Index: Application/Ringtoets/src/Application.Ringtoets.Storage/Read/FailureMechanismEntityReadExtensions.cs
===================================================================
diff -u -r36d4b4090a4169cc8d25ede0029a3244df8fe74d -r899d227631395ebeb5154719f7b92a42ddbc6f96
--- Application/Ringtoets/src/Application.Ringtoets.Storage/Read/FailureMechanismEntityReadExtensions.cs	(.../FailureMechanismEntityReadExtensions.cs)	(revision 36d4b4090a4169cc8d25ede0029a3244df8fe74d)
+++ Application/Ringtoets/src/Application.Ringtoets.Storage/Read/FailureMechanismEntityReadExtensions.cs	(.../FailureMechanismEntityReadExtensions.cs)	(revision 899d227631395ebeb5154719f7b92a42ddbc6f96)
@@ -35,6 +35,7 @@
 using Application.Ringtoets.Storage.Read.StabilityPointStructures;
 using Application.Ringtoets.Storage.Read.StabilityStoneCover;
 using Application.Ringtoets.Storage.Read.WaveImpactAsphaltCover;
+using Core.Common.Base.Data;
 using Ringtoets.ClosingStructures.Data;
 using Ringtoets.Common.Data;
 using Ringtoets.Common.Data.Calculation;
@@ -590,10 +591,26 @@
         /// <param name="entity">The <see cref="FailureMechanismEntity"/> to create <see cref="MacroStabilityOutwardsFailureMechanism"/> for.</param>
         /// <param name="failureMechanism">The target of the read operation.</param>
         /// <param name="collector">The object keeping track of read operations.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any input parameter is <c>null</c>.</exception>
         internal static void ReadAsMacroStabilityOutwardsFailureMechanism(this FailureMechanismEntity entity,
                                                                           MacroStabilityOutwardsFailureMechanism failureMechanism,
                                                                           ReadConversionCollector collector)
         {
+            if (entity == null)
+            {
+                throw new ArgumentNullException(nameof(entity));
+            }
+
+            if (failureMechanism == null)
+            {
+                throw new ArgumentNullException(nameof(failureMechanism));
+            }
+
+            if (collector == null)
+            {
+                throw new ArgumentNullException(nameof(collector));
+            }
+
             entity.ReadCommonFailureMechanismProperties(failureMechanism, collector);
             entity.ReadMacroStabilityOutwardsMechanismSectionResults(failureMechanism, collector);
             MacroStabilityOutwardsFailureMechanismMetaEntity metaEntity = entity.MacroStabilityOutwardsFailureMechanismMetaEntities.Single();
@@ -835,12 +852,30 @@
         /// <param name="entity">The <see cref="FailureMechanismEntity"/> to create <see cref="PipingStructureFailureMechanism"/> for.</param>
         /// <param name="failureMechanism">The target of the read operation.</param>
         /// <param name="collector">The object keeping track of read operations.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any input parameter is <c>null</c>.</exception>
         internal static void ReadAsPipingStructureFailureMechanism(this FailureMechanismEntity entity,
                                                                    PipingStructureFailureMechanism failureMechanism,
                                                                    ReadConversionCollector collector)
         {
+            if (entity == null)
+            {
+                throw new ArgumentNullException(nameof(entity));
+            }
+
+            if (failureMechanism == null)
+            {
+                throw new ArgumentNullException(nameof(failureMechanism));
+            }
+
+            if (collector == null)
+            {
+                throw new ArgumentNullException(nameof(collector));
+            }
+
             entity.ReadCommonFailureMechanismProperties(failureMechanism, collector);
             entity.ReadPipingStructureMechanismSectionResults(failureMechanism, collector);
+
+            failureMechanism.N = (RoundedDouble) entity.PipingStructureFailureMechanismMetaEntities.Single().N;
         }
 
         private static void ReadPipingStructureMechanismSectionResults(this FailureMechanismEntity entity,