The model consists of steam piping laid over the pipe rack operating at temperature of 495 Deg.C from WHRSG boilers to common steam distribution header with a tapping in between to process . We have modeled the piping with expansion loops to take care of stress requirements and rod hangers, where the horizontal displacement is more than 140mm. In the restraint summary of the model, we have noticed that the +YROD at few node numbers are loaded with force in 'X' & 'Z' axis with a displacement in 'Y' (vertical) axis, in spite of increased rod length, rod tolerance & change in rod increment.

For example, the said problem is with the rod hanger(+YROD) at node 1300, where the displacement is X= -155mm, Y= -4.894mm & Z= 50.765mm. However at few node numbers we have observed that in spite of large horizontal displacement the above explained problem does not exist.

It is also not clear to us, why the vertical displacement is appearing in the displacement summary for the rod hangers(+YROD) which has the above problem and this displacement varies with the change in rod length. Please clarify.