There is a library supplied with NX , it is more like an example library than a real but, it does contain some pipes,
you also have the option to specify "Circular / Rectangular/ flat oval" or "Space reservation" and enter any value .
when you have the routing application running, open the Reuse library tab and you will see the available pipes and fittings.
( Not visible in any other applications)
Notice that whoever designed the architecture of the NX routing had a way of thinking that is quite different to most people...,
so if you don't see the type of pipe etc you are looking for in the library,
go Preferences- routing - Disciplines - .... and the content of the Reuse library will change.
Also , Routing is separated by licensing between Routing electrical and mechanical, the libraries are different, the fundamental functionality is the same ( Path -stock etc) but there are add-on functionality which is different.
Regards,
Tomas
