@Cucoo
It depends.
Due to the mission where he had to blow up The Extractor, he needed to modify his armor so that it could survive temperatures up to 60,000 - 100,000 *F. It still damaged his shields, but thanks to the Titus Shield Reinforcements, along with a boost from a magical grimoire given to him by Patchouli, and a buff from Byakuren, he was able to survive the heat.
Of course, Nera was able to as well, just by using ice to keep herself cool. Don't ask me how ice could survive temperatures capable of vaporizing every known element on the periodic table in a near instant, I simply handwaved it, due to me being under stress. -_-;
I would have said something, but it seemed as if Kristia was simply trying to get a piece of the action, and as such, Nera followed John into a superheated engine that would have vaporized him if it wasn't for all the enchantments, so I didn't say anything.
The realist in me is dying. :p
(My inner realist.)Spoiler

It's just that realistically, the ice should have exploded like a bomb when subjected to such temperatures. To get a rough idea what happens, look up ice/Thermite bombs.