Piping stress analysis

A little history about piping stress software

 A little history. Strictly speaking, NONE of these new software products have anything in Common with the Navy Mare Island MEC-21 (and its derivatives like MEL-40) pipe stress analysis program (except that they use Castigliano's second theorem for the basic structural solution). I began using MEC-21 in 1963 and I had the responsibility to maintain and update it for 12 years (we made the conversion from IBM 7094 dependent Fortran II to Fortran IV). MEC-21 was written by Bob Creamer based upon the chapter of “The Piping Handbook”, Fifth Edition, (S. Crocker and R. King) by John Brock (If anyone has a fifth edition, this chapter is historic and you should read it again). MEC-21 used the flexibility method in its solution engine (I still have the original manual – yes, I know, “get a life”). This (flexibility method) greatly limited what we could do with MEC-21 as far as adapting it to perform dynamic analyses was concerned. All these new products use the stiffness method.

The first "break-through" came when the SAP IV software became available in the public domain. The Sap series of structural analyses programs came out of U-Cal Berkley and they used the stiffness method and beautifully written "top-down" Fortran IV in writing the program. Due to the "clean-ness" of the SAP analytical engine, it was adapted by several proprietary software products in 1970's and 1980's. The SAP software included a TRUE curved beam element and this was something else that MEC-21 lacked (MEC-21 created many lengths of slightly angled straight pipe to approximate the bend). If you did side by side comparisons of an analysis of the same structure there would be differences. If you analyzed a close coupled piping system with a dominant largeradiusbend in ittheSAPsoftware would give you an accurate solution but MEC-21 would "go wrong". One of the dominant software products at that time, TRILFEX (by Reid McNally), was originally based upon the MEC-21 analytical engine and then they (Dan Yongue at TRIFLEX – a great guy) created another version based upon the SAP analytical engine. TRIFLEX offered both versions ("Flexibility and "Stiffness") for a while. 

Tony Paulin’s approach, when he originally wrote Caesar II, was completely different and all his code was original – an entirely new analytical engine.

https://sites.google.com/site/fumioandostockyards/stock/analysis

The Meaning of the Class 1 Nuclear Piping Equations in NB-3650

https://becht.com/blog/the-meaning-of-the-class-1-nuclear-piping-equations-in-nb-3650