Internal Forces in Pipe Elements

Related Topics

Forces corresponding with the coordinate axes direction are positive. Counter-clockwise moments (looking from the end of the axis on which the moment acts) are positive.

Forces can be displayed in the following ways (fig. 2):

A - automatically added nodes (invisible), B - dummy node, visible in 3D view

Fig. 2

Two force lines are always displayed for elements. Forces are not displayed for bends, since they are equal to force in adjoining pipe cross-sections.

Elements are ordered in the FORCES table in the order they were entered in input data.

Table view and contents depend on several properties, which must be input:



Operating Mode

Choose operation mode for which the results will be displayed

Maximum - the maximum value will be displayed in every cell from all operation modes

Here you can see analysis results from each of additional force-based loading, seismic, wind, and ice loading


For every operating mode software calculates several submodes (piping states)

  • Maximum - maximum force value (for the absolute value) from all design states

  • Operation state (only weight) - only weight and pressure without taking into account thermal expansion, support displacement and stretch (1st  stage)

  • Operation state (all loads): weight, pressure, thermal expansion, support displacement, stretch (2nd  stage)

  • Operation state (regular loads): used only for SNIP 2.05.06-85 and SP 36.13330.2012.

  • Cold mode (taking into account relaxation for high-temperature pipelines)

  • Test state

For more information, see force and effect combination.

Occasional Loads

  • Maximim + Seismic. Seismic load cases are considered

  • Maximum and minimum + Seismic

Show Effective Axial Force

If internal forces table is used for nozzle or valve loads calculation, then thrust force P*Ac should be subtracted from axial load, where P - internal pressure, Ac=pi*(D-2t)^2/4 - cap area, D - outer nozzle diameter, t - nozzle wall thickness. Learn more about effective axial force.

Coordinate system selection

Forces and moments are displayed for the following coordinate axes:

Fig. 1. Internal forces in pipe element

Menu Access

After analysis: Output > Internal Forces & Moments