However, the outlet of the trap -- a few inches (if you can get that far) from the trap itself should not go over somewhere around 210. Better maybe 205. The inlet can go right up to steam temperature -- 212 -- depending on the radiator and if there are any throttling valves or orifices present.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch