Input variables

Generic variables

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

Design Pressure – Pd
Pressure assumed to be present in the component according to the design terms
Design Temperature – Td
Temperature assumed to be present in the component according to the design terms
Name of selected material used for the construction of the component

Specific variables

These variables are component specific

Outside Diameter – De
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 – dn
Thickness ‘as is’, meaning it is the design thickness taking into account corrosion and tolerance.
Corrosion – Ca
Amount of thickness that accounts for the possible effects of corrosions.
Tolerance – tol
Tolerance in thickness for production
Strength reduction coefficient – z
Effectiveness of the strength, depending on whether joints are seamless, welded, or expected to perform worse than the base material properties
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.
Out of roundness – u
relative out of roundness regarding the shape of the shell.
Margin – γ

Calculated Values

Allowable Stress at Temperature – f
Stress in the component at which it is still allowed (without failure) to use the component
Modulus of elasticity – E
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.
Unsupported length – L
Actual length of the straight part of the pipe that is unsupported.
Number of lobs – n
Positive integer ≥ 2, to be determined such that the required thickness becomes maximum.
Nominal Required Thickness – drn
Based on the input, this is the calculated thickness that is required to sustain the loads. The nominal value should be smaller than the nominal design thickness.

Scope errors

Design temperature material is out of scope.
The material properties are not available at the design temperature.
Wall thickness is out of scope: required d ≤ 0.2 De
This code determines for pipes a maximum thickness.


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.
Insufficient wall thickness
Wall thickness is insufficient to bear the applied loads. Increase the wall thickness.


Restricted unsupported length: L = x mm
The unsupported length is restricted to a maximum: LL′

Calculation errors

Can't calculate maximum unsupported length for external pressure.
The shell has insufficient strength to determine the unsupported length.