Closed .igs input converts to open .stl

[natchoeli]

Hi!

I have tried the pyiges library with a closed .igs polysurface made of 8 surfaces. The final .stl has some of the edges between surfaces non-manifold, even if I activate the merge=True option.

Is it possible to solve the issue somehow? I would like to obtain a closed polysurface, suitable for boolean operations.

Code:
iges = pyiges.read('test.igs')
mesh = iges.to_vtk(bsplines=True, surfaces=True, merge=True, delta=0.01)
mesh.save('test.stl')

Find attached the test.igs file used.
test.zip