Machinery Lubrication May June 2014 May June 2014 | Page 14

component manufacturer. However,
the dangerous size normally is smaller
than the human eye can see (less than
40 microns). In practice, a machine
consists of many components (e.g.,
bearings, sealing glands, hydraulics,
etc.), so the purity of the oil and the
system should meet the requirements of
the most demanding component. In a
typical

turbine

system,

hydraulics

require the highest oil cleanliness and
the smallest average size of dangerous
particles.

Is Flushing Always Enough?
Most

available

recommendations

standards,
and

industry

practices place a lot of attention on the

Magnetic ferrous particles attached to magnets from an oil system

operation, these impurities are carried

pipelines, coolers, tanks and other

flushing process before startup of the

by oil to lubricated components,

elements.

system. While turbulent flushing of

depositing on the inner walls of

dangerous-sized

contaminants

will

The presence of water accelerates the

prepare an oil system for safe operation,

creation of corrosion inside the system.

only a well-designed flushing procedure

The current trend is to build oil systems

will be effective. In many cases, even the

Hydrodynamic cleaning and flushing
of oil systems is quickly becoming a
preferred choice of OEMs and maintenance/repair companies. Since 1994,
more than 450 different turbine oil
systems have been serviced with this
technology, including newly commissioned and refurbished machinery
ranging from:

from stainless steel. However, some

most turbulent flows will not remove

parts

rapidly

well-attached/sticky deposits from the

(armature, tanks, etc.) may still be

system walls. When flushing a system in

made of carbon steel. In older systems,

which such deposits are present,

which are made mostly of carbon steel,

reaching the required oil cleanliness can

the problem of corrosion is significant.

be

These systems are prone to corrode

reasonable oil cleanliness can take a

• Turbo-generators (steam and
gas turbines)

quickly, especially in parts that are not

long time.

• Process
turbo-compressors
and blowers (hydrocarbons,
synthesis gas, hydrogen, air,
ammonia, etc.)

return lines, tank roofs, etc.), due to

In addition, during initial startup and

water condensation on these surfaces.

regular operation of a turbine when

Practical Applications

• Boiler feed pumps with
hydrokinetic couplings and
gearboxes
• Large industrial diesel engines
(including auxiliary power
supply in nuclear power plants)
• Large marine diesel engines

that

can

corrode

difficult.

Indeed,

achieving

permanently filled with oil (gravity

conditions are quite different than
With oil such a key component of any

when flushing (system vibrations from

mechanical device, problems related to

machinery, high temperatures, different

the lubricant often turn into problems

flow velocities, shocks from pump

with the machinery. In most cases,

starts, valves opening, etc.), it is

impurities in the oil mean interruptions

common for new particles to detach

in machinery operation.

from remaining (after flushing) dirt
from the system walls. Diminishing oil

• Large hydraulic and lubricating oil systems in steelworks
and rolling mills

Particles in the oil that can be damaging

cleanliness is then usually observed.

to lubricated components may be very

This type of situation is most often

• Central lube oil distribution
systems in plants

different in size, depending on the

visible when severe deposits are present

cleanliness requirements given by the

in the system, especially varnish, sludge

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