# Input variables

## Generic variables

These variables can be found in virtually all reports as input variables

- Design Pressure –
`P`_{c} - 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 –
`D`_{o} - 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 –
`e`_{n} - Thickness ‘as is’, meaning it is the design thickness taking into account corrosion and tolerance.
- Corrosion –
`c`_{0} - Amount of thickness that accounts for the possible effects of corrosions.
- Tolerance –
`c`_{1} - 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 –
`R`_{pt} - Stress in the component at which the component starts to plastically deform at operating temperature.
- Modulus of elasticity –
`E`_{t} - 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 –
`n`_{cyl} - Number of circumferential waves for an unstiffened part of cylinder. The value is an integer ≥ 2 to minimize the value of
`P`_{m} - Critical strain –
`ε` - Mean elastic strain at collapse
- Yield pressure –
`P`_{y} - Pressure at which mean circumferential stress in cylindrical shell midway between stiffeners reaches yield point of material.
- Critical pressure –
`P`_{m} - Theoretical elastic instability pressure for collapse of perfect cylindrical shell
- Critical pressure –
`P`_{r} - Lower bound collapse pressure
- Maximum Allowable Pressure –
`P`_{a} - 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.