Propane torch solution?

[MarkFresno]

I am changing the shower manifold (valve assembly?) and the brass coupling that attaches to the cast iron hot and cold pipe is rusted. I will hit it with pb blaster but the question I have would it be ok to heat it up the coupling with a propane torch to loosen it up?

 

[SlowDrip]

Should be fine, brass expands much quicker than cast. just be sure not to overdo it because the iron will eventually expand as well.