Oh okay I didn't know about that Encounters pack. Technically, you have to own the blocks, you want to use. And making a npc hydrogen tank yours means to grind it down a little bit (below the blue line) and weld it again. I don't know if the tank loses all its hydrogen if you grind it down that little bit.
Maybe the hydrogen stays inside if you don't grind it below the red line?

What could also be worth a try is using a merge block to merge the ship with your station. It's possible that the blocks' ownership will be reset on merging so you can access them. You could then just unmerge the ship again. (you will have to convert it to ship again after unmerging)
But I would test this in creative mode first, before risking anything in survival mode. I didn't play SE for quite some time and I'm not sure how things behave ingame at the moment.

I have question about npc version of this craft from OKI encounters pack, lets say that i can capture it undamaged with all hydrogen remaining. Can i transfer it from NPC tanks to storage on my own base via connectors? Tried several ways but it dint worked for me.

dude nice i was think of makeing something like this