This post reminds me of one of my very first piping flexibility analysis jobs where the calculated stresses were on the order of 1E6 psi on a system I was troubleshooting. I knew this stress level was impossible so I dug into the background of the program (a mainframe program preceeding CAESAR) to understand how the calculations were made.

This action was a revelation to me. I learned 2 things: 1) piping programs like CAESAR II assume infinite elasticity (as was mentioned in a previous post), and 2) always look at the results to understand whether the model is behaving right (i.e. have any physical laws been violated, do calculated displacements match actual movements in the field, are restraint loads inactive [liftoff] or exceedingly high and do they match reality, can I duplicate program results with some simple manual calculation methods within acceptable accuracy, etc.).

As I work with young engineers I have found a tendency for them to unquestioningly accept computer calculated results (...it must be right, that's what the computer calculated...) without trying to understand whether their model matches reality. One really needs to watch out for the GIGO trap. (GIGO = Garbage In, Garbage Out)

By the way, members of API get a 50% discount on any API publications. This brings API-579 to about $300, close to the price of the volumes of the ASME piping codes.