diff --git a/src/main/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/pTphaseEnvelope.java b/src/main/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/pTphaseEnvelope.java
index 5b0fda66b9..950bbcf718 100644
--- a/src/main/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/pTphaseEnvelope.java
+++ b/src/main/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/pTphaseEnvelope.java
@@ -223,6 +223,7 @@ public void run() {
           new sysNewtonRhapsonPhaseEnvelope(system, 2, system.getPhase(0).getNumberOfComponents());
       startPres = system.getPressure();
       nonLinSolver.setu();
+
       for (np = 1; np < 9980; np++) {
         try {
           // solves the np point of the envelope
@@ -233,6 +234,7 @@ public void run() {
           // double TT = system.getPhase(0).getTemperature();
           // double PP = system.getPhase(0).getPressure();
         } catch (Exception e0) {
+
           // the envelope crushed.
           // this part keeps the old values
           // restarts the envelope from the other side
@@ -521,6 +523,7 @@ public void run() {
        */
     } catch (Exception ex) {
       logger.error(ex.getMessage(), ex);
+      throw ex;
     }
   }
 
diff --git a/src/test/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/PTphaseEnvelopeTest.java b/src/test/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/PTphaseEnvelopeTest.java
new file mode 100644
index 0000000000..4dd78b6c16
--- /dev/null
+++ b/src/test/java/neqsim/thermodynamicOperations/phaseEnvelopeOps/multicomponentEnvelopeOps/PTphaseEnvelopeTest.java
@@ -0,0 +1,73 @@
+package neqsim.thermodynamicOperations.phaseEnvelopeOps.multicomponentEnvelopeOps;
+
+import neqsim.thermodynamicOperations.ThermodynamicOperations;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PTPhaseEnvelopeTest {
+    static neqsim.thermo.system.SystemInterface testSystem = null;
+    static ThermodynamicOperations testOps = null;
+
+    @BeforeEach
+    void setUp() {
+        testSystem = new neqsim.thermo.system.SystemSrkEos(298.0, 50.0);
+    }
+
+    /**
+     * Test method for {@link neqsim.thermodynamicOperations.phaseEnvelopeOps.multicomponentEnvelopeOps.pTphaseEnvelope}.
+     */
+    @Test
+    void testDewP() {
+        testSystem.addComponent("nitrogen", 0.01);
+        testSystem.addComponent("CO2", 0.01);
+        testSystem.addComponent("methane", 0.98);
+        testSystem.setMixingRule("classic");
+
+        testOps = new ThermodynamicOperations(testSystem);
+        testOps.TPflash();
+        testSystem.initProperties();
+        testOps.calcPTphaseEnvelope();
+        double[] dewPointPressures = testOps.get("dewP");
+        double[] expectedDewPointPressures =
+                new double[]{
+                        1.1051709180756477, 1.2214027581601699, 1.3498588075760032, 1.4918246976412703,
+                        1.6652911949458864, 1.8794891289619104, 2.1418131227502055, 2.4690864123141987,
+                        2.881197018974799, 3.404779997613969, 4.075230307874481, 4.938583914869986, 6.051801019586486,
+                        7.477304695462727, 9.260793952051571, 11.364101185282063, 13.480106047577934, 14.53423776629387,
+                        13.607498029406681, 11.181207439509638, 9.189487040488075, 9.612827246459474,
+                        10.706126846063928, 12.501491987760147, 15.075672692089958, 18.51283799420178,
+                        23.330378296334104, 29.71319711031059, 37.25532259549197, 43.660805656603934, 45.75836660678656,
+                        46.42490219574348, 46.83203503669948, 46.869568345957006, 46.903557772489435
+                };
+        System.out.println(Arrays.toString(dewPointPressures));
+        assertArrayEquals(expectedDewPointPressures, dewPointPressures, 10E-5);
+
+    }
+
+    @Test
+    void testFailingCaseWithWater() {
+        testSystem.addComponent("nitrogen", 0.04);
+        testSystem.addComponent("CO2", 0.06);
+        testSystem.addComponent("methane", 0.80);
+        testSystem.addComponent("water", 0.00000000001);
+
+        testSystem.setMixingRule("classic");
+
+        testOps = new ThermodynamicOperations(testSystem);
+        testOps.TPflash();
+        testSystem.initProperties();
+
+
+        Exception exception = assertThrows(ArrayIndexOutOfBoundsException.class, () -> testOps.calcPTphaseEnvelope());
+
+        String expectedMessage = "Index -1 out of bounds for length 10000";
+        assertTrue(exception.getMessage().contains(expectedMessage));
+
+    }
+
+
+}