diff --git a/SurfTriMesh.h b/SurfTriMesh.h
index ccff9df..48797d3 100644
--- a/SurfTriMesh.h
+++ b/SurfTriMesh.h
@@ -221,6 +221,7 @@ class SurfTriMesh : public ISurfTriMesh, public IGeoObjRW
       bool GetFacetNormal( int nF, Vector3d& vtN) const override ;
       bool GetFacetArea( int nF, double& dArea) const override ;
       bool GetFacetsContact( int nF1, int nF2, bool& bAdjac, Point3d& ptP1, Point3d& ptP2, double& dAng) const override ;
+      bool RemoveFacet( int nF) override ;
       SurfTriMesh* CloneFacet( int nF) const override ;
       bool SwapFacets( int nF1, int nF2) override ;
       bool GetFacetLocalBBox( int nF, BBox3d& b3Loc, int nFlag = BBF_STANDARD) const override ;
diff --git a/SurfTriMeshFaceting.cpp b/SurfTriMeshFaceting.cpp
index 772efcc..139d50b 100644
--- a/SurfTriMeshFaceting.cpp
+++ b/SurfTriMeshFaceting.cpp
@@ -645,6 +645,8 @@ SurfTriMesh::GetFacetArea( int nF, double& dArea) const
 SurfTriMesh*
 SurfTriMesh::CloneFacet( int nF) const
 {
+   if ( ! IsValid())
+      return nullptr ;
   // alloco la nuova superficie
    PtrOwner<SurfTriMesh> pSTM( CreateBasicSurfTriMesh()) ;
    if ( IsNull( pSTM))
@@ -689,12 +691,40 @@ SurfTriMesh::CloneFacet( int nF) const
    return Release( pSTM) ;
 }
 
+//----------------------------------------------------------------------------
+bool
+SurfTriMesh::RemoveFacet( int nF)
+{
+  // verifico esistenza delle due facce
+   if ( ! IsValid()  ||  nF < 0  ||  nF >= GetFacetCount())
+      return false ;
+
+  // recupero l'elenco dei triangoli della faccia
+   INTVECTOR vTria ;
+   if ( ! GetAllTriaInFacet( nF, vTria))
+      return false ;
+
+  // Rimuovo i triangoli della faccia
+   for ( int i : vTria)
+      RemoveTriangle( i) ;
+
+  // aggiorno le strutture di base dell'oggetto
+   if ( ! DoCompacting())
+      return false ;
+
+  // dichiaro necessità ricalcolo della grafica e di hashgrids3d
+   m_OGrMgr.Reset() ;
+   ResetHashGrids3d() ;
+
+   return true ;
+}
+
 //----------------------------------------------------------------------------
 bool
 SurfTriMesh::SwapFacets( int nF1, int nF2)
 {
   // verifico esistenza delle due facce
-   if ( nF1 < 0  ||  nF1 >= GetFacetCount()  ||  nF2 < 0  ||  nF2 >= GetFacetCount())
+   if ( ! IsValid()  ||  nF1 < 0  ||  nF1 >= GetFacetCount()  ||  nF2 < 0  ||  nF2 >= GetFacetCount())
       return false ;
 
   // recupero gli indici dei triangoli della prima e seconda faccia