Maintenance
Proper maintenance is an important, but often overlooked operating parame-
ter that is difficult to quantify. If the bowl is not cleaned in time, deposits will
form on the bowl discs, the free channel height will be reduced, and flow
velocity increases. This further tends to drag particles with the liquid flow
towards the bowl’s centre resulting in decreased separation efficiency.
Check of lubricating oil system
For cleaning of the lubricating oil system after overhauls and inspection of the
lubricating oil piping system the following checks must be carried out:
1. Examine the piping system for leaks.
2. Retighten all bolts and nuts in the piping system.
3. Move all valves and cocks in the piping system. Lubricate valve spindles
with graphite or similar.
4. Blow through drain pipes.
5. Check flexible connections for leaks and damages.
6. Check manometers and thermometers for possible damages.
7. Engines running at HFO, will as standard be delivered with centrifugal
by-pass filter mounted on engine. Centrifugal by-pass filter can be used
as indicator of lubricating oil system condition.
Define a cleaning interval (ex. 100 hours). Check the sludge weight. If
the sludge weight is raising please check separator and lubricating oil
system condition in general.
Deterioration of oil
Oil seldomly loses its ability to lubricate, i.e. to form a friction-decreasing oil
film, but it may become corrosive to the steel journals of the bearings in such
a way that the surface of these journals becomes too rough and wipes the
bearing surface.
In that case the bearings must be renewed, and the journals must also be
polished. The corrosiveness of the lubricating oil is either due to far advanced
oxidation of the oil itself (TAN) or to the presence of inorganic acids (SAN). In
both cases the presence of water will multiply the effect, especially sea water
as the chloride ions act as an inorganic acid.
Signs of deterioration
If circulating oil of inferior quality is used and the oxidative influence becomes
grave, prompt action is necessary as the last stages in the deterioration will
develop surprisingly quickly, within one or two weeks. Even if this seldomly
happens, it is wise to be acquainted with the signs of deterioration.
These may be some or all of the following:
â–ª Sludge precipitation in the separator unit multiplies
â–ª Smell of oil becomes acrid or pungent
â–ª Machined surfaces in the crankcase become coffee-brown with a thin
layer of lacquer
â–ª Paint in the crankcase peels off or blisters
â–ª Excessive carbon is formed in the piston cooling chamber
Description
Treatment and maintenance of lubricating oil
1643494-3.11
2016-02-26 - en
B 12 15 0
MAN Diesel & Turbo
10 (11)
L28/32S; L27/38S; L23/30S; L21/31S; L16/24S; L23/30DF; V28/32S-DF;
L28/32DF; V28/32H; V28/32S; L16/24; L21/31; L23/30H; L27/38;
L28/32H EN
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