As can be seen on Mako, they superglue the joints together with a roller
I'm pretty sure they just bolt it together, no welding. That's the level of perfection needed behind roller coasters! I know they welded The Smiler... but that's because it didn't fit
That's why you spend money on B&M, not Gerstlauer.
My hype levels are building though with each piece that's completed out on the lake now though! August, please hurry up!