# Internal Forces in Pipe Elements 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):

• no bends or valves  are present in nodes  M and N of element  M-N  (fig. 2.a). Forces are display for pipe cross-sections 1 and 2  adjoining nodes  M and N from the side of nodes  N and M, respectively.

• valve is present in node N of element М-N (fig. 2.b). Forces in element М-N  are displayed for pipe cross-sections 1 and 2. Cross-section 1 adjoins to node М from the side of node N, while cross-section 2 adjoins the valve from the side of node  M.

• bend is present in node N of element М-N  (fig. 2.c). Forces in element М-N are displayed for pipe cross-sections 1 and 2. Cross-section 1 adjoins to node М from the side of node N, while cross-section 2 adjoins the bend from the side of node М.

• for tees, forces in pipes adjoining the run are displayed for cross-sections 1 and 2 of node N (fig. 2.d), while in pipes adjoining the branch they are displayed for cross-section 3 of a symbolic node, placed at a distance of half the run diameter from node N. 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:

 Property Description 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 Submode 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: In global axes (X, Y, Z) - Px, Py, Pz, Mx, My, Mz (fig. 1) In local element axes (Xm, Ym, Zm) Fig. 1. Internal forces in pipe element