diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
index 14ef62fc3..1c9d3be10 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
@@ -52,8 +52,6 @@ public class HoursGroup extends IntegrationEntity implements Cloneable,
 
     private static final Log LOG = LogFactory.getLog(HoursGroup.class);
 
-    private String code;
-
     private ResourceEnum resourceType = ResourceEnum.WORKER;
 
     private Integer workingHours = 0;
@@ -88,11 +86,11 @@ public class HoursGroup extends IntegrationEntity implements Cloneable,
 
     public static HoursGroup createUnvalidated(String code,
             ResourceEnum resourceType, Integer workingHours) {
-        HoursGroup result = new HoursGroup();
+        HoursGroup result = create(new HoursGroup());
         result.setCode(code);
         result.setResourceType(resourceType);
         result.setWorkingHours(workingHours);
-        return create(result);
+        return result;
     }
 
     /**
@@ -158,7 +156,7 @@ public class HoursGroup extends IntegrationEntity implements Cloneable,
     private HoursGroup(OrderLine parentOrderLine) {
         this.parentOrderLine = parentOrderLine;
         String code = parentOrderLine.getCode();
-        this.code = code != null ? code : "";
+        this.setCode(code != null ? code : "");
         this.setOrderLineTemplate(null);
     }
 
@@ -167,15 +165,6 @@ public class HoursGroup extends IntegrationEntity implements Cloneable,
         this.setParentOrderLine(null);
     }
 
-    @NotEmpty(message = "code not specified")
-    public String getCode() {
-        return code;
-    }
-
-    public void setCode(String code) {
-        this.code = code;
-    }
-
     public ResourceEnum getResourceType() {
         return resourceType;
     }
@@ -415,6 +404,13 @@ public class HoursGroup extends IntegrationEntity implements Cloneable,
         return Registry.getHoursGroupDAO();
     }
 
+    @Override
+    public boolean checkConstraintUniqueCode() {
+        // the automatic checking of this constraint is avoided because it uses
+        // the wrong code property
+        return true;
+    }
+
     public static void checkConstraintHoursGroupUniqueCode(OrderElement order) {
         HoursGroup repeatedHoursGroup;
 
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/ws/common/impl/OrderElementConverter.java b/navalplanner-webapp/src/main/java/org/navalplanner/ws/common/impl/OrderElementConverter.java
index f1438747d..cd087f216 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/ws/common/impl/OrderElementConverter.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/ws/common/impl/OrderElementConverter.java
@@ -252,9 +252,14 @@ public final class OrderElementConverter {
         }
         OrderElement orderElement = toEntityExceptCriterionRequirements(
                 orderVersion, orderElementDTO, configuration);
+        // Validate OrderElement.code and HoursGroup.code must be unique
+        Order.checkConstraintOrderUniqueCode(orderElement);
+        HoursGroup.checkConstraintHoursGroupUniqueCode(orderElement);
+
         if (configuration.isCriterionRequirements()) {
             addOrCriterionRequirements(orderElement, orderElementDTO);
         }
+
         return orderElement;
     }
 
@@ -356,6 +361,7 @@ public final class OrderElementConverter {
             OrderElementDTO orderElementDTO,
             ConfigurationOrderElementConverter configuration)
             throws ValidationException {
+
         Validate.notNull(parentOrderVersion);
         OrderElement orderElement;
 
@@ -443,10 +449,6 @@ public final class OrderElementConverter {
             addAdvanceMeasurements(orderElement, orderElementDTO);
         }
 
-        // Validate OrderElement.code and HoursGroup.code must be unique
-        Order.checkConstraintOrderUniqueCode(orderElement);
-        HoursGroup.checkConstraintHoursGroupUniqueCode(orderElement);
-
         return orderElement;
     }
 
diff --git a/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java b/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java
index e86889bf3..a36242b0c 100644
--- a/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java
+++ b/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java
@@ -339,8 +339,8 @@ public class OrderElementServiceTest {
 
         List<ConstraintViolationDTO> constraintViolations = instanceConstraintViolationsList
                 .get(0).constraintViolations;
-        // Mandatory fields: code, workingHours
-        assertThat(constraintViolations.size(), equalTo(2));
+        // Mandatory fields: code
+        assertThat(constraintViolations.size(), equalTo(1));
 
         for (ConstraintViolationDTO constraintViolationDTO : constraintViolations) {
             assertThat(constraintViolationDTO.fieldName, anyOf(mustEnd("code"),