Bearing Assessment for Wartsila 20

lmbo^qfkd fkpqor`qflk Service, Wärtsilä Finland Oy

Käyttöohje

Driftsinstruktion

Engine section

Engine type

Ref.

Date

Issue

10, 11 & 14

W20

WFI–S

12.03.2004 01

Document No.

Page

2010Q003GB

1(9)

Bearing assessment for WÄRTSILÄ® 20 General

The purpose of these instructions is to define assessment criteria for the sliding bearings of the WÄRTSILÄâ 20 engines (including small end bearings, big end bearings, main bearings and camshaft bearings). See the engine manual for further information: - Maintenance schedule (chapter 4) - Clearances and wear limits (chapter 6) - Bearing assembly instructions (chapters 10 and 11).

Bearing types

Possible bearing types of the engine are shown in figure 1. The type of the bearing has an influence on the visual wear pattern.

Figure 1. Bearing types. Inspection intervals

Bearings are to be inspected according to the maintenance schedule. See chapter 4 in the Engine Instruction Manual. Bearings are formed to the housing and unnecessary bearing dismantling should be avoided.

Wärtsilä Finland Oy Service, Vaasa

P.O. Box 252 (Tarhaajantie 2) FIN-65101 Vaasa, Finland

Telecop. +358 10 709 7355 Telecop. +358 6 356 7339

Tel. +358 10 709 0000

Wärtsilä Finland Oy Service, Turku

P.O. Box 50 (Stålarminkatu 45) FIN-20811 Turku, Finland

Telecop. +358 10 709 3279 Telecop. +358 10 709 3410

Tel. +358 10 709 0000

Business ID 0773744-3 Registered Office: Vaasa

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Document No. 2010Q003GB

Page 2(9)

Bearing lifetime

Bearing lifetime will be influenced by: - Engine load profile and operating conditions - Fuel and lube oil properties - Adequate prelubrication before starting and sufficient lubrication during operation - Proper oil maintenance including regular and optimized separation routines - Proper maintenance of lube oil filters - Clean working conditions while working inside the engine - Regular draining and cleaning of lube oil tanks

Bearing designations

It is recommended that new bearings are marked with an electrical engraving pen, see also chapter 00 of the instruction manual. The big end bearing should be marked with the cylinder number (figure 2) and the main bearing should be marked with the bearing number (figure 3).

Figure 2. Cylinder numbers.

Safety check

Figure 3. Bearing numbers.

After fitting a bearing, the bearing temperatures has to be checked and confirmed to be even between corresponding bearings: - Run the engine for about 5 minutes up to nominal speed with no load. - Follow the engine behaviour. - Stop and check the bearing temperatures by hand or with a temperature measuring device.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Document No. 2010Q003GB

Page 3(9)

Main bearing and big end bearing Bearing type Big end bearings and main bearings are bimetal type bearings. See fig. 1. Wear pattern The typical wear pattern of bimetal sliding bearings is a slight polishing over a broad arc on the most loaded area. Measurement of bearing shell A ball anvil micrometer should be used to measure bearing shell thickness. Measure the thickness on a few points on both sides (A and C) and the centre line (B) of the bearing as shown in figure 4. Free spread of the bearing is shown in figure 5. The free spread of the bearing has to be bigger than the inner diameter of the bearing housing. See Measurement record 2010V005GB for main bearing and 2011V006GB for big end bearing.

Figures 4. Measuring points on the bearing shell.

Figure 5. Free spread of the bearing shell.

Replacement guidelines for bearing shells It is recommended that the bearing is replaced if one of the below mentioned criteria is fulfilled: 1. Thickness of the bearing is under the wear limit. 2. Fretting on the back of the bearing. 3. Fatigue marks on the sliding surface. 4. Cavitation has penetrated through the bearing layer (minor cavitation is allowed). 5. Rough sliding surface: More than a few scratches or cavitation has worn the bearing on a wide area. 6. Corrosion on the bearing. 7. Recommended replacement interval of the bearing has been reached. Notes: - In case of doubt of the bearing condition, the bearing should be replaced to avoid consequential damage. - If there are scratches on the journal, it should be polished.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Small end bearing

Document No. 2010Q003GB

Page 4(9)

Bearing type Small end bearings are trimetal bearings with flash layer or solid bronze bearing bushes. See figure 1. Wear pattern Typical wear pattern of the small end bearings is two parabolas closing to each other in the middle of the bearing on the most loaded side. In trimetal bearings the wear pattern is more visible. See wear patterns in figures 6 and 7.

Figure 6. Trimetal bearing.

Figure 7. Solid bronze.

Replacement of small end bearing Small end bearings can be used until the wear limit has been reached. The small end bearing to be measured as shown in figure 8. Inner diameter should be measured in 4 directions (numbers 1-4) on both edges (A and B) by using a dial gauge. See Measurement record 2011V007GB.

Figure 8: Measuring points of the small end bearing.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Camshaft bearing

Document No. 2010Q003GB

Page 5(9)

Bearing type Camshaft bearings are bimetal or solid bronze bearing bushes and thrust bearing solid bronze bearing bushes. See figure 1. Wear pattern Typical wear pattern of the camshaft bearing is slight polishing on the loaded side of the bearing bush. Replacement of camshaft bearing Camshaft bearings are recommended to be replaced according to the maintenance schedule. A bearing bush is to be measured in the housing. As shown in figure 9, the inner diameter of the bearing bush should be measured in 4 directions (numbers 1-4) on both edges (D and E) by using a dial gauge. See Measurement record 2014V008GB.

Figure 9. Measuring points of bearing bush. Damage types

Some typical sliding bearing damage is described below: Smearing, wiping Smearing and wiping is bearing damage related to adhesion. This occurs if there is metal-to-metal contact due to failed oil film. Possible reasons are: - inadequate lubrication (e.g. starting without pre-lubrication) - low viscosity of lube oil - high bearing load - small clearances (e.g. inadequate fitting of bearing housing) Bearings as shown in figure 10 are to be replaced, because this kind of damage might lead to fatigue.

Figure 10. Wiping damage.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Document No. 2010Q003GB

Page 6(9)

Cavitation Cavitation is a phenomenon related to vaporisation pressure of the lube oil. Cavitation bubbles are formed when lube oil pressure decreases below the vaporisation pressure. When the local pressure rises above the vaporisation pressure, the bubbles will collapse and cause erosion wear of the material. Cavitation phenomenon is influenced by: - Big clearance - Incorrect lube oil pressure - Vaporisation pressure of the lube oil has decreased (for instance water/air in the oil, high oil temperature or dirty oil). Bearings as shown in figure 11 are to be replaced.

Figure 11. Cavitation damages. Fatigue Fatigue in the bearing surface layer begins with micro cracks, which are hardly visible without a microscope. These cracks will grow until the bearing layer starts to peel off in small flakes. Fatigue is influenced by: - Low viscosity of lube oil - Bearing overload - Improper bearing clearance - High lube oil temperature Fatigue on the bearing develops rather fast and will likely lead to bearing failure. The bearings are to be replaced whenever fatigue marks are visible. Fatigue damage is shown in figure 12.

Figure 12. Fatigue damage.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Document No. 2010Q003GB

Page 7(9)

Solid particles If solid particles are bigger than the oil film thickness, they will scratch the sliding surfaces or get embedded in the overlay material. See figure 13. The origin of solid particles could be: - Dirt from overhauling - Particles passing the filtrations - Particles from the combustion process - Wear particles from engine Note: Proper filtration is essential for lube oil cleanliness

Figure 13. Embedded particle (magnification 10x).

Corrosion Corrosion is the result whenever chemical reaction with the environment predominates. For example, an aluminium sliding surface is sensitive to water and cooling water additives. A bearing exposed to corrosion is to be replaced.

Figure 14. Corrosion damage.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Document No. 2010Q003GB

Page 8(9)

Fretting Fretting might occur on the back of the bearing if there is micro movement between the housing and the bearing. Possible reasons for fretting: - Low tightening torque of the screws - Low surface roughness - Improper assembly of the bearing - Reassembling of bearing with too low free spread - Dirt between the bearing and the housing Note: If fretting occurs, the bearing housing has to be dressed up before mounting a new bearing.

Figure 15. Fretting damage on the back of the bearing.

Misalignment and shape errors Misalignment and shape error wear pattern (polishing) on the bearing might occur due to following reasons: - Journal shape error - Shaft misalignment - Housing shape error If this kind of wear pattern occurs, the reason should be investigated and corrected if necessary.

Figure 16. Polished side edges.

Service, Wärtsilä Finland Oy

Operating instruction Issue 01

Document No. 2010Q003GB

Page 9(9)

Bearing assembly related problems If the bearing is not properly assembled in the housing, the bearing might be damaged (polishing, fatigue, wiping, etc.). Most of the assembly errors are caused by: - Incorrect mounting (for instance big end bearing shells grip each other during assembly) - Remaining dirt and/or black staining (oil carbon deposit) on the housing and the bearing back surfaces - Locating lug is not properly in its place Usually this kind of error can also be identified by the contact pattern on the back of the bearing.

Figure 17. Fatigue damage around the locating lug. Warranty

Unless otherwise expressly set forth, no recommendation contained in this document is to be construed as provided due to a defect in the engine, but merely as an improvement of the engine and/or the maintenance procedures relating thereto. Any actions by the owner/operator as a result of the recommendations are not covered under any warranty provided by Wärtsilä and such actions will thus be at the owners/operators own cost and expense.

Letter distribution

â Wärtsilä Service Network and owners/operators of WÄRTSILÄ 20 engines.

Letter validity

Until further notice.

Enclosures

Measurement records 2010V005, 2011V006, 2011V007 and 2014V008.

 2004 Wärtsilä Finland Oy – All rights reserved No Part of this publication may be reproduced or copied in any form or by any means (electronic, mechanical, graphic, photocopying, recording, taping or other information retrieval systems) without the prior written permission of the copyright holder. Wärtsilä Finland Oy makes no representation, warranty (express or implied) in this publication and assumes no responsibility for the correctness, errors or omissions for information contained herein. Information in this publication is subject to change without notice. NO LIABILITY WHETHER DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL, IS ASSUMED WITH RESPECT TO THE INFORMATION CONTAINED HEREIN. THIS PUBLICATION IS CONFIDENTIAL AND INTENDED FOR INFORMATION PURPOSES ONLY.

jb^probjbkq ob`loa Service, Wärtsilä Finland Oy Engine section

Engine type

Ref.

Date

10 Engine block

20

WFI–S

12.03.2004 01

Installation name: Fuel viscosity (cSt):

Issue

Engine type: Ambient temperature:

Main bearing shell (lower)

Document No.

Page

2010V005GB

1(1)

Engine No: Engine running hours:

Measuring points

Bearing shell ID: Big end bearing nominal thickness Big end bearing wear limit

= 7,405-7,420 mm = 7,36 mm

Measure with a ball anvil micrometer. Note: Pay attention not to press the measuring head in the running layer.

1

2

3

4

Bearing number 5 6

7

8

9

10

9

10

A1 A2 A3 A4 B1 Bearing B2 thickness (deviation in B3 1/100 mm) B4 C1 C2 C3 C4 Component running hours: Remarks/ Manufact. No:

Crankshaft

(journal)

Measuring points

Shaft designations: Bearing journal nominal diameter Bearing journal diameter, wear limit Bearing journal out of circularity, nominal Bearing journal out of circularity, wear limit Bearing journal taper, nominal

= 209,971-210,000 mm = 209,900 mm = 0,015 mm = 0,05 mm = 0,02/100

The diameter to be measured in 4 directions, fill in the min and max measure in the table.

1

2

3

4

Bearing number 5 6

7

8

D min D max Journal E min diameter (deviation in E max 1/100 mm) F max F max Component running hours: Remarks/ Manufact. No: Date of measurement:

Place:

Name:

Wärtsilä Finland Oy Service, Vaasa

P.O. Box 252 (Tarhaajantie 2) FIN-65101 Vaasa, Finland

Telecop. +358 10 709 7355 Telecop. +358 6 356 7339

Tel. +358 10 709 0000

Wärtsilä Finland Oy Service, Turku

P.O. Box 50 (Stålarminkatu 45) FIN-20811 Turku, Finland

Telecop. +358 10 709 3279 Telecop. +358 10 709 3410

Tel. +358 10 709 0000

Business ID 0773744-3 Registered Office: Vaasa

jb^probjbkq ob`loa Service, Wärtsilä Finland Oy Engine section

Engine type

Ref.

Date

11 Crank Mechanism

20

WFI–S

12.03.2004 01

Installation name: Fuel viscosity (cSt):

Issue

Engine type: Ambient temperature:

Big end bearing shell

Document No.

Page

2011V006GB

1(1)

Engine No: Engine running hours:

Measuring points

Bearing shell ID: Big end bearing nominal thickness Big end bearing wear limit

= 4,930-4,950 mm = 4,900 mm

Measure with a ball anvil micrometer. Note: Pay attention not to press the measuring head in the running layer.

1

2

3

4

Cylinder number 5 6

7

8

9

7

8

9

A1 A2 A3 A4 Bearing shell B1 B2 thickness (deviation in B3 1/100 mm) B4 C1 C2 C3 C4 Component running hours: Remarks/ Manufact. No:

Crankshaft pin

Measuring points

Shaft designation: Crank pin nominal diameter Crank pin diameter, wear limit Crank pin out of circularity, nominal Crank pin out of circularity, wear limit Crank pin taper, nominal

= 179,975-180,000 mm = 179,900 mm = 0,015 mm = 0,05 mm = 0,03/100

The diameter to be measured in 4 directions, fill in the min and max measure in the table.

1

2

3

4

Cylinder number 5 6

D min D max Pin diameter E min (deviation in E max 1/100 mm) F max F max Component running hours: Remarks/ Manufact. No: Date of measurement:

Place:

Name:

Wärtsilä Finland Oy Service, Vaasa

P.O. Box 252 (Tarhaajantie 2) FIN-65101 Vaasa, Finland

Telecop. +358 10 709 7355 Telecop. +358 6 356 7339

Tel. +358 10 709 0000

Wärtsilä Finland Oy Service, Turku

P.O. Box 50 (Stålarminkatu 45) FIN-20811 Turku, Finland

Telecop. +358 10 709 3279 Telecop. +358 10 709 3410

Tel. +358 10 709 0000

Business ID 0773744-3 Registered Office: Vaasa

jb^probjbkq ob`loa Service, Wärtsilä Finland Oy Engine section

Engine type

Ref.

Date

11 Crank Mechanism

20

WFI–S

12.03.2004 01

Installation name: Fuel viscosity (cSt):

Engine type: Ambient temperature:

Small end bearing

Issue

Document No.

Page

2011V007GB

1(1)

Engine No: Engine running hours:

Measuring points

Bearing bush ID: Bearing nominal diameter, assembled Bearing wear limit, assembled

= 90,050-90,102 mm = 90,140 mm

Diameter of the bearing to be measured with a dial gauge. Note: Pay attention not to damage the running layer.

1

2

3

4

Cylinder number 5 6

7

8

9

7

8

9

A1 A2 A3 Bearing A4 diameter (deviation in B1 1/100 mm) B2 B3 B4 Component running hours: Remarks/ Manufact. No:

Gudgeon pin

Measuring points

Pin designations:

Pin nominal diameter:

= 89,990-90,000 mm

The diameter to be measured in 4 directions, fill in the min and max measure in the table.

1

2

3

4

Cylinder number 5 6

C min Gudgeon pin C max D min diameter (deviation in D max 1/100 mm) E min E max Component running hours: Remarks/ Manufact. No: Date of measurement:

Place:

Name:

Wärtsilä Finland Oy Service, Vaasa

P.O. Box 252 (Tarhaajantie 2) FIN-65101 Vaasa, Finland

Telecop. +358 10 709 7355 Telecop. +358 6 356 7339

Tel. +358 10 709 0000

Wärtsilä Finland Oy Service, Turku

P.O. Box 50 (Stålarminkatu 45) FIN-20811 Turku, Finland

Telecop. +358 10 709 3279 Telecop. +358 10 709 3410

Tel. +358 10 709 0000

Business ID 0773744-3 Registered Office: Vaasa

jb^probjbkq ob`loa Service, Wärtsilä Finland Oy Engine section

Engine type

Ref.

Date

14 Valve Mechansim, Camshaft

20

WFI–S

12.03.2004 01

Installation name: Fuel viscosity (cSt):

Issue

Engine type: Ambient temperature:

Camshaft bearing

Document No.

Page

2014V008GB

1(1)

Engine No: Engine running hours:

Measuring points

Bearing designations: Bearing nominal diameter, assembled Bearing wear limit, assembled

= 140,125-140,190 mm = 140,210 mm

Diameter of the bearing to be measured with a dial gauge. Note: Pay attention not to damage the running layer.

1

2

3

4

Bearing number 5 6

7

8

9

10

8

9

10

A1 A2 A3 Bearing A4 diameter (deviation in B1 1/100 mm) B2 B3 B4 Component running hours: Remarks/ Manufact. No:

Camshaft bearing piece

Measuring points

Shaft designations: Camshaft journal nominal diameter

= 139,975-140,000 mm

The diameter to be measured in 4 directions, fill in the min and max measure in the table. Camshaft bearing piece to be measured with micrometer.

1

2

3

4

Bearing number 5 6

7

C min Camshaft C max diameter (deviation in D min 1/100 mm) D max Component running hours: Remarks/ Manufact. No: Date of measurement:

Place:

Name:

Wärtsilä Finland Oy Service, Vaasa

P.O. Box 252 (Tarhaajantie 2) FIN-65101 Vaasa, Finland

Telecop. +358 10 709 7355 Telecop. +358 6 356 7339

Tel. +358 10 709 0000

Wärtsilä Finland Oy Service, Turku

P.O. Box 50 (Stålarminkatu 45) FIN-20811 Turku, Finland

Telecop. +358 10 709 3279 Telecop. +358 10 709 3410

Tel. +358 10 709 0000

Business ID 0773744-3 Registered Office: Vaasa