🔧 Pipe Burst Pressure Calculator
Calculate pipe burst pressure, internal yield pressure, and maximum allowable working pressure using Barlow's formula. Enter pipe dimensions and material strength to instantly determine pressure ratings with safety factors and design coefficients.
What Is Pipe Burst Pressure?
Pipe burst pressure is the internal pressure at which a pipe will rupture or fail. It is a critical parameter in pipeline design, pressure vessel engineering, and industrial safety. The most widely used formula for estimating burst pressure is Barlow's formula, which relates internal pressure to the pipe's dimensions and material strength:
P = (2 × S × t) / D
where P = pressure, S = material strength (yield or ultimate tensile), t = wall thickness, D = outside diameter
Barlow's formula provides three important pressure values depending on which material strength is used:
- Internal Yield Pressure (Py): Uses yield strength (Sy) — the pressure at which permanent deformation begins.
- Ultimate Burst Pressure (Pt): Uses ultimate tensile strength (St) — the theoretical pressure at which the pipe ruptures.
- Maximum Allowable Working Pressure (Pa): Uses yield strength with design factors and joint efficiency — the safe operating pressure for service.
How to Use This Calculator
This calculator solves Barlow's formula for all three pressure values:
- Outside Diameter (OD): The pipe's external diameter.
- Wall Thickness (t): The pipe's wall thickness (minimum, not nominal, for conservative design).
- Material Strength (S): Either yield strength or ultimate tensile strength of the pipe material.
- Safety Factor (SF): A design multiplier. Use 1.0 for burst pressure, 1.5–6 for working pressure.
- Design Factor (Fd): Code-based factor for pipeline class (0.72 for liquid, 0.40–0.72 for gas).
- Joint Efficiency (E): Accounts for the pipe's longitudinal seam (1.0 for seamless, 0.85 for ERW, 0.6 for furnace butt weld).
For example, a 4" Schedule 40 pipe (OD = 4.500 in, t = 0.237 in) made of A53 Gr. B steel (Sy = 35,000 psi, St = 60,000 psi):
Py = 2 × 35,000 × 0.237 / 4.500 = 3,687 psi
Pt = 2 × 60,000 × 0.237 / 4.500 = 6,320 psi
Pa = 2 × 35,000 × 0.72 × 1.0 × 0.237 / 4.500 = 2,654 psi
Why Use This Calculator?
- Three pressure values: Get internal yield, ultimate burst, and maximum allowable working pressure in one calculation.
- Unit flexibility: Enter dimensions in inches or mm, and strength in psi or MPa.
- Design factors included: Apply safety factors, design factors, and joint efficiency factors per code.
- Step-by-step breakdown: See exactly how each pressure value is calculated.
- Free & private: No registration, no data storage — all calculations are done in your browser.
❓ Pipe Burst Pressure Calculator FAQ
What is Barlow's formula?
Barlow's formula is P = 2 × S × t / D, where P is pressure, S is material strength, t is wall thickness, and D is outside diameter. It is used to estimate the internal pressure at which a pipe will yield or burst.
What is the difference between yield pressure and burst pressure?
Yield pressure uses the material's yield strength and represents the pressure at which permanent deformation begins. Burst pressure uses the ultimate tensile strength and represents the theoretical pressure at which the pipe ruptures.
What safety factor should I use?
Use 1.0 for theoretical burst pressure calculations. For working pressure, typical safety factors are 1.5 to 6, depending on the application and governing code. ASME B31.3 uses design factors of 0.72 for liquid pipelines and 0.40–0.72 for gas pipelines.
What is joint efficiency (E)?
Joint efficiency accounts for the strength reduction caused by the pipe's longitudinal seam. Seamless pipe has E = 1.0, ERW pipe has E = 0.85, and furnace butt-welded pipe has E = 0.60.
What is the D/t ratio and why does it matter?
The D/t ratio (outside diameter divided by wall thickness) determines whether a pipe is considered thin-wall or thick-wall. Barlow's formula is most accurate for thin-wall pipes (D/t > 20). For thick-wall pipes, the Lamé equation is more accurate.
What is the ultimate tensile strength of common pipe materials?
Common values: A53 Gr. B = 60,000 psi, A106 Gr. B = 60,000 psi, A53 Gr. A = 45,000 psi, API 5L X52 = 66,000 psi, A312 TP316 (stainless) = 75,000 psi.
What is the maximum allowable working pressure (MAWP)?
MAWP is the maximum pressure at which a pipe can safely operate. It is calculated by applying design factors and joint efficiency to the yield strength: Pa = 2 × Sy × Fd × E × t / D.
How accurate is Barlow's formula?
Barlow's formula is a thin-wall approximation. It is generally accurate for D/t > 20 and provides conservative results for most engineering applications. For critical applications, verify with the Lamé equation or finite element analysis.
Is this calculator free?
Yes, this calculator is completely free to use. No registration or personal data storage is required.
What pipe schedules are available?
Common pipe schedules include Schedule 40 (standard wall), Schedule 80 (extra strong), and Schedule 160 (double extra strong). For a 4" pipe: Schedule 40 has t = 0.237 in, Schedule 80 has t = 0.337 in.