Pipe Schedule Calculator — Formula
## Pipe Wall Thickness Design
The required pipe wall thickness depends on the internal pressure, pipe diameter, material allowable stress, and safety factors. The Barlow formula provides the starting point.
### Barlow Formula
**t = P × D / (2 × S × E)**
The ASME B31.3 modified version: **t = P × D / (2 × (S × E + P)) + CA**
where P is pressure, D is outside diameter, S is allowable stress, E is weld joint efficiency, and CA is corrosion allowance.
The required pipe wall thickness depends on the internal pressure, pipe diameter, material allowable stress, and safety factors. The Barlow formula provides the starting point.
### Barlow Formula
**t = P × D / (2 × S × E)**
The ASME B31.3 modified version: **t = P × D / (2 × (S × E + P)) + CA**
where P is pressure, D is outside diameter, S is allowable stress, E is weld joint efficiency, and CA is corrosion allowance.
Exemplo Resolvido
A 6" Sch pipe (OD=168.3 mm) at 10 MPa, S=137.9 MPa, E=1.0, CA=1.5 mm.
- Barlow: t = 10 × 168.3 / (2 × 137.9 × 1.0) = 1683 / 275.8 = 6.10 mm
- ASME modified: t = 10 × 168.3 / (2 × (137.9 + 10)) + 1.5
- t = 1683 / 295.8 + 1.5 = 5.69 + 1.5 = 7.19 mm