Tensile Stress in Boiler Butt Weld given Thickness of Boiler Shell Calculator

Tensile Stress Formula:

\[ \sigma_b = \frac{P_i \times D_i}{2 \times t} \]

Tensile Stress (Pa):

1. What is Tensile Stress in Boiler Butt Weld?

Definition: This is the stress developed in the boiler shell due to service loads, specifically in the butt weld joints.

Purpose: It helps engineers ensure the boiler can withstand internal pressures without failing at the welded joints.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \sigma_b = \frac{P_i \times D_i}{2 \times t} \]

Where:

\( \sigma_b \) — Tensile stress in boiler butt weld (Pa)
\( P_i \) — Internal pressure in boiler (Pa)
\( D_i \) — Inner diameter of boiler (m)
\( t \) — Thickness of boiler wall (m)

Explanation: The formula calculates the circumferential stress in a thin-walled cylindrical pressure vessel.

3. Importance of Tensile Stress Calculation

Details: Proper stress calculation ensures boiler safety, prevents catastrophic failures, and helps in compliance with pressure vessel codes.

4. Using the Calculator

Tips: Enter the internal pressure in Pascals, inner diameter in meters, and wall thickness in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical safety factor for boiler design?
A: Safety factors typically range from 3.5 to 4.5 depending on the design code and application.

Q2: Why is the thickness in the denominator?
A: Thinner walls result in higher stress for the same pressure, hence the inverse relationship.

Q3: Does this formula account for longitudinal stress?
A: No, this calculates circumferential (hoop) stress only. Longitudinal stress would be half this value.

Q4: What's the ±5% tolerance for?
A: It accounts for measurement uncertainties and material property variations.

Q5: When would this formula not be accurate?
A: For very thick-walled vessels (where t > Di/20) or under extreme temperatures.