3D Tetrahedral Mesh

[KQEFEM]

Hi all,
I am trying to mesh this (FL-5X16KF: FL-5X16KF | 1 | 5-Way | DN16KF | 19.1 stp_file) in 3D and have noticed that it fails with the errors:

 PLC Error:  A segment and a facet intersect at point
Error   : PLC Error:  A segment and a facet intersect at point
.Error   : Invalid boundary mesh (segment-facet intersection) on surface 2, intersection (-1.86018,-8.39638,25.9704)
.Error   : No elements in volume 1 2 3 4 5 6 7 8 9 10 
.Error   : ------------------------------
.Error   : Mesh generation error summary
.Error   :     0 warnings
.Error   :     3 errors
.Error   : Check the full log for details

These files are directly from the manufacturers website so they should be of good quality.

From what I can see the code I use should work (python API):

gmsh.initialize()
gmsh.model.add(model_name)
gmsh.merge(filepath_geom)
gmsh.model.geo.synchronize()
gmsh.option.setNumber("Mesh.Algorithm3D", 1)
gmsh.option.setNumber("Mesh.CharacteristicLengthMin", self.mesh_size)
gmsh.model.mesh.generate(3)
gmsh.write(mesh_file)
gmsh.finalize()

I am trying to mesh the interior walls of the object but wonder if it is a code issue or a CAD problem and how to 'fix' the problem.

Note: I have tried reducing the mesh_size but this has no effect. I have also tried using the GUi and this only meshes in 2D.