If you want to add this material to the material database, you can use "\Tools\Material Database Editor". Please read the documentation on this tool before you use it (at a minimum you will need two entries for your material: one for "All Codes", and one for your specific Code of interest).

If you don't want to add this material to the material database, then you must specify all of the material properties in the piping input. The expansion coefficient (in units of length/length) can be entered in the Temperature field (see the Help text on this). Note the units are lenght/length, you need to take care of "delta T".