Surface to Solid watertight problems

[RIAL]

Hello all,

 

I am trying to create a solid joining the surfaces I have but it keeps telling me "no watertight volume created".  I tried everything, making the geomtry smoother, dividing the solid in sections, but there are some that aren't supposed to be closed to get a watertight volume. I also went joint by joint checking if there are any gaps but I couldn't find the problem. 

 

I would appreaciate some help here

 

I attach the model. 

 

Thank you

Draft tube - SOLIDS.dwg

[lrm]

Duplicate post and solution here.

[SLW210]

Odd solution, but nothing Autodesk surprises me!