This topic presents different approaches to constructing triunions and the resulting differences in the obtained results. The pipe route and all process parameters are identical in each model.
In the first variant, the RS support, LG is used under the arch at the starting point of the arch, as shown in the figure below. The support acts along the center line of the vertical run and does not limit the rotation of the arch.
Below are the stress results.
Below are the results of the forces on the supports.
In the second variant, the identical RS support, LG, is used under the arch, but at the center point of the arch, as shown in the drawing below. You can't throw LG into the center of the arch because it gives a slightly funny graphic effect.
Therefore, in the second variant, the identical RS support was used under the arch. The LG function was moved to the beginning of the arch. Stress results:
Results of forces at supports.
In the third variant, the pipe arc is to be supported by a triunion placed directly under the pipe. Let's assume that the triunion DN 200/8' is 500 mm long. The beam element is used to model the fictitious leg. The beginning of the triunion is to be placed at the midpoint of the arc. The triunion pipe is the structure element. Unfortunately, for this reason, a regular support cannot be placed on the structure element. Only a fixed point is possible. Regular supports can be simulated on it, but without gaps. The stress results are below.
In the fourth variant, the pipe bend is to be supported by a triunion placed directly under the pipe. A short rigid beam element is used to connect the pipe segment to the bend to model a fictitious triunion pipe. The actual length of the triunion is 500 mm. The triunion pipe is a piping element, which means that any support can already be assumed. Stress results:
Forces at the support.
SUMMARY
Each variant gave different results. The load combination that gives the greatest stress is always the same.
