Index: Ringtoets/Piping/src/Ringtoets.Piping.Data/PipingFailureMechanism.cs
===================================================================
diff -u -r6b639dc3027f47a35279aa8b4925ca5ed1c71b5f -r6bcbd610ececdc293a8883b50448f369e1fa4a25
--- Ringtoets/Piping/src/Ringtoets.Piping.Data/PipingFailureMechanism.cs	(.../PipingFailureMechanism.cs)	(revision 6b639dc3027f47a35279aa8b4925ca5ed1c71b5f)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Data/PipingFailureMechanism.cs	(.../PipingFailureMechanism.cs)	(revision 6bcbd610ececdc293a8883b50448f369e1fa4a25)
@@ -4,6 +4,7 @@
 
 using Ringtoets.Common.Data;
 using Ringtoets.Common.Placeholder;
+using Ringtoets.Piping.Data.Properties;
 
 using RingtoetsCommonDataResources = Ringtoets.Common.Data.Properties.Resources;
 
@@ -23,7 +24,9 @@
             SurfaceLines = new ObservableList<RingtoetsPipingSurfaceLine>();
             SoilProfiles = new ObservableList<PipingSoilProfile>();
             BoundaryConditions = new InputPlaceholder(RingtoetsCommonDataResources.FailureMechanism_BoundaryConditions_DisplayName);
-            Calculations = new List<IPipingCalculationItem> { new PipingCalculation() };
+            var pipingCalculationGroup = new PipingCalculationGroup(Resources.PipingFailureMechanism_Calculations_DisplayName, false);
+            pipingCalculationGroup.Children.Add(new PipingCalculation());
+            CalculationsGroup = pipingCalculationGroup;
             AssessmentResult = new OutputPlaceholder(RingtoetsCommonDataResources.FailureMechanism_AssessmentResult_DisplayName);
         }
 
@@ -50,7 +53,7 @@
         /// <summary>
         /// Gets all available piping calculations.
         /// </summary>
-        public ICollection<IPipingCalculationItem> Calculations { get; private set; }
+        public PipingCalculationGroup CalculationsGroup { get; private set; }
 
         /// <summary>
         /// Gets the calculation results for this failure mechanism.