Index: src/Plugins/Wti/Wti.Calculation/Piping/PipingCalculation.cs
===================================================================
diff -u -r7245ba23f1a696b772b9dc57ea4f92ac822c17f3 -rff0d3e86209edd5224336bd805466a1c062b00a5
--- src/Plugins/Wti/Wti.Calculation/Piping/PipingCalculation.cs	(.../PipingCalculation.cs)	(revision 7245ba23f1a696b772b9dc57ea4f92ac822c17f3)
+++ src/Plugins/Wti/Wti.Calculation/Piping/PipingCalculation.cs	(.../PipingCalculation.cs)	(revision ff0d3e86209edd5224336bd805466a1c062b00a5)
@@ -60,6 +60,10 @@
             {
                 throw new PipingCalculationException(e.Message);
             }
+            catch (PipingException<SellmeijerBaseCalculator> e)
+            {
+                throw new PipingCalculationException(e.Message);
+            }
         }
 
         private HeaveCalculator CalulateHeave()