How do I make a self-intersecting solid, not have those surfaces inside?

Want to get rid of the self-intersecting parts of this, so that I have a perfectly hollow inside. Please help.

Split the part and then union the intersecting parts before the other parts or shrinkwrap everything. Shrinkwrap is not available in Rhino 6 however.

Is this is for 3D printing?

Yes, But before 3D printing, I need to add a lot of details inside. Also, I realized, it’s Rhino8 that I am using.

@martinsiegrist Spit using what for the cutting? It’s intersecting itself, what do you recommend I use for rhino to understand how I need those surfaces to be split?

You would have to use a surface on the opposite side of the zone where the pipe intersects.

Post your rhino file if you can’t get it to work.