CARE OF CLOSURES AND FITTINGS

You must keep all closures and fittings in the best possible condition at all times to maintain the ship's watertight integrity feature. Neglected closures and fittings could lead to the loss of your ship.

Faulty gaskets are a main source of leakage through closures. Rubber gaskets are installed in doors, hatches, scuttles, airports, and dogged manholes to provide a tight fit all around. When exposed to oil, grease, heat, or paint, the gaskets begin to deteriorate. Gaskets should be protected from exposure to substances or conditions that cause deterioration. Replace them immediately when they show signs of deterioration. Inspect them frequently to detect hardness, cracks, or permanent set (indentation) greater than 1/8 inch.

Gaskets for bolted manhole covers and other bolted plates differ in size, shape, and material from those used with doors, hatches, scuttles, and dogged manholes. Bolted manhole cover and bolted plate gaskets should be renewed whenever they are found to be in poor condition when the cover is removed. Replacement of these gaskets at this time is particularly important since you cannot tell anything about the condition of the gasket when the manhole/plate is bolted down. The gasket may appear to be perfectly all right when actually it is in a poor condition and is providing a channel for progressive flooding. The replacement gaskets must be of the proper material. The manhole/plate bolts must be tightened up evenly all around. A loosely secured manhole cover can be blown off by an explosion, whereas a cover that is tightly secured will not.

Be careful when moving heavy objects, such as ammunition or machinery, through watertight doors and hatches. If you are careless, you can distort the knife edge or bearing surface of the closure by the impact of the heavy object.

Refer to figure 3-10 while reading the following information.

Figure 3-10.-Watertight door parts.

The compression between a knife edge and a gasket should be checked periodically. If necessary, adjust the closure until the compression specified in the manufacturer's technical manual is reached.

Watertight doors and hatches will retain their efficiency longer and will require less maintenance if you open and close them properly. When you close a door or hatch, secure a dog that is on the OPPOSITE SIDE of the closure from the hinges. Use just enough pressure to keep the door closed. Next, secure two dogs on the hinge side until snug. Then secure all the remaining dogs evenly to ensure an even compression all around. When loosening dogs on watertight doors or hatches, loosen the dogs nearest the hinges first. This will keep the closure from springing and makes it easier to operate the remaining dogs.

A common place for leakage is around dog spindles where the spindles pass through door frames. There is a stuffing box for each dog spindle. The packing in the stuffing box prevents leakage. Inspect the stuffing boxes frequently to ensure that they are in good condition. Tighten the packing gland to give the correct compression of the packing. Repack the dogs when the packing gets hard or deteriorates with age. Occasional adjustment of the dogs is required to compensate for the wearing down of the wedges which the dogs bear down on. When wedges become badly worn, you should either build them up again by gas brazing or replace them.

For a door or hatch to be watertight when it is dogged, the knife edge or bearing surface of

the closure must be centered on the gasket. The knife edge must also bear down on the gasket firmly and evenly all around for the closure to be watertight. The door will not be watertight if either the door or the frame is warped. Also, the closure will not be watertight if the door or hatch is not located correctly on its hinges with respect to the door frame. Other factors governing a closure's watertight feature are whether or not the knife edge is straight and even, whether the retainer strips are secured firmly in place, and whether the dogs are adjusted to provide equal pressure on all of the wedges when the dogs are snugly set up. If any of these parts have an incorrect fit, the frame or knife edges may come into contact with the metallic parts of the closure and thus allow the closure to be closed in a nonwatertight condition.

Some ventilation ducts have covers to isolate the ventilation system. The gaskets on these covers are subject to the same kinds of failure that access closure gaskets are. Many ventilation closures and valves installed in the ventilation ducts lack tightness because of improper seating. These fittings should be inspected on a regular basis. If you lubricate and maintain the fittings on a routine basis, the fittings will stay in good working condition indefinitely.

Throughout the ship, electric cables pass through many watertight boundaries. The watertight integrity is maintained by passing each cable through a packed stuffing tube, as shown in figure 3-11. Usually, several cables will pass through a deck or bulkhead in a small area known

Figure 3-1 I.-Cable penetration through watertightbulkhead.

as a multi-cable transit frame (fig. 3-12). The stuffing tube nearest the center of the group can be repacked only with a great deal of difficulty. It is vital, however, that the packing be replaced when necessary. If you allow bad packing to remain in the stuffing tube, you will have provided a means for progressive flooding to take place.

Leakage can occur where pipes pass through bulkheads and decks. Various methods are used to make the penetration points watertight. Watertight penetration points reduce the chance of progressive flooding.

Airport covers operate basically the same as doors and hatches. You might need to tighten up the dogs on the airport covers. If the dogs are not tight, the glass lens of the airport can be broken by heavy seas or by the movement of the ship. When you secure an airport cover, be sure to bring the hinge pin of the cover all the way out to the end of the hinge. By doing this, you can avoid the possibility of breaking the cover.

To replace the glass lens, drill and tap holes in the workbench top. These holes will need to be the same size as the holding bolts that are fitted through the securing lugs of the airport frame. By drilling and tapping these holes, you will save a considerable amount of time when replacing the glass lens. Once you secure the airport frame to the workbench, you will be able to unscrew the

Figure 3-12.-Multi-cable transit frame. 3-20

retaining ring, After you remove the old glass lens, clean the threads of the frame and the retaining ring. If the frame and ring are made of composition material, apply a light coating of oil or grease to the threads. Before you insert a new glass, embed the edges of the glass in red lead putty or another approved material. When you secure the retaining ring, the putty is forced out evenly all around the glass lens, thereby ensuring a tight fit.

Safety is a major concern in whatever you do. When opening a closure, you can protect yourself by standing on the opposite side from the hinges and loosening the dogs nearest the hinge first. You will then find it easier to loosen the other dogs, and you will not get hurt by the door if there is an explosion within the compartment. The hinges help to keep the door from blowing open. If you are on the hinge side of the door when an explosion occurs, you will be caught between the door and the bulkhead.

Each closure has a safety device. Some hatches have stanchions; others have locking latches. Both devices use toggle pins to secure them in place. Be sure that the toggle pins are in place at all times when the hatch is open. Watertight scuttles have a safety device known as a bracing link assembly. Make sure that the bracing link assembly is in good operating condition at all times. When exiting a compartment through a scuttle, do not grab hold of the scuttle to pull yourself through. If the bracing link assembly fails to lock, the scuttle will fall on your head or fingers, causing considerable injury. A door catch is installed for each shipboard door. When a door is to be left open for a period of time, use the door catch. The movement of the ship could cause the door to slam shut. A door slamming shut will damage the door's gasket and could seriously injure a person. Most personnel injuries are not caused by the closure's design, but rather by an individual's carelessness.