As I have follow other posts I am always interested to see comments about linear/non linear pipe supporting systems.

The piping systems we design are always non-linea. Can someone satisfy my curiosity about when they use linear analysis and why?

We should not be doing linear analysis - it's that simple.

Then why some people do it? There was a time when non linearity could not be handled by pipe stress programmes yet there was no catastrophy in using linear analysis which was the only option. It is just the fact that due to technological advances we have an option ( non linear analysis)which is more technically accurate , so why to use the other option?

Linear analyis is mostly used for Dynamic analysis where the non linear analysis is not simple ,takes up much more computational time and resources and is usually not available in commercial pipe stress programmes.

Regards