No i am not drunk and it is not a design flaw.................................
In some of the ships the non-return overboard valve especially for the OWS bilge overboard v/v and the boiler blow down v/v might be placed in reverse ie. the direction of valve will be from outward to inward direction.
The main reason for such a odd arrangement is as the ows overboard v/v and boiler blow down valve are frequently used (opened and closed frequently depending on ships operation).
As the direction of the valve is reversed it prevents sea water entering the engine room when a basic maintenance such as gland replacement is done provided the valve is shut and it holds.