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Download a PDF version of the chart here.

The above torque table was developed and simplified for marine applications, and is based on material strength.

Torque Table Equations

First, the units:

𝑇𝑃𝐼

Threads Per Inch

π‘‘π‘›π‘œπ‘š

Nominal diameter

𝐴𝑑

Tensile Stress Area

𝐹𝑦

Yield Strength

𝐹𝑖

Preload

𝑆𝑝

Proof Strength

𝐾

Coefficient of friction (=0.15 for lubricated screws)

 

To determine Preload:

𝐹𝑖=0.75𝐹𝑝

for non permanent connections1.

𝐹𝑝=𝐴𝑑𝑆𝑝
𝑆𝑝=0.85𝐹𝑦

for proof strength

To calculate bolt torque:

𝑇=𝐾𝐹𝑖𝑑

Which can also be written as:

𝑇=(0.15)(0.75)𝐴𝑑(0.85)πΉπ‘¦π‘‘π‘›π‘œπ‘š

References

  1. Β Shigley’s Machine Design, 1998.Β  p. 427 (Eq. 8-30)
  2. Β Shigley’s Machine Design, 1998.Β  p. 423 (Eq. 8-27)

Below are a links toΒ websites and calculators thatΒ our engineers have found useful.

Machine Design

Fits and Limits

Calculation of shaft and hub fits according to ISO 286 (2010)

Winch Drum Capacity Estimator

Ingersoll Rand calculator to estimate the amount of wire that can be stored on a drum.Β  Accounts for drum surface condition (grooved or smooth)