 |
Barlow's Formula is Used to Determine: |
| |
• Internal Pressure at Minimum Yield
• Ultimate Bursting Pressure
• Maximum Allowable Operating Pressure
• Mill Hydrostatic Test Pressure |
| |
The Formula is Expressed as P=2St/D, Where: |
| |
|
P = pressure, psig
t = nominal wall thickness, in inches (i.e. .375)
D = outside Diameter in inches
S = allowable stress in psi, which depends on the pressure being determined utilizing Yield or Tensile depending on what is trying to be determined |
| |
For Example: |
| |
|
Internal Pressure at Minimum Yield:
S= SMYS - minimum yield for grade of pipe |
| |
Ultimate Bursting Pressure: |
| |
|
S = SMTS - minimum tensile strength for grade of pipe |
| |
Maximum Allowable Operating Pressure: |
| |
|
S = SMYS - reduced by a design factor |
| |
Mill Hydrostatic Test Pressure: |
| |
|
S = SMYS - reduced by a design factor depending on OD and grade |