Convert closed curves segments into one solid object

I have a file created in Tekla, but the cylinders come out as closed curves segments (like a mesh)
Is there any procedure or a series of commands that I can convert these closed curves segments into one solid cylinder? with no mesh at all.
Thanks to everyone that submit any suggestion I really appreciate all the help I can get

Hello - please post a file, or send to and someone will try to help.


Excellent! I will do that

Please take a look for the issue I have.
Piping-3d.dgn (4.6 MB)


Hi Sam - that does look like quite a nuisance - you can do it but it will take some fussing. For the piping, you can use the Circle command to builds circles with the ‘ThreePoint’ option snapping to ends of the line segments. Then Extrude and Revolve the curves to build up the pipe. Some objects can be made as Revolves -

What is the goal here? Why do you need the objects in Rhino? This seems like a hard way to get information about quite simple objects - are the pipe centerlines available?


Hi Pascal,
Thanks for your interest about this problem.
Sorry if I didn’t explained it.
I have a 3D file already that I extracted from a Tekla model, as a dgn, but it came like I showed in one of the pictures, like a mesh or closed curves segments, whatever they are.
I have used many times for conversions from one file to another format, I don’t use it for modeling at all.
I am looking for a way that I can convert the extracted (mesh file) to a solid object to be able to get just the outline in the different orientation views.
I hope this extend my request.

Hi Sam - in case it helps, you can get back to the meshes as follows:
Select a grouped set of lines.
'Explodeand with the lines still selected runMeshFromLines`


Hi Pascal, That was good workaround like 75% what I’m trying to do.
I did the exploding, then the MeshFromLines and then MeshOutlined.

My question will be:
Can I convert the mesh to solid that only will display the outline ? So I can get a 3d model
But you are a genius so far so good.
Regards, Sam

Pascal, When I select one of the objects the property shows that they are open curves, grouped. does this give you another clue to do something else?

I have something that it worked partially, pipes are OK but elbows still with mesh, I export the pipes from Tekla using a plugin to export them as stp files, I opened them with MIcrostation and looks better as it shows in the attached snapshot.