Autocad Plant3D Pipe tessellation issue

[Ravi_Lagad]

I have created a  Autocad Plant3D test plug-In using C# . In this code, I have to access triangulated data of a pipe object.

It gets compiled, but at run time throws an exception as in attached image.

Database db = Application.DocumentManager.MdiActiveDocument.Database;
using (Transaction transaction = db.TransactionManager.StartTransaction())
            {
                BlockTableRecord btRecord = (BlockTableRecord)transaction.GetObject(SymbolUtilityServices.GetBlockModelSpaceId(db), OpenMode.ForWrite);
                foreach (ObjectId id in btRecord)
                {
                    DBObject tDBObject = (DBObject)transaction.GetObject(id, OpenMode.ForWrite);
                    if (tDBObject is Pipe)
                    {
                        Pipe tpipe = tDBObject as Pipe;
                        tBrep = new Brep(tpipe);            //Throws an exception on this line.

                    }

                }

           }

Please let me know where i am making a mistake and also, if any other way to access Pipe tessellation.