Chapter 9-MACHINERY ARRANGEMENT AND PLANT LAYOUT 



off. A clearing line branches off from the re- 

 circulating line. Valves in the recirculating 

 line and in the clearing line permit fuel oil to 

 be discharged to the suction side of the fuel oil 

 service pump or to the contaminated oil settling 

 tank (or overboard). A check valve in the re- 

 circulating line prevents the back flow of oil 

 from the fuel oil suction main; another check 

 valve at the connection of the clearing line and 

 the contaminated oil settling tank prevents back 

 flow from the contaminated oil settling tank 

 through the clearing line and into the recirculat- 

 ing line. 



The valves just listed are typically found in 

 fuel oil service systems on ships which use 

 straight-through-flow atomizers. Where return- 

 flow atomizers are used, additional valves are 

 required in the fuel oil service system to con- 

 trol the return flow of oil and (in some installa- 

 tions) to control the flow of oil through a cooler. 

 Where automatic boiler controls are installed, 

 still more valves are required in the fuel oil 

 service system; these include fuel oil supply 

 and return valves which are operated by the 

 boiler control system. 



BALLASTING SYSTEMS 



The ballasting system allows the controlled 

 flooding of certain designated tanks, when such 

 flooding is required for stability control. All 

 tanks that are designated as fuel oil and ballast 

 tanks (and also certain voids) may be flooded 

 by the ballasting system. Sea water is used for 

 ballasting; it may be taken from the firemain 

 or it may be taken directly from sea chests. 



Combined ballasting and drainage systems 

 are arranged so that all designated compart- 

 ments and tanks can be ballasted either separate- 

 ly or together and drained either separately or 

 together. Drainage pumps or eductors are used 

 to remove the ballast water. 



DIESEL OIL AND JP-5 SYSTEMS 



Diesel oil systems are found even on steam- 

 driven ships. Ships that carry large supplies 

 of diesel oil have fairly complex diesel oil 

 systems which are quite similar to the boiler 

 fuel oil systems already described. Although 

 the diesel oil systems are separate from the 

 boiler fuel oil systems, they are arranged so 

 that the diesel oil can be discharged to the fuel 

 oil service system and burned in the boiler fur- 

 nace in case of emergency. 



On aircraft carriers, JP-5 aviation fuel can 

 also be used as boiler fuel in case of emergency. 

 The JP-5 system is separate from the boiler 

 fuel oil system but can be connected so as to 

 discharge JP-5 to the fuel oil service system. 



DISTILLATE FUEL SYSTEM 



The Department of Defense has authorized 

 the Navy to convert to an all-distillate marine 

 type diesel fuel (Navy Special Distillate Fuel) 

 (NSDF) to replace the Navy Special Fuel Oil 

 (NSFO) now in use on steam-driven ships. 



Testing is now being conducted on gas tur- 

 bines and diesel engines for the feasibility of 

 converting the Navy to a "one fuel" Navy for 

 logistic simplicity and reduction of overall 

 operating costs. 



Piping system conversion and changes will 

 require the upgrading and validation of the 

 existing systems on all ships using NSFO. 

 Therefore, all instructions issued by NavShips 

 and NavSec shall be followed in upgrading and 

 validation of the existing NSFO systems before 

 NSDF can be introduced into the system. 



Stability and buoyancy will also be affected 

 due to the variation in specific gravity of NSFO 

 (7.9 lbs/gal average) verses NSDF (7.2 lbs/gal 

 average), therefore, solid ballast will be re- 

 quired in those ships which are now near the 

 naval architectural limits for stability. The 

 existing liquid loading instructions which specify 

 sea water ballasting of empty fuel tanks will 

 still remain in effect. 



MAIN LUBRICATING OIL SYSTEMS 



Main lubricating oil systems on steam- 

 driven ships provide lubrication for the turbine 

 bearings and the reduction gears. The main 

 lube oil system usually includes a filling and 

 transfer system, a purifying system, and 

 separate service systems for each propulsion 

 plant. On most ships, each lube oil service 

 system includes three positive-displacement 

 lube oil service pumps: (1) a shaft-driven pump, 

 (2) a turbine-driven pump, and (3) a motor- 

 driven pump. The shaft-driven pump, attached 

 to and driven by either the propulsion shaft or 

 the quill shaft of the reduction gear, is used 

 as the regular lube oil service pump when the 

 shaft is turning fast enough so that the pump 

 can supply the required lube oil pressure. The 

 turbine-driven pump is used while the ship is 

 getting underway and is then used as standby 



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