for tube pins.. use Caig Gold Dx2/ different than the regular gold 100L The Dx2 is good up to 500C temperature!!! cost a lot more though. like $99.
https://www.amazon.com/DeoxITGOLD-Liquid-brush-appl-Tracer/dp/B003D8GUAA
https://www.amazon.com/DeoxITGOLD-Liquid-brush-appl-Tracer/dp/B003D8GUAA