Total Axial Stress in Vessel Shell Calculator

Total Axial Stress Formula:

\[ \sigma_{total} = \frac{p \cdot D_i}{4 \cdot t \cdot J} + \frac{p_j \cdot d_i}{2 \cdot t \cdot J} + \frac{2 \cdot \Delta p \cdot d_o^2}{3 \cdot t^2} \]

Internal Pressure in Vessel:

N/mm²

Internal Diameter of Shell:

Shell Thickness:

Joint Efficiency for Shell:

(0-1)

Design Jacket Pressure:

N/mm²

Internal Diameter of Half Coil:

Max Coil-Shell Pressure Difference:

N/mm²

Outer Diameter of Half Coil:

Total Axial Stress: N/mm²

1. What is Total Axial Stress in Vessel Shell?

Definition: Total axial stress in a vessel shell is the combined stress acting along the longitudinal axis of the vessel, resulting from internal pressure, jacket pressure, and pressure differences between coils and shell.

Purpose: This calculation is crucial for ensuring the structural integrity of pressure vessels, particularly those with half-coil jackets, under various operating conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \sigma_{total} = \frac{p \cdot D_i}{4 \cdot t \cdot J} + \frac{p_j \cdot d_i}{2 \cdot t \cdot J} + \frac{2 \cdot \Delta p \cdot d_o^2}{3 \cdot t^2} \]

Where:

\( \sigma_{total} \) — Total axial stress (N/mm²)
\( p \) — Internal pressure in vessel (N/mm²)
\( D_i \) — Internal diameter of shell (mm)
\( t \) — Shell thickness (mm)
\( J \) — Joint efficiency for shell (0-1)
\( p_j \) — Design jacket pressure (N/mm²)
\( d_i \) — Internal diameter of half coil (mm)
\( \Delta p \) — Maximum difference between coil and shell pressure (N/mm²)
\( d_o \) — Outer diameter of half coil (mm)

3. Importance of Total Axial Stress Calculation

Details: Proper calculation of total axial stress ensures vessel safety, prevents structural failure, and helps in compliance with pressure vessel design codes like ASME BPVC.

4. Using the Calculator

Tips: Enter all required parameters in the appropriate units. The calculator accounts for ±5% variation in input values. Joint efficiency typically ranges from 0.7 for welded joints to 1.0 for seamless construction.

5. Frequently Asked Questions (FAQ)

Q1: What is joint efficiency?
A: Joint efficiency is a factor that accounts for the strength reduction at welded joints compared to the base material, typically ranging from 0.7 to 1.0.

Q2: Why consider pressure difference between coil and shell?
A: The pressure difference creates additional stresses that must be accounted for in the design to prevent failure.

Q3: What's a typical shell thickness range?
A: Shell thickness typically ranges from 5mm for small vessels to 50mm or more for large, high-pressure vessels.

Q4: How accurate is the ±5% margin?
A: The 5% margin accounts for typical variations in material properties, manufacturing tolerances, and measurement uncertainties.

Q5: What safety factor should I apply to the result?
A: The required safety factor depends on the design code being followed, but typically ranges from 3 to 4 for pressure vessels.