CAESAR II – Piping Input Screen and Propagated Values

CAESAR II – Piping Input Screen is utilized in order to edit, create, or delete model geometry.  This piping input screen has several fields that can be overwhelming to new users, and has some features that seasoned users may be under utilizing. Today I would like to talk about this dialog in detail, and provide some insight into effectively mastering this dialog to speed up and qualify your pipe stress analysis. The Piping Input Screen is pictured below:

Lets start by talking about how analysis information is stored in CAESAR II.  All the material properties of the pipe and criteria for analysis is not located on each element, but at each node. Forces, moments, and displacements can only occur at nodes.  Additionally, all mass of the piping system is included at the nodes.  These points are important to consider when you are dealing with models that have very long lengths between elbows or supports.  By not distributing nodes throughout the model on these long lengths, the analytical  model will not have the proper fidelity to displace the piping due force and strain based loads.

Taking in the fact that nodes contain and we supply all the information for analysis through them, let’s describe the most basic feature of the Classic Piping Input screen: Value Propagation.  Simply stated, this allows us to enter in a value on the first node, and then apply that same value to every node after it, unless it is changed.  If the value is changed at some node in the model down the line, then that new value will propagate to every node after it, and so on.  This feature is ubiquitous throughout this dialog, and in fact the only components on the dialog this does not apply to are listed in here.

Typically this function is straightforward when you are starting fresh with a new model.  However, this can become troublesome when dealing with a “piping component file,” (PCF) converted model, or a model that has been generated with node numbers out of sequence.  CAESAR II will still apply value propagation to the classic piping input field to a fault, and even if two pipes aren’t necessarily connected sequentially in the graphical view, the nodes are still sequential in the element list.  You can access the element list by default from the lower left hand side of the screen. List Button > Elements.

 

Reviewing this Element list can help us understand where we have altered the propagated value that CAESAR has applied to each object.  Propagated Values will always show up as RED in the element list, giving us a clear idea of where changes in properties are happening in the model.  To remove a propagated value, simply delete the red value.