Index: Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs
===================================================================
diff -u -r9395ef9c44963521a3d8a81cda0a040e7d08c589 -r61a49a907749e8cf46ce15b227108fd42ffece87
--- Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision 9395ef9c44963521a3d8a81cda0a040e7d08c589)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision 61a49a907749e8cf46ce15b227108fd42ffece87)
@@ -544,16 +544,12 @@
 
         private void CalculateAll(PipingFailureMechanismContext failureMechanismContext)
         {
-            IEnumerable<PipingCalculation> calculations = GetAllPipingCalculations(failureMechanismContext.WrappedData);
-
-            CalculateAll(calculations, failureMechanismContext.Parent);
+            CalculateAll(failureMechanismContext.WrappedData.CalculationsGroup, failureMechanismContext.Parent);
         }
 
         private void CalculateAll(CalculationGroup group, PipingCalculationGroupContext context)
         {
-            PipingCalculation[] calculations = group.GetCalculations().OfType<PipingCalculation>().ToArray();
-
-            CalculateAll(calculations, context.AssessmentSection);
+            CalculateAll(context.WrappedData, context.AssessmentSection);
         }
 
         private static void ValidateAll(IEnumerable<PipingCalculation> pipingCalculations, IAssessmentSection assessmentSection)
@@ -564,15 +560,11 @@
             }
         }
 
-        private void CalculateAll(IEnumerable<PipingCalculation> calculations,
+        private void CalculateAll(CalculationGroup calculationGroup,
                                   IAssessmentSection assessmentSection)
         {
             ActivityProgressDialogRunner.Run(
-                Gui.MainWindow,
-                calculations
-                    .Select(pc => new PipingCalculationActivity(pc,
-                                                                GetNormativeAssessmentLevel(assessmentSection, pc)))
-                    .ToList());
+                Gui.MainWindow, PipingCalculationActivityFactory.CreateCalculationActivities(calculationGroup, assessmentSection));
         }
 
         #region PipingSurfaceLinesContext TreeNodeInfo
@@ -665,11 +657,6 @@
                           .Build();
         }
 
-        private static IEnumerable<PipingCalculation> GetAllPipingCalculations(PipingFailureMechanism failureMechanism)
-        {
-            return failureMechanism.Calculations.OfType<PipingCalculation>();
-        }
-
         private static object[] FailureMechanismEnabledChildNodeObjects(PipingFailureMechanismContext context)
         {
             PipingFailureMechanism wrappedData = context.WrappedData;
@@ -803,9 +790,8 @@
 
         private void PerformCalculation(PipingCalculation calculation, PipingCalculationScenarioContext context)
         {
-            ActivityProgressDialogRunner.Run(Gui.MainWindow,
-                                             new PipingCalculationActivity(calculation,
-                                                                           GetNormativeAssessmentLevel(context.AssessmentSection, calculation)));
+            ActivityProgressDialogRunner.Run(Gui.MainWindow, 
+                                             PipingCalculationActivityFactory.CreateCalculationActivity(calculation, context.AssessmentSection));
         }
 
         private StrictContextMenuItem CreateUpdateEntryAndExitPointItem(PipingCalculationScenarioContext context)