Well to being with suppose I open a new file and start MEP routing with a 21 mm dia pipe size in cooling.
Whenever there's a bend, The Route tool places a 150mm radius bend and the tee size is also quite big as per ASTM Standards.
If I go to the Pipe Bend Object and change the radius to say 15 mm, the Route Tool would again place a bend with 150 mm
Now to use the ASTM Sizes I have had to edit the bend and tee MEP objects using the Open Object option, go to the GDL script, change the radius, connection length, branch length, etc. save them in the Embedded Library.
I have also saved the bend and tee pipe to a local folder for use in other project.
Now before using the Route Tool I once open the Pipe Bend And Tee Objects going to their respective objects in the MEP, Piping, Bend Object and opening them once.
OK. Now I start Routing, the bends with 15 mm radius are placed automatically. When I restart routing from the middle of a pipe Route asks to specify the Tee and I select the custom ASTM tee.
I have tried the "Favorite" approach as suggested by Matthew but that is now working. Maybe I am doing something wrong.
This also works sometimes as many a times the Route tools stops working when trying to continue on a existing route or place a tee in a Middle of a Pipe section.