Hello,

I was wondering what was the best way to represent a piping line that connects to an equipment and continues afterwards.

I have a clean steam unit that filters steam for sanitary application. This unit is a floor mounted skid on support structure. My hypothesis is that it acts as a rigid with anchored connexions to my piping lines.

Here is an overall view of what I'm trying to represent :
[img:left]https://imgur.com/gi2W86t[/img]

I chose to represent this with a weightless rigid between both flanged connexions with anchors at both connecting nodes :
[img:left]https://imgur.com/XodVEVD[/img]

Would that be a good approach ?

Thanks for the help

Typically for equipment you're connected to, especially in hot applications like steam, you'd model the equipment using rigids.

This is done by starting at the anchor/support location of the equipment and then you work up to the piping and apply Cnodes. This method captures the growth of the equipment's nozzles.

If your skid has calculated displacements, you could just use those instead and not model any rigids connecting the piping.

If I understand correctly, you suggest modelling rigid elements from the anchors/baseplates of the equipement, up to the actual piping connections ?

You also mentioned applying CNodes. You would use CNodes between what elements exactly ? Each end of interconnected rigids would be connected to a similar CNode ?

Philosophically, you want CAESAR to calculate the displacements that will match real life, and can vary from equipment to equipment.

How you achieve that is a personal decision, and can be subject to debate.

In general, square boxes and flat plates are anything but rigid, and you have to make the decision if the box moves the pipe or if the pipe moves the box. Modeling the box as a rigid is somewhere in the middle, which leans towards the box moving the pipe, but will allows pipe loads to be transmitted through the box to the other pipe.

As anubis indicates, the equipment is mounted, and if heated, the equipment attachment locations will move upwards from the ground.

In an ideal world, you would be able to get a rough estimate of the piping loads, run the equipment connections through FEA and estimate stiffnesses for your equipment connections (rather than the 1e12 lb/in anchors in CAESAR), and cycle until you get reasonable agreement between the two.

Philosophically, you want CAESAR to calculate the displacements that will match real life, and can vary from equipment to equipment.

How you achieve that is a personal decision, and can be subject to debate.

In general, square boxes and flat plates are anything but rigid, and you have to make the decision if the box moves the pipe or if the pipe moves the box. Modeling the box as a rigid is somewhere in the middle, which leans towards the box moving the pipe, but will allows pipe loads to be transmitted through the box to the other pipe.

As anubis indicates, the equipment is mounted, and if heated, the equipment attachment locations will move upwards from the ground.

In an ideal world, you would be able to get a rough estimate of the piping loads, run the equipment connections through FEA and estimate stiffnesses for your equipment connections (rather than the 1e12 lb/in anchors in CAESAR), and cycle until you get reasonable agreement between the two.