Index: Ringtoets/Piping/src/Ringtoets.Piping.Data/DerivedPipingInput.cs
===================================================================
diff -u -rf5e6d6dbc89bb2059883a47a7be9ab944b4825d6 -re1664eb0060cbe4da4d1ab134f847b20ee1415be
--- Ringtoets/Piping/src/Ringtoets.Piping.Data/DerivedPipingInput.cs	(.../DerivedPipingInput.cs)	(revision f5e6d6dbc89bb2059883a47a7be9ab944b4825d6)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Data/DerivedPipingInput.cs	(.../DerivedPipingInput.cs)	(revision e1664eb0060cbe4da4d1ab134f847b20ee1415be)
@@ -287,7 +287,7 @@
             }
         }
 
-        private bool HasUniqueShiftAndDeviationSaturatedWeightDefinition(IList<PipingSoilLayer> consecutiveAquitardLayers, int deviationNumberOfDecimals, int shiftNumberOfDecimals)
+        private static bool HasUniqueShiftAndDeviationSaturatedWeightDefinition(IList<PipingSoilLayer> consecutiveAquitardLayers, int deviationNumberOfDecimals, int shiftNumberOfDecimals)
         {
             if (!consecutiveAquitardLayers.Any())
             {
@@ -305,7 +305,7 @@
                 shiftNumberOfDecimals));
         }
 
-        private bool AreShiftAndDeviationEqual(PipingSoilLayer currentLayer, PipingSoilLayer baseLayer, int deviationNumberOfDecimals, int shiftNumberOfDecimals)
+        private static bool AreShiftAndDeviationEqual(PipingSoilLayer currentLayer, PipingSoilLayer baseLayer, int deviationNumberOfDecimals, int shiftNumberOfDecimals)
         {
             var belowPhreaticLevelDeviationBase = new RoundedDouble(deviationNumberOfDecimals, baseLayer.BelowPhreaticLevelDeviation);
             var belowPhreaticLevelShiftBase = new RoundedDouble(shiftNumberOfDecimals, baseLayer.BelowPhreaticLevelShift);