The concept and working of a water tight door in a bulkhead on board a ship can be best explained with the help of a diagram which is shown here. The various parts of the water tight door and bulkhead arrangement have been clearly labeled in the diagram and these include the following.
click to enlarge
- Hydraulic cylinder which is necessary for mechanical operation of the door to open and close it.
- Hand pump which is necessary in case of failure of the mechanical system so that there is always a manual option for operation of the door.
- The necessary monitors and controls in the form of alarm and control valve which get activated for safety purposes.
- A remote switch from where the door can be operated as desired in case of emergency or any other situation where direct access is not possible. An indicator at this remote location which shows the status of the door as either being open or closed.
Depending on the location and situation these doors could either open through sliding or like normal hinged doors. The material of construction of these doors is strong and durable material which could be either mild steel or cast steel. It is also required that these doors can operate without fail even when the ship is listed to around 15 degrees which is necessary to ensure safety in an actual emergency situation.
In the actual manufacturing yard, the testing of the door is done either by applying high hose pressure of water and checking for water leakage at the other side or by submerging the door under the required pressure of water before it is actually fitted on to the ship.
It is also worth noting that since cutting of the door in the bulkhead leads to reduction of strength, it is important to counter this effect by providing extra stiffeners and frames to reinforce the same, otherwise water may not get through the water tight door but might rupture the bulkhead itself which would defeat the very purpose of having a water tight door.
