Solid union

Hello Guys,

A have a problem again, but this time its about the union function with solids/meshes.

In my definition i have multiple hexagonal surfaces at the edges connected and want create closed rounded pipes starting from the edgepoints and going by a length to center of the surfaces. Tis is ok and work.

Now a want to union the overlapping pipes to one and use for it the solid union command.

But it wont work. if i explode the tree and union every overlapping pipes than it works. Thats fine, but in my definition the amound of Pipes is over ten so it is ridiculous to work with it. Is it possible to union them without an explosion??

I flattened the pipes and should work, but it give me an error and do nothing.

Need help!!