1. What is Pipe Pressure Calculation (Barlow's Formula)?

Definition: This calculator determines the internal pressure a pipe can withstand based on material stress, wall thickness, and diameter.

Purpose: It helps engineers and technicians verify pipe strength for various pressure applications in oil/gas, plumbing, and industrial systems.

2. How Does the Calculator Work?

The calculator uses Barlow's formula:

Where:

• \( P \) — Internal pressure (psi)
• \( S \) — Hoop stress (psi)
• \( t \) — Wall thickness (inches)
• \( D \) — Outside diameter (inches)

Explanation: The formula calculates the pressure at which the pipe's hoop stress equals the material's yield strength.

3. Importance of Pipe Pressure Calculation

Details: Proper pressure calculation ensures pipe safety, prevents failures, and helps select appropriate materials for specific pressure requirements.

4. Using the Calculator

Tips: Enter the material stress (typically 60-80% of yield strength), wall thickness, and outside diameter. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What safety factor should I use?
A: Typically 0.72 for pipelines (B31.4/B31.8), but varies by application. Always check relevant codes.

Q2: Does this work for all pipe materials?
A: Yes, but the stress value (S) must be appropriate for the specific material and temperature.

Q3: Should I use inside or outside diameter?
A: Barlow's formula uses outside diameter (D). For thin-walled pipes, the difference is negligible.

Q4: What's the difference between hoop stress and longitudinal stress?
A: Hoop stress (used here) is circumferential stress from internal pressure, typically twice the longitudinal stress.

Q5: How accurate is Barlow's formula?
A: Very accurate for thin-walled pipes (D/t > 10). For thick-walled pipes, use Lamé equations instead.