Pipe Pressure Calculation

The calculation of pipe pressure is influenced by multiple factors, including diameter, wall thickness, material quality, temperature, manufacturing process effects, dynamic and static loads, fluid type, and more. Due to all these factors, achieving an accurate pressure calculation is not easy, even theoretically.

Considering certain safety factors, this article will analyze the pressure calculation of a pipe under normal conditions, regardless of operating temperature.

Formula for Pressure Test Calculation:

P = 20 × s × k × t / D

• P: Hydrostatic test pressure (Bar)
• k: Percentage coefficient of yield strength
• s: Minimum yield strength (MPa)
• D: Outer diameter (mm)
• t: Wall thickness (mm)

Determination of k value:

For pipes manufactured according to DIN 2448, k = 0.70 can be assumed.

For API 5L, the values are as follows:

• GrA and GrB: k = 0.60
• X42 - X80:
  • k = 0.60 (Outer diameter < 5 9/16 inches)
  • k = 0.75 (6 5/8 inches < Outer diameter)
  • k = 0.85 (10 ¾ inches < Outer diameter < 18 inches)
  • k = 0.90 (Outer diameter > 20 inches)

Determination of s value:

To determine the minimum yield strength (s), the following values can be used for common grades:

• St 37: 235 MPa
• St 44: 275 MPa
• St 52: 355 MPa
• Gr B: 240 MPa