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High-temperature systems require precise calculations to ensure pipe integrity and safety. Properly determining pipe thickness and wall stress helps prevent failures and extends equipment lifespan. This article provides example calculations for these critical parameters.
Calculating Pipe Thickness
The minimum required pipe thickness can be calculated using the formula:
t = (P × D) / (2 × S × E) + corrosion allowance
Where:
- P = Internal pressure
- D = Outside diameter of the pipe
- S = Allowable stress of the pipe material
- E = Quality factor (usually 1 for seamless pipes)
For example, with an internal pressure of 10 MPa, pipe diameter of 100 mm, allowable stress of 150 MPa, and E = 1, the minimum thickness is:
t = (10 × 100) / (2 × 150 × 1) = 3.33 mm
Calculating Wall Stress
The hoop stress in a pipe under internal pressure is given by:
σ = (P × D) / (2 × t)
Using the previous example with a pipe thickness of 3.33 mm, the hoop stress at 10 MPa pressure and 100 mm diameter is:
σ = (10 × 100) / (2 × 3.33) ≈ 150 MPa
Additional Considerations
High-temperature conditions can affect material properties, requiring adjustments in allowable stress values. Corrosion allowances should also be added to account for material degradation over time. Regular inspections and safety margins are essential for reliable operation.