Wall Thickness Calc

Pipe wall thickness calc according to

Calculation Reference
Subsea Piping

Offshore Pipes

API RP 1111

API RP 1111 (Recommended Practice for Design, Construction, Operation, and Maintenance of Offshore Hydrocarbon Pipelines) provides guidelines for the design and construction of offshore pipelines, including pipe wall thickness calculation.

Here's a simplified procedure to calculate the pipe wall thickness according to API RP 1111:

1. Determine the design parameters, such as:

   • Design pressure (P_d)
   • Design temperature (T_d)
   • Pipeline material and its properties (yield strength, SMYS, and tensile strength)
   • Corrosion allowance
   • Mill tolerance (pipe manufacturing tolerance)
   • Safety factors

2. Calculate the hoop stress in the pipe wall due to the internal pressure using Barlow's formula:

σ_h = (2 * P_d * D_o) / (2 * t)

Where: σ_h = Hoop stress (MPa, psi) P_d = Design pressure (MPa, psi) D_o = Outside diameter of the pipe (mm, inches) t = Pipe wall thickness (mm, inches)

3. Determine the required pipe wall thickness based on the design parameters and API RP 1111 guidelines:

t_required = (D_o * P_d) / (2 * (SMYS / S_F) - P_d)

Where: t_required = Required pipe wall thickness (mm, inches) D_o = Outside diameter of the pipe (mm, inches) P_d = Design pressure (MPa, psi) SMYS = Specified minimum yield strength of the pipe material (MPa, psi) S_F = Safety factor (as per API RP 1111 guidelines)

4. Add the corrosion allowance and mill tolerance to the required wall thickness:

t_final = t_required + corrosion_allowance + mill_tolerance

5. Select a commercially available pipe wall thickness that meets or exceeds the final calculated thickness.

Please note that this is a simplified procedure, and the actual calculation of pipe wall thickness according to API RP 1111 may involve additional factors, such as axial loads, buckling, and temperature effects. It's essential to consult with a qualified engineer and follow the API RP 1111 guidelines to ensure a proper and safe pipeline design.