If I have a 1" pipe that is 50 meters long made out of stainless steel.

Its at ambient temp. Then you flow liquid O2 at -186 C through it. If it takes about 30 minutes to bring the pipe from ambient to operation temp of -186C. How do I calculate the amount of flash?

Yes I am still learning the stuff.

What do I need to know and how do I do it?

Thank you