1993 fuel tank vent lines

How's it going people?

I'm changing the fuel tank on my burban and I have a question. I've gotten all new stuff IE: sending unit, pump, lines and tank. The only thing I need to save from my old tank is the two plastic vents that are on top of the tank. I'm able to turn them counter clockwise a half turn but I can't seem to get them out. I'm a little scared that if I pry on them I might break them. Does anyone know of anyway to get these out without breaking them?

Thanks,
Richard