There may be no particular ASME P, or S Number assigned for your particular alloy, and, thus, the base material would be "unassigned". In that case, you would record the base metal identity in the PQR data, per ASME, and subsequent WPS(s) would be restricted to that particular material. See QW-420, QW-424.
Hi wonderweld
You have to remember that ASME IX is part of the ASME Boiler and pressure vessel code. As such, it only really covers materials that will typically be used in such applications. It is my bet that Alloy 2219 is not usually used in these applications. As noted in one of the other posts, you can just make it "unassigned" and move further from there. At any rate, it would be easier if you had an ASTM spec and/or an UNS number. Then it would be easier to search for it in ASME IX.
Regards
Niekie Jooste
Fabristruct Solutions