to 7.090
      • 7.870
      • 8.860 to 9.840
    • AI Springs >
      • AI .187 to .950
      • AI 1.000 to 1.750
      • AI 2.000 to 2.500
    • SP Belleville Springs >
      • SP .197 to .945
      • SP 1.142 to 3.031
    • CONTACT Disc Springs >
      • CONTACT Narrow
      • CONTACT Regular
      • CONTACT Wide
    • K Disc Springs >
      • Metric for K
      • Inch for K
    • FL Disc Springs >
      • Metric for FL
      • Inch for FL
  • Special Springs
  • Spring Design
    • Tolerances >
      • for Thickness
      • Overall Height
      • Hardness Range
      • OD + ID Guide Clearance
      • OD + ID Tolerance
      • Load Tolerance
    • Load Calculations >
      • Nomenclature
      • Load in Lbs
      • True Radius Factor
      • Corner Radius Factor
      • True Cone Height Factor
      • Flattening at Edge Factor
      • Precise Load Computing
    • About >
      • Contact Us
      • News Releases >
        • Fan Disc Second Patent
        • JPL Selects Fan Disc
        • Fan Disc Wins Patent
    • Load and Stress Calculations
    • Dynamic Loading
    • Materials Properties
    • Tightening Torque Values
    • Typical Disc Spring Apps
  • Site Map