Enter the box section modulus and the pin section modulus into the calculator to determine the bending strength ratio.

Bending Strength Ratio Calculator

From Section Modulus
From OD / ID
Target BSR Designer

Enter any 2 values to calculate the third. Optionally enter an OD (e.g., tool joint/BHA OD) to show a guideline range (rule of thumb).

Calculated Box Z
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Calculated Pin Z
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Calculated BSR
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Guideline Range
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Bending Strength Ratio Formula

The following equation is used to calculate the Bending Strength Ratio.

BSR = BSM / PSM
  • Where BSR is the bending strength ratio
  • BSM is the box section modulus
  • PSM is the pin section modulus

To calculate the bending strength ratio, simply divide the box section modulus by the pin section modulus.

What is a Bending Strength Ratio?

Definition:

A bending strength ratio is a term most often used in the oil and gas industry to indicate the ratio of the box section modulus to the pin section modulus of a given connection.

How to Calculate Bending Strength Ratio?

Example Problem:

The following example outlines the steps and information needed to calculate Bending Strength Ratio.

First, determine the box section modulus. In this example, the box section modulus is 500 in³.

Next, determine the pin section modulus. The section modulus at the pin is measured to be 400 in³.

Finally, calculate the bending strength ratio using the formula above:

BSR = BSM / PSM

BSR = 500/400

BSR = 1.25