There are several choices or methods depending on the application. If not a high temp (>800 F), pressure retaining application, E309-16 will work. INCO 182 (ENiCrFe-3) can also be used if differential thermal expansion is a concern. I've also used E310-15 in some marine applications, but it could be used in some other applications. If your just talking about structural steel (which is what A572 Gr. 50 is mostly used for), the E309 will work fine.

Marty