Main Lube Oil System The primary function of the Lube Oil system is to supply lubricating oil at the proper pressure and temperature temperature to the main propulsion turbines and reduction gears. The lube oil not only lubricates the machinery, but it also cools and helps reduce reduce rustin rusting. g. Secon Seconda dary ry funct functio ions ns includ includee purif purifyi ying ng oil oil that that has has becom becomee contaminted and transferring oil to or from the sump tank, gravity tank, storage tank, settling tank, sludge tank, or deck connections. The lube oil service system is provided with two lube oil service pumps. One vertical rotary, motor driven and one reciprocating pump connected so that one unit is available for standby operation while the other unit is supplying supplying the system. The lube oil service pump has a capacity of 43 gpm and lube oil standby 4! gpm, at a discharge discharge pressure of ". psig, and one pump by itself is capable of supplying the entire oil re#uirements of the main propulsion unit under any power conditions. The lube oil system is provided with two coolers, either of which is capable of handling the full re#uirements of the system with the other on standby. These coolers are of the single pass, shell and tube type capable of cooling 43 gpm of oil, with a viscosity of !! SS$ at %!!& '., when supplied with 4"! gpm of sea water at (& '. )ote that oil pressure is greater than sea water pressure. The coolers are mounted in parallel and the piping arranged arranged so that either unit may be by*passed. There There is a drain connection connection from each cooler to a common common drain line terminating terminating in the main sump tank. + pound steam connection is provided in the inlet head of each cooler to allow for the warming of the oil, if necessary, prior to starting up the main propulsion unit. Steam for this purpose is supplied via a temporary hose from the auiliary ehaust and bleeder steam system. Storage tanks are of welded steel construction and large enough to hold at least one complete change of oil for the entire system. One storage tank of 3-!! gallon capacity may be filled from the service pump discharge or the deck connections. The tank, which contains only clean oil, may also be filled with oil from the purifier discharge. discharge. The tank is e#uipped e#uipped with a vent vent to the atmosphere, atmosphere, a pneumatic pneumatic type level indicator, a sound tube, and an overflow line which discharges to the main sump tank via an open funneled line. + 3-!! gallon settling tank is installed as part of the lube oil system. The tank is of welded steel construction and has enough capacity to hold all the oil from the entire system. The bottom is sloped to facilitate drainage to the purifier and sludge tank, with a high drain connection to the main lubricating system. The steam coils are fitted to heat the oil for settling purposes. The tank is normally used when settling oil during batch purification. purification. The tank is provided with thermometer, thermometer, vent,
pneumatic type level indicator as well as a sounding tube, heating coils, and an overflow line which discharges to the main sump tank via an open funneled line. The %(!! gallon gravity tank is also of welded steel construction and located in the engine room at sufficient heights to maintain %! psi oil pressure at the highest bearing. The gravity tank must carry at least three minutes supply of oil below the overflow pipe connection, when the machinery is operating at maimum continuous power. This reserve oil is to allow time to stop the shaft in the event that the lube oil pumps fail. The overflow pipe connection is located at a height e#ual to 34 the tank capacity. The tank is fitted with a suitable alarm to give warning of low oil supply. The tank is e#uipped with a vent, a pneumatic type level indicator as well as a sounding tube, low level alarm, and a continuous overflow drain to the main sump tank. The continuous overflow to the sump is discharged through an illuminated sight flow fitting, called a bulls eye, visible from the operating platform. The main sump is built into the ship/s structure and is located below the reduction gear casing. The tank is of sufficient si0e to hold all the oil from the gravity tank plus the oil in the system. The normal working capacity of the sump tank is %3-4 gallons, with a maimum capacity of approimately 3-!! gallons. The tank of steel construction, is fitted with baffles to prevent ecessive sloshing of the oil. This could result in emulsification of the oil. Oil from the gears drains directly to the sump1 and oil from the turbine bearings is collected and drained to the sump tank at a point remote from the service pump suction connection. The lube oil piping may be divided into two systems2 first, the service system including lube oil to the turbine, gears and governor1 and second, the purifying and storage system.
