diff --git a/src/GeomAdaptor/GeomAdaptor_Curve.cxx b/src/GeomAdaptor/GeomAdaptor_Curve.cxx
index 89f9f57f98..390673cc31 100644
--- a/src/GeomAdaptor/GeomAdaptor_Curve.cxx
+++ b/src/GeomAdaptor/GeomAdaptor_Curve.cxx
@@ -300,7 +300,14 @@ Standard_Integer GeomAdaptor_Curve::NbIntervals(const GeomAbs_Shape S) const
           BSplCLib::LocateParameter(myBSplineCurve->Degree(),TK,TM,myLast,
                                     myBSplineCurve->IsPeriodic(),
                                     1,Nb,Index2,newLast);
-
+          // Protection against myFirst = UFirst - eps, which located as ULast - eps
+          if (myBSplineCurve->IsPeriodic() && (newLast - newFirst) < Precision::PConfusion())
+          {
+            if (Abs(newLast - myBSplineCurve->FirstParameter()) < Precision::PConfusion())
+              newLast += myBSplineCurve->Period();
+            else
+              newFirst -= myBSplineCurve->Period();
+          }
           // On decale eventuellement les indices  
           // On utilise une "petite" tolerance, la resolution ne doit 
           // servir que pour les tres longue courbes....(PRO9248)
@@ -425,26 +432,36 @@ void GeomAdaptor_Curve::Intervals(TColStd_Array1OfReal& T,
 				      1,Nb,Index2,newLast);
             FirstParam = newFirst;
             LastParam = newLast;
+            // Protection against myFirst = UFirst - eps, which located as ULast - eps
+            if (myBSplineCurve->IsPeriodic() && (LastParam - FirstParam) < Precision::PConfusion())
+            {
+              if (Abs(LastParam - myBSplineCurve->FirstParameter()) < Precision::PConfusion())
+                LastParam += myBSplineCurve->Period();
+              else
+                FirstParam -= myBSplineCurve->Period();
+            }
 	    // On decale eventuellement les indices  
 	    // On utilise une "petite" tolerance, la resolution ne doit 
 	    // servir que pour les tres longue courbes....(PRO9248)
 	    Standard_Real Eps = Min(Resolution(Precision::Confusion()),
 				    Precision::PConfusion()); 
-	    if ( Abs(newFirst-TK(Index1+1))< Eps) Index1++;
-	    if ( newLast-TK(Index2)> Eps) Index2++;
+	    if ( Abs(FirstParam-TK(Index1+1))< Eps) Index1++;
+	    if ( LastParam-TK(Index2)> Eps) Index2++;
 	    
-	    Inter( 1) = Index1;
 	    myNbIntervals = 1;
+
+            TColStd_Array1OfInteger aFinalIntervals(1, Inter.Upper());
+            aFinalIntervals(1) = Index1;
 	    for ( Standard_Integer i=1; i<=NbInt; i++) {
 	      if (Inter(i) > Index1 && Inter(i)<Index2 ) {
 		myNbIntervals++;
-		Inter(myNbIntervals) = Inter(i);
+                aFinalIntervals(myNbIntervals) = Inter(i);
 	      }
 	    }
-	    Inter(myNbIntervals+1) = Index2;
+            aFinalIntervals(myNbIntervals + 1) = Index2;
 	    
 	    for (Standard_Integer I=1;I<=myNbIntervals+1;I++) {
-	      T(I) = TK(Inter(I));
+              T(I) = TK(aFinalIntervals(I));
 	    }
 	  }
 	  break;
diff --git a/src/GeomAdaptor/GeomAdaptor_Surface.cxx b/src/GeomAdaptor/GeomAdaptor_Surface.cxx
index ff860f66e9..621220dae0 100644
--- a/src/GeomAdaptor/GeomAdaptor_Surface.cxx
+++ b/src/GeomAdaptor/GeomAdaptor_Surface.cxx
@@ -438,7 +438,7 @@ void GeomAdaptor_Surface::UIntervals(TColStd_Array1OfReal& T, const GeomAbs_Shap
         (myBSplineSurface->VIso(myBSplineSurface->VKnot(myBSplineSurface->FirstVKnotIndex())),myUFirst,myULast);
       myNbUIntervals = myBasisCurve.NbIntervals(S);
       myBasisCurve.Intervals(T,S);
-      break;
+      return;
     }
     case GeomAbs_SurfaceOfExtrusion:
     {
@@ -448,6 +448,7 @@ void GeomAdaptor_Surface::UIntervals(TColStd_Array1OfReal& T, const GeomAbs_Shap
       {
         myNbUIntervals = myBasisCurve.NbIntervals(S);
         myBasisCurve.Intervals(T,S);
+        return;
       }
       break;
     }
@@ -468,6 +469,7 @@ void GeomAdaptor_Surface::UIntervals(TColStd_Array1OfReal& T, const GeomAbs_Shap
       GeomAdaptor_Surface Sur(myOffSurf->BasisSurface(), myUFirst, myULast, myVFirst, myVLast);
       myNbUIntervals = Sur.NbUIntervals(BaseS);
       Sur.UIntervals(T, BaseS);
+      return;
     }
     case GeomAbs_Plane:
     case GeomAbs_Cylinder:
@@ -500,7 +502,7 @@ void GeomAdaptor_Surface::VIntervals(TColStd_Array1OfReal& T, const GeomAbs_Shap
         (myBSplineSurface->UIso(myBSplineSurface->UKnot(myBSplineSurface->FirstUKnotIndex())),myVFirst,myVLast);
       myNbVIntervals = myBasisCurve.NbIntervals(S);
       myBasisCurve.Intervals(T,S);
-      break;
+      return;
     }
     case GeomAbs_SurfaceOfRevolution:
     {
@@ -511,6 +513,7 @@ void GeomAdaptor_Surface::VIntervals(TColStd_Array1OfReal& T, const GeomAbs_Shap
       {
         myNbVIntervals = myBasisCurve.NbIntervals(S);
         myBasisCurve.Intervals(T,S);
+        return;
       }
       break;
     }
@@ -531,6 +534,7 @@ void GeomAdaptor_Surface::VIntervals(TColStd_Array1OfReal& T, const GeomAbs_Shap
       GeomAdaptor_Surface Sur(myOffSurf->BasisSurface(), myUFirst, myULast, myVFirst, myVLast);
       myNbVIntervals = Sur.NbVIntervals(BaseS);
       Sur.VIntervals(T, BaseS);
+      return;
     }
     case GeomAbs_Plane:
     case GeomAbs_Cylinder:
diff --git a/tests/bugs/modalg_7/bug30273 b/tests/bugs/modalg_7/bug30273
new file mode 100644
index 0000000000..4c29c1c0b3
--- /dev/null
+++ b/tests/bugs/modalg_7/bug30273
@@ -0,0 +1,9 @@
+puts "========"
+puts "0030273: Crash in postprocessing of imported shape."
+puts "========"
+puts ""
+
+pload XDE
+
+stepread [locate_data_file bug30273.stp] res *
+checknbshapes res_1 -solid 176 -face 9968 -shape 69497