probably not abs, but it's been done with peek.

Porosity isn't your biggest problem. Layer adhesion is.
3D printed Abs just isn't that great.

PEEK is probably your best bet - but I think you'd need to upgrade the hotend to something that can take 400c
From what i can see on the fusion3d website they are just using standard e3d hotends.
A bit cheeky for the price they're charging, these days most industrial machine have a hi-temp option.

Because of the way fdm machines work, in individual layers, the vast majority of materials would not make reliable pressure vessels.
You could probably also do it with flexible pla or TPU filaments. They're layer bonding is much much better and they also would have less porosity, as well as a little flexibility to allow for minimal expansion rather than cracking.

It would probably be worth your while having a chat with ninjatek. Something like their armadillo (polyurethane) might conceivably work, or the stiffer variations of ninjaflex.

I suspect it's doable - but you won't be using cheap crap like abs :-)