Ships and marine technology -- Lubricating oil systems -- Guidance for grades of cleanliness and flushing

ISO 28520:2009 provides guidance for flushing of lubricating oil systems, and grading of the resultant cleanliness. The flushing process is twofold: to remove dirt from the erection and installation, and to demonstrate that the pipes and the system as a whole is sufficiently clean. Crankcase and, where applicable, gearbox etc. are cleaned separately before flushing, and requirements relating to this are also specified in ISO 28520:2009. Similar considerations apply to the system tank and other components of the system. For the purposes of ISO 28520:2009, the cleaning process is considered as “washing through” when the Reynolds is equal to or less than 3 000 and “flushing” when the Reynolds number is equal to or greater than 3 000. Where available, any original equipment manufacturer requirements for flushing take precedence over the requirements outlined in ISO 28520:2009.

Navires et technologie maritime -- Circuits d'huile de graissage -- Guide relatif aux degrés de propreté et de rinçage

General Information

Status
Published
Publication Date
08-Feb-2009
Current Stage
6060 - International Standard published
Start Date
22-Jan-2009
Completion Date
09-Feb-2009
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INTERNATIONAL ISO
STANDARD 28520
First edition
2009-02-15
Ships and marine technology —
Lubricating oil systems — Guidance for
grades of cleanliness and flushing
Navires et technologie maritime — Circuits d'huile de graissage —
Guide relatif aux degrés de propreté et de rinçage
Reference number
ISO 28520:2009(E)
ISO 2009
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ISO 28520:2009(E)
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ii © ISO 2009 – All rights reserved
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ISO 28520:2009(E)
Contents Page

Foreword............................................................................................................................................................ iv

1 Scope ..................................................................................................................................................... 1

2 Normative references ........................................................................................................................... 1

3 Terms and definitions........................................................................................................................... 1

4 Recommended degrees of pipe cleaning........................................................................................... 2

4.1 Degrees of pipe cleaning during/after prefabrication....................................................................... 2

4.2 Inside surface treatment ...................................................................................................................... 2

5 Cleaning of system components ........................................................................................................ 2

5.1 Pumps, valves, filters, oil coolers, etc................................................................................................ 3

5.2 Engine crankcase ................................................................................................................................. 3

5.3 Gearbox ................................................................................................................................................. 3

5.4 Tanks...................................................................................................................................................... 6

5.5 Special comments ................................................................................................................................ 6

6 Flushing ................................................................................................................................................. 6

6.1 Flushing practice (2-stroke engine).................................................................................................... 6

6.2 4-stroke engines (practical execution) ............................................................................................. 12

6.3 Flushing execution ............................................................................................................................. 12

6.4 Flushing practice (turbines and turbo generators) ......................................................................... 13

7 Approval of flushing........................................................................................................................... 13

© ISO 2009 – All rights reserved iii
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ISO 28520:2009(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 28520 was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee

SC 3, Piping and machinery.
iv © ISO 2009 – All rights reserved
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INTERNATIONAL STANDARD ISO 28520:2009(E)
Ships and marine technology — Lubricating oil systems —
Guidance for grades of cleanliness and flushing
1 Scope

This International Standard provides guidance for flushing of lubricating oil systems, and grading of the

resultant cleanliness. The flushing process is twofold:
⎯ to remove dirt from the erection and installation, and
⎯ to demonstrate that the pipes and the system as a whole is sufficiently clean.

Crankcase and, where applicable, gearbox etc. are cleaned separately before flushing, and requirements

relating to this are also specified in this International Standard. Similar considerations apply to the system tank

and other components of the system.

For this International Standard, the cleaning process is considered as “washing through” when the Reynolds

number, R , is u 3 000, and “flushing” when the R W 3 000.
e e

NOTE If available, any original equipment manufacturer requirements for flushing take precedence over the

requirements outlined in this International Standard.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

ISO 4406, Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles

ISO 8501-1, Preparation of steel substrates before application of paints and related products — Visual

assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steel

substrates and of steel substrates after overall removal of previous coatings

ISO 28521 , Ships and marine technology — Hydraulic oil systems — Guidance for grades of cleanliness

and flushing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
1) To be published.
© ISO 2009 – All rights reserved 1
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ISO 28520:2009(E)
3.1
main engine
prime mover used for propulsion of the vessel or to drive a ship's generator
3.2
turbocharger

centrifugal blower driven by exhaust-gas turbines and used to supercharge an engine

3.3
lubricating oil

petroleum product designed to reduce friction and heat between moving parts in internal combustion engines

3.4
Reynolds number

dimensionless ratio of the internal flow forces to the viscous forces within a fluid

NOTE An indicator of the flow characteristics (laminar or turbulent) of a moving fluid.

4 Recommended degrees of pipe cleaning

This clause specifies the recommended degrees of pipe cleaning during and after prefabrication for pipes or

parts, possibly followed by inside surface treatment.

To ensure the best possible conditions for flushing, individual prefabricated parts should be made and

cleaned, before erection on-board.
4.1 Degrees of pipe cleaning during/after prefabrication

Concerning prefabrication of pipes and parts, it is recommended that these are completely cleaned inside,

which means that all welds associated with the welding of pipe sections and pipe branches should be smooth

and free of slag, welding spatter, burns and porosities. Fillet welds on flanges should be smooth and finely

grounded and should also be free of roundings as these can damage part of the joint faces. Concerning

possible subsequent chemical acid-cleaning or mechanical blast-cleaning, the degree of cleaning should

correspond to Sa 2 1/2 as specified in ISO 8501-1.

Steel sand should not be used for shot blasting, due to the risk of adhesion by magnetism or rusting; copper

(Cu) slag should be used instead. Sealing surfaces are to be mechanically well protected during shot blasting.

4.2 Inside surface treatment

In order to maintain the above-mentioned degree of cleaning before erection on-board, it is recommended that

the inside of the pipes be treated with an appropriate oil product.

Painting the inside with appropriate paint is sometimes prescribed by various manufacturers, and any such

requirements should be followed.
5 Cleaning of system components

Shot blasting, grinding, painting and welding should not be executed in the near vicinity during cleaning

operations on the items listed in 5.1 to 5.4.
2 © ISO 2009 – All rights reserved
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ISO 28520:2009(E)
5.1 Pumps, valves, filters, oil coolers, etc.
System oil requirements shall be requested from suppliers of these auxiliaries.
5.2 Engine crankcase

When engines (especially large engines) are delivered without cleaned and sealed lubricating oil systems,

including the crankcase, the crankcase shall be cleaned before flushing. This can be done as follows.

a) Blank-offs are placed on each oil drain to the engine mainframe. Starting at the top of one cylinder block

at a time, the inside of the crankcase is washed down with oil to remove rough particles. During this task

the engine crankshaft is turned at regular intervals so that chains, chain wheels, and the crankshaft are

washed down and cleaned.

b) A thin, non-drying oil, is recommended (about SAE 10 to 30 cSt), the remainder of which is compatible

with the system oil, which can dissolve the rust-prevention product which the engine has been coated

with when delivered. System oil (SAE 30 − 90 cSt or SAE 40 − 175 cSt) may be employed instead,

provided the oil is heated to 55 °C to 60 °C. In practice, 200 l to 400 l per cylinder have proven to be

sufficient, with the same quantity used for camshaft drive.

When the camshaft drive is cleaned, the thrust bearing cover is removed, if possible, and the thrust bearing is

washed down. Furthermore, the thrust-bearing ahead and astern thrust-pads are taken out for wiping if

possible. Ensure that the flash point of the oil is not too low (danger of fire).

Some rust prevention oils can influence the foam characteristic of the system oil; this occurrence can be

limited in the following way. The work can be partly done from the outside of the crank and shaft casting

through various inspection covers. After an appropriate amount of time, allowing for dripping and draining, the

dirty flush oil and deposited sediments shall be removed from the oil sump. The inside of the engine is then

wiped with lint-free and non-frayed cloths, and an inspection is made before the actual flushing is

commenced.
5.3 Gearbox

If gears are delivered with no cleaned and sealed lubrication oil systems, including pump and pipes, the gears

shall be cleaned before flushing.
5.3.1 Sealed gearboxes
For sealed gearboxes, external piping, filters and pumps, see 6.3.1.
5.3.2 Non-sealed gearboxes

For non-sealed gearboxes (when assembling gearboxes, including external pump, piping, filters and coolers)

see 6.3.2.
5.3.3 Choice of cleanliness level

The most impurity-sensitive components in a gearbox are, typically, ball- and roller-bearings. Information

concerning required bearing-cleanliness may be obtained from the bearing supplier, but shall in all cases be

stated by the gearbox supplier.

To a wide extent, the demand for life cycle and bearing load conditions shall guide the choice of cleanliness

level.

Bearing manufacturers have developed a bearing-lifetime theory, which among other items includes the

influence of impurities on service lifetime based on system lubrication oil. Figures 1 and 2 show the

relationship between size and hardness of impurities, how harmful they are to bearing life, and how important

it is to focus on cleanliness.
© ISO 2009 – All rights reserved 3
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ISO 28520:2009(E)
Key
X grain hardness, expressed in Vickers hardness (HV)
Y grain size, expressed in micrometres
Harmless.
Harmful.

NOTE In the calculation of these results the following parameters are used: friction coefficient, µ, 0,1; oil film

thickness 0,4 ∝m; hardness of outer track and roller 800 HV.

Figure 1 — Attrition particle's damaging effects with relation to their size and hardness

4 © ISO 2009 – All rights reserved
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ISO 28520:2009(E)
Key
L bearing lifetime, expressed in million revolutions
X absolute filter fineness, expressed in micrometres
Figure 2 — Bearing lifetime (L ) as a function of filter fineness

Table 1 indicates proposals for the degree of cleanliness for the various gear types.

Gear type, in this context, is a specification that combines and includes such characteristics as speed, load

variation and lifetime frequent start-stop.
Table 1 — Level of cleanliness for the various types of gear

Type of gear Level of cleanliness Level of cleanliness Max. allowable Typical service oil

after approved after commissioning contamination during filter
flushing trial service
ISO 4406 ISO 4406 ISO 4406
β > 75
1 16/14/11 17/15/12 18/16/13 3-5 µm
2 17/15/12 18/16/13 19/17/14 5-10 µm
3 18/16/13 19/17/14 20/18/15 5-10 µm
4 21/19/16 22/20/17 23/21/19 20-50 µm
The classification of type of gear (number) is explained as follows.

1) Demand for long service life, high operational reliability, high gear load, rpm (> 3 000), frequent start-stop,

such as on ferries with gas turbines on short crossings, and high loaded gear with mu

...

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