Boolean Union failed!

Hi Rhinofriends!

I tried Boolean Union on the 2 closed surfaces several times but it keeps on failing.
Can anybody help me?

hekje.3dm (2.1 MB)

Look carefuly at your model.

When it’s corrected, don’t use booleans, just extract the surfaces that caps the two polysurfaces, such as those:

And then join the two parts, using the Join command.