Input variables
Generic variables
These variables can be found in virtually all reports as input variables
- Design Pressure – Pc
- Pressure assumed to be present in the component according to the design terms
- Design Temperature – T
- Temperature assumed to be present in the component according to the design terms
- Material
- Name of selected material used for the construction of the component
Specific variables
These variables are component specific
- Outside Diameter – Do
- Outside diameter of the attached part. The diameter runs from the outside of the wall to the opposite outside of the wall, through the center of the circle.
- Nominal Thickness – en
- Thickness ‘as is’, meaning it is the design thickness taking into account corrosion and tolerance.
- Corrosion – c0
- Amount of thickness that accounts for the possible effects of corrosions.
- Tolerance – c1
- Tolerance in thickness for production
- Infinite length – L′
- The unsupported lenght of the shell is infitely long, meaning the external pressure can not collapse the shell.
- Maximum unsupported length – L
- Maximum length of the straight part of the pipe that is unsupported.
Pipe
Calculated Values
- Allowable stress at operating temperature – S
- Stress in the component at which it is still allowed (without failure) to use the component.
- Yield strength at operating temperature – Rpt
- Stress in the component at which the component starts to plastically deform at operating temperature.
- Modulus of elasticity – Et
- Tendency to deform (tensile strain) along an axis when opposing forces (tensile stress) are applied along that axis.
- Poisson's ratio – ν
- (Negative) ratio of transverse to axial strain. An extension (or contraction) in the direction of a load corresponds in a contraction (or extension) in a direction perpendicular to the applied load. The ratio between these two quantities is the Poisson's ratio.
- Number of circumferential waves – ncyl
- Number of circumferential waves for an unstiffened part of cylinder. The value is an integer ≥ 2 to minimize the value of Pm
- Critical strain – ε
- Mean elastic strain at collapse
- Yield pressure – Py
- Pressure at which mean circumferential stress in cylindrical shell midway between stiffeners reaches yield point of material.
- Critical pressure – Pm
- Theoretical elastic instability pressure for collapse of perfect cylindrical shell
- Critical pressure – Pr
- Lower bound collapse pressure
- Maximum Allowable Pressure – Pa
- The maximum pressure at which the component can be used in operation. This value should be larger than the design pressure.
Errors
- Can’t find material ‘MaterialName’ in database
- Material could not be found in database. Select an existing material name, or select another material via the material selection window.
Remarks
- Restricted unsupported length: L = x mm
- The unsupported length is restricted to a maximum: L ≤ L′
Calculation errors
- Can't calculate maximum unsupported length for external pressure.
- The shell has insufficient strength to determine the unsupported length.