This tutorial is very good but I have to model in 3D an existing piping installation, for my grid I can create it in ref and thus have it in each room I open? If so, how to do it? Because in an assembly I have less function, I tried to insert mechanically welded components such as pipe diam 50 from my library but I can't do it in an assembly... thank you for your help
An assembly is made of independent parts that are connected to each other via http://help.solidworks.com/2013/french/SolidWorks/sldworks/c_Assemblies_first_map_topic.htm?id=61b70f9f22824c3d8f312cfa75b1d1da
a welded mechanic is actually several elements connected together via welds that make only one unremovable whole so 1 part with several united bodies http://help.solidworks.com/2013/french/SolidWorks/sldworks/c_Weldments_Overview.htm?id=a7c8bc3549eb4b449f7dd63a24ecf371
3D Sketching Systems allow you to create a 3D sketch (a tube axis to position it at the right latitude and longitude) then via your construction line or you do a sweep via sketches in a library or other extrusion......
The 3D grid is very interesting to make a metal structure if it is well ordered (manageable by a 3D grid). It can only be used in this case (in a part - multi-body) not directly in an assembly. To my knowledge, there is nothing equivalent in assembly or routing. But you can create a new part in the assembly and put the 3D grid on it.
Last clarification, of this 3D grid, you can't directly trace the piping but it can be used as a grid because you can make a 3D sketch that relies on the points