"Why should I consider CSiPlant? I already have a pipe stress program that I like."

Legacy pipe stress programs currently used by the vast majority of pipe stress engineers ignore several important analysis considerations that often have a significant impact on design calculations. They also lack modern user interface functionality which hinders productivity as compared to CSiPlant. These legacy programs were developed in the mid-1980s or earlier with the original developers long gone decades ago.

We know that consideration of nonlinear 2nd order P-delta effects will result in more realistic analysis results, particularly with analysis of buried and seabed pipelines, but P-delta also affects plant piping design calculations as well. How much effect will P-delta have on your individual design calculations? With CSiPlant, it only takes a couple of mouse clicks to find out. CSiPlant lets users compare side-by-side results with and without P-delta.

Just as the tightening of guitar strings changes the lateral stiffness and natural frequency, axial tension load in piping and structural frame elements increases lateral stiffness of those elements, whereas compressive loads soften lateral stiffness. Legacy pipe stress programs totally ignore these real world P-delta effects on element stiffness. P-delta also accounts for loading about the deflected position of the piping which is ignored by legacy pipe stress programs.

Another important consideration ignored by legacy pipe stress programs is the sequence or order of the applied loads. Whenever friction, gaps, or soil is modeled, the order of the applied loads can and will make a difference in design calculations. To take one example, proper analysis of a winter shutdown load case scenario should not start from ambient temperature, the shutdown should realistically start from the operational state where the piping is already in a stressed and deflected position, and then transition from there to winter shutdown temperature/pressure with removal of fluid contents load, if applicable. Legacy pipe stress programs cannot properly model that load case scenario.

It doesn't take a pipe stress or structural expert to see that pipe/structure interaction can often have a profound impact on design calculations as compared to piping-only models with rigid pipe supports and anchors. Not only consideration of support structure flexibility which is important, but also consideration of imposed displacements at pipe support locations caused by structural frame displacements. Pipe racks are often designed to accommodate lateral deflections of Height/100 or Height/200 under wind or seismic load. That means 2", 3" or more imposed displacements at some pipe support locations. Sometimes even small imposed displacements can be quite impactful for design calculations. There is also a coupled analysis effect to consider, particularly with rack structures supporting large diameter piping in which the cross sectional area of some pipes can be larger than the supporting columns.

Proper consideration of pipe/structure interaction has typically been ignored or greatly oversimplified because before CSiPlant there was not a reliable practical tool to properly consider combined pipe/structure interaction. Modeling structural frames in a legacy pipe stress program is time-consuming and very limited. A typical pipe rack structural analysis model has a LOT of assigned loads which account for weight of heavy equipment, live loads, cable tray loads, fireproofing, and other entities with significant weight and mass. Those assigned loads need to be properly accounted for if you want to have a realistic analysis of piping combined with the structure.

Those assigned loads also need to be accounted for in static acceleration load cases (static seismic loads, for example) and in all dynamic analysis load cases. CSiPlant has a unique "Mass source" option which enables users to easily convert selected gravity-direction assigned loads to be included in the mass model. The mass model affects static acceleration and dynamic analysis results.

If you assign a 200 kip gravity-direction load (using concentrated point loads or distributed load) to the structural frames or piping in your legacy pipe stress program, do those newly assigned loads change the calculated natural frequencies or static acceleration results?

For those engineers who believe that it's conservative or 'close enough' to assume a rigid and undeflected pipe support structure in pipe stress analysis models, how can you know that with any degree of certainty? Have you or any of your colleagues run comparisons between results from piping-only models vs. results from more detailed models with piping and structure together? Has your company evaluated the economic and safety consequences of one modeling approach vs. the other? How about comparisons with and without P-delta? It's our claim that before CSiPlant, comparisons like this were simply not feasible because the tools were not available. With CSiPlant working with SAP2000, pipe/structure interaction (and P-delta) is now very straightforward to consider, and this represents a noteworthy leap in pipe stress analysis technology.

You'll find it surprisingly easy and reliable to import detailed SAP2000 structural models into CSiPlant which auto-connects with the piping model. CSiPlant is based on SAP2000. Once the combined pipe/structure analysis is run, piping code checks can be performed and selected pipe support loads/reactions can be automatically exported back into the SAP2000 structural model. Think about all the time, confusion and errors involved with having to work with marked-up isometrics, spreadsheets and other manual methods which attempt to communicate pipe support loads from piping stress to the structural team. The structural team then needs to spend time deciphering that data and then manually type those piping loads into their structural analysis model, one support at a time.

There are other important analysis considerations that CSiPlant offers such as nonlinear load sequencing which combines loads incrementally (important when friction or soil is modeled) including load sequencing of multiple thermal loads, nonlinear time history dynamic analysis which can account for gaps, friction, and one-way supports in the dynamic analysis, a unique nonlinear damper element, unique soil modeling features including soil distributed imposed displacements, and the time saving ability to work with user defined libraries of pipe supports and expansion joints which can be reused to name a few other CSiPlant advantages.