Propane Piping ?

Galvanized fittings (the shiny one) can be used with brass fittings in most building code jurisdictions. There is a very slight possibility of galvanic corrosive action which could potentially damage the threads of the galvanized fitting. However, it is so insignificant, that it would take many decades for the effects of galvanic action to take place. Just do a periodic leak tet and you should be fine. Plumbers interconnect brass, galvanized and black pipe all the time.