SL2009-507.pdf

Service Letter SL09-507/HRR

Action code: WHEN CONVENIENT

Cylinder Lubrication Update

Guiding ACC Feed Rates for Alpha Lubri-

cator and ME Lube

Replaces SL07-479/HRR for large bore

engines

SL09-507/HRR

April 2009

Dear Sirs

Concerns

MAN B&W two-stroke 60-98 cm

large bore engines.

Types: MC/MC-C, ME/ME-C with high top-

land and Alpha Lubricator or ME Lube.

Based on experience and research, we have lowered our recom-

mended ACC (Adaptive Cylinder oil Control) feed rate factors for plants

equipped with Alpha Lubricator or ME Lube system. Consequently,

our previous recommendation, announced in SL07-479/HRR, issued

in June 2007, is only valid for engine types not covered by this service

letter.

Summary

New cylinder lubrication recommendation

0.20 g/kWh × S%.

Absolute minimum: 0.60 g/kWh.

We now recommend the following feed rates:

Standard BN70 lubricating oil

Fuel oil with sulphur content 3% and below 0.60 g/kWh

Fuel oil with sulphur content above 3%

0.20 g/kWh × sulphur%

This service letter speciﬁes the recommended ACC feed rates for dif-

ferent types of lubricating oil during during running-in, low-sulphur fuel

operation and standard engine operation.

A ready-to-print page, summarising feed rates for any lubrication situa-

tion is available on page 5, and selected ACC settings for BN70, BN50

and BN40 lubricating oils are listed on page 6.

Yours faithfully

Mikael C Jensen

Vice President, Engineering

Stig B Jakobsen

Senior Manager, Operation

New ACC guidelines further emphasise the

advantage of the Alpha Lubricator system

Head ofﬁce (& postal address)

MAN Diesel

Teglholmsgade 41

2450 Copenhagen SV

Denmark

Phone: +45 33 85 11 00

Fax: +45 33 85 10 30

mandiesel-cph@mandiesel.com

www.mandiesel.com

PrimeServ

Teglholmsgade 41

2450 Copenhagen SV

Denmark

Phone: +45 33 85 11 00

Fax: +45 33 85 10 49

PrimeServ-cph@mandiesel.com

Production

Teglholmsgade 35

2450 Copenhagen SV

Denmark

Phone: +45 33 85 11 00

Fax: +45 33 85 10 17

manufacturing-dk@mandiesel.com

Forwarding & Receiving

Teglholmsgade 35

2450 Copenhagen SV

Denmark

Phone: +45 33 85 11 00

Fax:

MAN Diesel

Branch of MAN Diesel SE, Germany

CVR No.: 31611792

Head ofﬁce: Teglholmsgade 41

2450 Copenhagen SV, Denmark

German Reg.No.: HRB 22056

Amtsgericht Augsburg

MAN Diesel – a member of the MAN Group

+45 33 85 10 16

Service Letter SL09-507/HRR

Contents

Cylinder lubrication page 2

Cylinder chemistry page 2

Standard operation page 2

Low-sulphur fuel operation page 3

Running-in operation

The target BN-value in the cylinder drain oil is around 15–20.

A more acidic environment than recommended will increase

the cold corrosion and, consequently, the wear on the cylin-

der liner.

page 3

Cylinder lubrication

Four factors determine the lubricating oil feed rate:

In a more alkaline cylinder environment, surplus alkaline ad-

ditives may accumulate as calcium deposits on the piston

top land, possibly leading to mechanical bore polish. Lack of

corrosive refreshment of the liner surface is another risk fac-

tor leading to chemical bore polish. Bore polish is one of the

reasons for the most feared cylinder condition problem, i.e.

scufﬁng.

- sulphur content in the fuel oil

- alkali content in the cylinder lube oil

- engine history

- engine load.

Standard operation

We continuously perform lubrication feed rate tests on the

different MAN B&W engines types, under varying running

conditions and with varying fuel oil sulphur contents.

An Alpha Lubricator or ME Lube operating in ACC-mode

(Adaptive Cylinder oil Control) adapts the lubricating oil feed

rate to the fuel oil sulphur content and the engine load. The

ACC-mode has been the standard on MAN B&W two-stroke

engines since 2004.

Our most recent research shows that the optimum lubrica-

tion feed rate is lower than our previous recommendations.

The ACC factor is the determining factor in the feed rate

equation: Feed rate = ACC factor × sulphur%. The recom-

mended ACC factor is based on practical experiments

performed on different types of engines under varying run-

ning conditions. When determining the recommended ACC

factor, we consider engine performance, engine service life,

environment and economy.

New recommendations for standard operation with standard

BN70 lubricating oil:

BN70 lubricating oil

Fuel oil with sulphur content 3% and below

0.60 g/kWh

Fuel oil with sulphur content above 3%

0.20 g/kWh × S%

This service letter describes the cylinder feed rates in the

following operation situations:

Low-sulphur fuel oils call for less alkaline lubricating oil (see

page 3). Below is given the recommendations for selected

types of less alkaline lubricating oils:

-standard

- low-sulphur fuel

- running-in.

BN60 lubricating oil

Fuel oil with sulphur content 2.6% and below 0.60 g/kWh

Cylinder chemistry

The combustion process turns sulphur in the fuel oil into sul-

phuric acid. The higher the sulphur content in the fuel oil, the

more sulphuric acid is created.

Fuel oil with sulphur content above 2.6%

0.23 g/kWh × S%

BN50 lubricating oil

Fuel oil with sulphur content 2.1% and below 0.60 g/kWh

The alkaline content in the lubricating oil adds base to the

chemical environment in the cylinder. The base in the lubri-

cating oil will neutralise the sulphuric acid developed from

the fuel sulphur.

Fuel oil with sulphur content above 2.1%

0.28 g/kWh × S%

BN40 lubricating oil

Fuel oil with sulphur content 1.7% and below 0.60 g/kWh

The more base available, the more sulphuric acid can be

neutralised. This is why lubricating oil with a high level of al-

kaline additives, i.e. high-BN (base number) oil, is particularly

advantageous when operating on high-sulphur fuels.

Fuel oil with sulphur content above 1.7%

0.35 g/kWh × S%

Cylinder Lubrication Update. Page 2 of 6 pages

Service Letter SL09-507/HRR

ACC Cylinder Lubrication

Running-in operation

A MAN B&W two-stroke engine requires extra attention and

extra lubricating oil during its ﬁrst 2,500 running hours, the

ﬁrst 500 hours being the most demanding period.

!BSOLUTE

DOSAGESæ

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We classify the running-in period in three categories:

1. breaking-in (0-500 hours)

2. running-in, phase 1 (500-1,500 hours)

3. running-in, phase 2 (1,500-2,500 hours).

3ULPHURæ

The purpose of extra lubricating oil during the running-in

period is to:

- help ﬂush away wear particles

- build up oil ﬁlm in a not yet run in cylinder.

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THEæFUELæOILæSULPHURæCONTENTæFORæSELECTEDæLUBRICATINGæOILSæ".".

The running-in process has been eased and shortened con-

siderably by our alu-bronze running-in coating on all 4 piston

rings (standard on all MAN B&W two-stroke engines). Cylin-

der liner run-in is facilitated by our semi-honed liner surface.

Based on calculations of the average worldwide sulphur

content used on MAN B&W two-stroke engines, the average

cylinder oil consumption will be less than 0.65 g/kWh when

these new recommendations become effective.

Low-sulphur fuel operation

Low-sulphur fuel oil is necessary when operating in sulphur

emission control areas (SECA).

We recommend frequent scavenge air port inspections dur-

ing the ﬁrst 2,500 running hours (see Fig. 2).

Breaking-in (0-500 hours)

Piston ring and liner breaking-in takes 500 running hours,

maximum. We recommend a ﬁxed, relatively high lubrication

feed rate during the breaking-in period.

Operation on fuel oil with around 1.5% sulphur should pref-

erably be done in combination with a low-BN cylinder oil.

However, continuing on BN70 cylinder oil is possible for a

limited period of 7-14 days without any serious risks of over-

alkalinity.

During breaking-in, the running-in coating on the piston rings

will gradually wear off, and the wave shape of the cylinder

liner surface will smoothen. During this process, extra lubri-

cating oil is required to ﬂush away wear particles and build

a satisfactory oil ﬁlm between the still relatively rough sliding

surfaces.

We recommend using a lower-BN cylinder oil, when operat-

ing on low-sulphur fuels for extended periods (more than

14 days).

BN and low-sulphur fuel

MAN Diesel recommends a minimum oil feed rate of 0.60

g/kWh for any lubricating oil for hydrodynamic purposes.

During breaking-in, we recommend checking the piston

rings and the cylinder liner through the scavenge air ports

every 100 hours. Do not proceed to the next lubrication step

if the scavenge air port inspection reveals seizures or other

irregularities!

However, to avoid surplus alkaline additives in the cylinder,

we generally recommend that the alkaline content in the

lubricating oil match the sulphur content in the fuel oil. This

is particularly crucial when operating on low-sulphur fuel for

extended periods (more than 14 days).

Breaking-in

Feed rate, BN70 lubricating oil

0 - 5 hours

1.70 g/kWh

5 - 100 hours

1.50 g/kWh

100 - 200 hours

1.30 g/kWh

Low-BN oils should be chosen for low-sulphur fuels, and

high-BN oils for high-sulphur fuels.

200 - 300 hours

1.10 g/kWh

300 - 400 hours

0.90 g/kWh

Sulphur

400 - 500 hours

0.70 g/kWh

40 - 50

< 3.5%

60 - 70

> 2.5%

Cylinder Lubrication Update. Page 3 of 6 pages

Service Letter SL09-507/HRR

To avoid a high torque during breaking-in, we recommend

a 16-hours stepwise load increase from 50% load to max.

load.

When running in new piston rings in well running liners, we

recommend a 5-hour load-up from 50% load to max. load.

This load limitation can be set for a single cylinder unit by

adjusting the individual fuel pump index.

Running-in, phase 1 (500-1,500 hours)

After the ﬁrst 500 running hours, standard sulphur-depen-

dent lubrication can be applied. Hence, ACC can take over

lubrication.

For a BN70 oil, MAN Diesel recommends a running-in,

phase 1 dosage of 0.26 g/kWh x sulphur %.

Running-in, phase 1

Feed rate, BN70 lubricating oil

500 - 1,500 hours

0.26 g/kWh × S%

Running-in, phase 2 (1,500-2,500 hours)

After 1,500 hours, the running-in piston ring alu-coating is

usually worn through, and the base material or the cermet

coating on the top and bottom rings is visible.

When reaching 1,500 running hours, carefully check the

piston rings and the cylinder liner through the scavenge air

ports. If the alu-coating is worn through, proceed to running-

in, phase 2.

For a BN70 oil, MAN Diesel recommends a running-in, phase

2 dosage of 0.23 g/kWh × sulphur %.

Running-in, phase 2

Feed rate, BN70 lubricating oil

1,500 - 2,500 hours

0.23 g/kWh × S%

Inspect the piston rings and the cylinder liner through the

scavenge air ports after 2,500 running hours. If no micro

seizures or other irregularities are found, we recommend

switching to the standard operation feed rate of 0.20 g/kWh

× sulphur%.

Cylinder Lubrication Update. Page 4 of 6 pages

Service Letter SL09-507/HRR

Table l: Guiding Cylinder Oil Feed Rates for all Operation Situations

MC/MC-C, ME/ME-C and ME-B engines with high topland and Alpha Lubricator or ME Lube

Standard BN70 cylinder oil BN60 cylinder oil

BN50 cylinder oil

BN40 cylinder oil

Basic setting

0.20 g/kWh × S%

0.23 g/kWh × S%

0.28 g/kWh × S%

0.35 g/kWh × S%

Minimum feed rate

0.60 g/kWh

Maximum feed rate during running-in

1.7 g/kWh

Part-load control

100% to 25% load: proportional to indicated engine load

25% load and lower: proportional to rpm

Running-in new or reconditioned

liners and new piston rings based

on standard BN70 cylinder oil

Feed rate

First 5 hours

1.7 g/kWh

5 - 500 hours:

stepwise reduction from 1.5 to 0.6 g/kWh

500 - 1,500 hours:

0.26 g/kWh × S% (absolute min. 0.60 g/kWh)

1,500 - 2,500 hours:

0.23 g/kWh × S% (absolute min. 0.60 g/kWh)

From 2,500 hours:

0.20 g/kWh × S% (absolute min. 0.60 g/kWh)

Engine load Testbed:

stepwise increase to max. load over 5 hours

In service:

from 50% to max. load over 16 hours

Running-in new rings in already run-in and well

running liners (standard BN70 cylinder oil)

From 50% to max. load in 5 hours

Feed rate: +25% for 24 hours

Manoeuvring and load change situations

During starting, manoeuvring and load changes, increase feed rate by means of the “LCD” by

25% of the actual ﬁgure. Keep this level for ½ hour after the load has stabilised.

Lubrication of cylinders that show abnormal

conditions

Frequent scavenge air port inspections of piston rings and cylinder liners are very important

for maintaining a safe cylinder condition. If irregularities are observed, consider adjustments

of the lube oil rate.

In case of scufﬁng, sticking piston rings or high liner temperature ﬂuctuations, raise the feed

rate to 1.2 g/kWh and lower p max and mep. As soon as the situation has been stabilised, set

the lubrication feed rate and the pressures back to normal.

ACC Running-in Schedule

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Cylinder Lubrication Update. Page 5 of 6 pages

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