Diameter of bolt pitch circle given torque resisted by n bolts Calculator

Bolt Pitch Circle Diameter Formula:

\[ d_{pitch} = \frac{8 \times T_{bolt}}{f_s \times \pi \times d_{bolt}^2 \times n} \]

Torque resisted by bolt:

N·m

Shear Stress in Bolt:

Diameter of Bolt:

Number of Bolts:

Tolerance:

Bolt Pitch Circle Diameter (m):

1. What is Bolt Pitch Circle Diameter?

Definition: The diameter of the circle that passes through the center of all bolts in a bolted joint.

Purpose: It's a critical dimension in mechanical design that determines the spacing of bolts in circular patterns.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ d_{pitch} = \frac{8 \times T_{bolt}}{f_s \times \pi \times d_{bolt}^2 \times n} \]

Where:

\( d_{pitch} \) — Diameter of bolt pitch circle (meters)
\( T_{bolt} \) — Torque resisted by bolt (Newton-meters)
\( f_s \) — Shear stress in bolt (Pascals)
\( d_{bolt} \) — Diameter of bolt (meters)
\( n \) — Number of bolts

Explanation: The formula calculates the required pitch circle diameter based on the torque capacity of the bolted joint.

3. Importance of Pitch Circle Diameter

Details: Proper pitch circle diameter ensures even load distribution among bolts, prevents joint failure, and maintains structural integrity.

4. Using the Calculator

Tips: Enter the torque, shear stress, bolt diameter, number of bolts, and tolerance percentage (default ±5%). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical tolerance for pitch circle diameter?
A: ±5% is common, but this depends on application requirements and manufacturing capabilities.

Q2: How does bolt diameter affect the calculation?
A: Larger bolt diameters (squared in the formula) significantly reduce the required pitch circle diameter for the same torque.

Q3: When would I need more bolts in the pattern?
A: More bolts are needed when either the torque increases or when you want to reduce the pitch circle diameter.

Q4: What's a typical shear stress value for bolts?
A: This varies by material, but common steel bolts might have allowable shear stress of 140-210 MPa (140,000,000-210,000,000 Pa).

Q5: How does this relate to flange design?
A: This calculation is fundamental for designing circular flange connections in piping and pressure vessels.