Butt Weld Section Modulus Equation and Calculation

Metric Thread ISO Minimum Thread Engagement Calculator

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Engineering Metals and Materials | Strength of Materials

For equations and illustrative graphics see:
Minimum Thread Engagement Formula and Calculation ISO

The screw should fail before the thread strips. For this, it is necessary the shear area of the threaded feature be at least 2 times the tensile area. (Assuming the threaded feature is of the identical material).

All units shall be consistant and given in inches.

Minimum ISO Thread Engagement Calculation
Variables
Tensile Stress Area 100 ksi or less (At) = Tensile Stress Area 100 ksi or more (At) =
Major Diameter (D) =
Threads per inch TPI (p = 1/TPI)) =
Results
Minimum Thread Engagement Length (Le) =