Bearings -Training Course 2002

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Bearings -Training course 2002

• Statistic's

• Recent service experience with standard thick shell main

bearings.

• Case story – L70MC/ Thin shell bearings/ Hydraulic trippel

jacks.

• New type measure equipment for journals and saddles.

• Cross head bearings – test with changed clearances, larger oil wedges and removal of the lead over layer.



Bearings Training course 2002

• Statistics.– Number of reported damages to MC engines.




• Statistics.– Number of reported damages to MC engines.Position in

relation to previous graph.




• Statistics.– Number of reported damages to MC engines.

Graphic presentation of the positive influence by

the OLS type main bearing, reduced top clearance

and off-set / alignment procedure updates.

Fore: Main bearing # 1 & 2

Aft: Three aft most main bearings

Centre: Remaining main bearings

Alignment

procedure finalised

Flex-edge

introduced.New SL – Reduced

Top clearances



Statistic:Reported main bearing damages S80-90MC-C.

The one reported

damage is believed to

be caused by a local

production mistake on

the bearing shell. The

damage was very small

and presumably caused

by a small hollow area

Percentage in relation to total number of main bearings in service = 0,89%




• Test of individual features – in this case ”flex edge”

The flex edge type were tested on a 8S60MC # 6 –

which had suffered 3 repeated damages – The

inspection after 6000 hours revealed good condition.




• ”Thick film” test main bearing – Features:

• Test of individual features – in this case ”flex edge”

The flex edge type were tested on a 8S60MC # 6 –

which had suffered 3 repeated damages – The

inspection after 2000 hours revealed good condition.



Bearings - Training course 2002

• ” Flex edge bearings in service”

A s ia n P ro gre ssLL 919140

8S 80MCMIT 3804

M B N o .: 6 01-09-27 S in gapore

MignonLL 918925

8S 60MCHan 98464

M B no 6 . 01-

MignonLL 918925

8S 60MCHan 98464

MB no 6 .O pe n-up in sp ec tion

01-05-11 Gothenburg

Mignon

LL 918925

8S 60MC

Han 98464

MB no 6 .

O pe n-up in sp ec tion02 .04 .16 B remerhaven

LuxembourgLL917143

7S 80MCHA N97434

M B no 4 and no 7 . 02-01-05 Fos sur M er

Sonangol K izombaLL 920377

6S 70MCKor H506

M B no 2 and 7 02-01-15PhiladelphiaDelaware

Iria TapiasLL921275

6S 70MCHS D 99514

M B N O 2. 02-01-24 A lg eciras

Sonangol Luanda

LL 920376

6S 70MC

Kor H

M B N o 7

M B N o 2

02-02-06

02-02-28

Gibral tar

Fos sur Mer A lb em arle Is la ndLL905960

8S 60MCMIT 3276

M B no 6 02 .03 .18 A ntwerpen

A rto isLL923096

7S 80MCH it

M B no 8 02 .04 .14 R otterdam

I ran Semna nLL 917145

6S 70MCHS D 97459

M B no 7 02 .05 .01 M alta



Bearings - Training course 2002• ” Flex edge bearings - Drawing ”



Bearings - Training course 2002• Reduced top clearances – Service experience.

Vessel

LL. No.

Eng.Type

Maker

Date Bearing

No

TC MIN

/acc SL

Damaged

againDonQuijote

8S60MC Juni 98 4 0,15(Belowmin)

No

Boheme917656

8S60MC99.08.22 7, 9 X No

ChannelAliance912746

6S70MC 99.01.08 1 X No

CharlesIsland905962

8S60MC 99.06.02 No. 6(NHNdesign)

X No Clipper HaraldLL917306

6L50MC 99.05.18 7 X No

Clipper VikingLL917305

6L50MC 99.09.13 4 lejer X No

Colombia917507

6S70MC 99.05.12 7 X No EagleAugustaLl 904651

6S60MC 99.07.12 5 X No

Heng Chan917465

6S70MC 99.12.30 3 X No Knock Ann

904105

6S70MC 98.11.19 4 X No




KotaHarmuni

6S50MC 99.03.30 X Fax Infod.00.02.10

from builder,problemsolved byreducing topclearance in# 1,2&3.

Luxemburg 77S80MC 99.07.03 6 X No MareInternum 8S70MC

MK599.05.15

4,6 X No

MareThracium

8S70MCMK5

99.05.284,6 X Backoil

No

Marethracium915152

8S70MC M6Hyu

99.08.066 X No

Mattea913188

2x7S50MCML 0049and 0050

99.11.08 5,7 X No

Mignon918925

8S60MCKOR 98464

99.11.20 1,6,7,9 X No (- 6)

Peene Ore914979

7S80MCKor 96362

99.01.19 7 X No Picardie917144

7S80MCKOR097435

99.10.17 4,7 X No




Tai Shan917464

6S70MCHYUAA1068

99.11.06 6,7 X No Asakasan915768 6S70MCHYU A0967 00.06.26 1 X No BritishProgress918015

7S80MC 00.10.22 5 X No

ChristianeOldendorff

Ll. 912309

5S50MC 00.01.24 5 X No

Eric LD916922

6S70MC 00-03-178 2 X No Frank A.Shrontz916483

7S80MC 00.09.23 5 X No

Heng Shan

917465

6S70MC 00.02 3,4,5 X No Isere918877

6S50MC 00.02.17 1,2 X No Manon917972

8S60MC 00.02.8-12 1,6,7,9 X No Seine 6S50MC Marts 00 2,5 X No

YükselGüler 916098

1 X No



Main bearings Training course 2002• Summery damage situation:

San

Francisco

Unit no when Where

# 2 damaged - replaced 2/10-01 USA

# 5,6 and 7(upper) found damaged, #5 and #7 replaced. 28/10-01 Melbourne

and Sydney

#6 Replaced 14/12-01 Melbourne

# 2 and # 5 – Repeated damage – Replaced.

# 4 found damaged and replaced

7-14/01-

02

USA



Main bearings Training course 2002• Summery damage situation:

Samaria Unit no when Where

# 2 and # 5 (damaged) 22/9-2001 Singapore

#6 Inspected – Condition OK 22/9-01 Singapore

#5 Inspected – Hair cracks – scraped re-installed. 12/10-01 La Spezia

#4 found damaged and replaced – Saddle/house geometry

measured.

5/11-01 Melbourne



Main bearings Training course 2002

• Findings – cause of damage: Small signs of light relative

movements suggesting that the

bearing house – not have been

fully ”compressed”. This is

supported by the loosening

pressure of 350-400 bar.




• Findings – cause of damage:Measurement of

bearing house

geometry by

means of strain

gauge based

bridge and

proximeters.




• Findings – cause of damage – Results of measurements :

Bearing cap dismounted

Bearing cap tightened 700 bar

Saddle in ”free” condition

Bearing house complete tightenedto 700 bar.



If the hydraulic jacks

are not fully

compressed beforestarting the

tightening sequence –

Interference between

the piston and the

body may occur.

The result will be as

in this case that only

the upper jack will

provide extension of

the stud, thus tension

of the bearing house.




• Conclusion - As per our Service report:

In- correct tightening of the bearing housings.

•The reason for this is believed to be hydraulic jacks not being fully

compressed prior to the start of the tightening sequence.

• The reason for not discovering the phenomenon should properly be found in

a consequently inadequate tightening with approx. 350-400 bars both during

machining of the bearing house and during assembly of the engine. This will

provide top clearances in accordance with the specified – but will result in a

inconsistent bearing housing geometry leading to a change in the ratio

between the top and side clearance.•Retightening to correct pressure/force will result in a decrease of the top

clearance as observed – but our investigations indicate that this change in

bearing house geometry may not have negative influence on the performance

of the bearings involved.





Main bearings – Repeated damages M/V San Francisco # 2 and #5 and

experienced damage in main bearing # 4 ( USA January 2002)

Main bearing No 2:

Inclined journal imprint – larger toward fore – Result”edge load toward fore”.







Main bearing No 2: Countermeasure.

Prior to the installation of the new lower shell in SanFrancisco the forward edge was relieved by manual

scraping to improve the situation – The inspection in

L.A revealed good condition. Light additional scraping

was made on the remaining line indicated by red arrow







Main bearing No 5 : Findings and countermeasure:

The new lower shell was similar to # 2 made with

corrective scraping on the forward edge

corresponding to the visual appearance on the

damaged bearing shell.







Main bearing No 4 : Findings and countermeasure:




Countermeasures introduced to avoid similar situations in the

future:

• Service Letter has been issued – in order to further highlight the

importance of a correct use of the hydraulic jacks.

• Quality Specification has been issued intended to be used at the

engine builders to prevent wrong tightening prior to the

machining of the bearing houses.

• New updated Quality specification regarding ” Rectification of

main bearing saddles MC/C engines” have been issued.




• Journal geometry – Verification :




• Cross head bearings – Test with changed ratio to the oil –

wedges.

Wiped lead into the oil wedges – in this case however

insignificant amount.




• Cross head bearings – Test oil –wedges.

Same unit as in the previous slide

– however oil-wedges enlarged

by hand scraping prior toinstallation.

Flattened wedges

2x standard length

– same depth




• Cross head bearings test with all features: Enlarged

clearances, oil wedges, missing lead over layer, larger centre pads:

L60MC

Sameengine

as

previous

photos.






L35MC – AlSn40 – CPP Propeller.

Bearings -Training Course 2002

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