Service Experience 2006, ME and MC Engines.pdf

7/27/2019 Service Experience 2006, ME and MC Engines.pdf

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MAN B&W Diesel A/S, Copenhagen , Denmark

Contents:

Service Experience 2006, ME and MC Engines

Introduction

The ME/ME-C Engine Series

The ME concept

Hydraulic cylinder unit

Hydraulic power supply

Engine Control System

Alpha Lubrication system

ME engine service experience summary

The MC/MC-C Engine Series

Time Between Overhaul for the latest generationof MC engines

Scuf ng investigation

Bearings

Cracks in the camshaft housing for K98 engines

Concluding Remarks


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Service Experience 2006, ME and MC Engines

Fig. 1: General view, 12K98ME installed in a container ship

Introduction

The introduction of the electronicallycontrolled camshaft-less low speeddiesel engines is proceeding rapidlywith many ME engines ordered and,consequently, many ME engines enter-ing service. At the time of writing, morethan 250 ME engines are on orderor have been delivered. This numberproves the markets acceptance of this technology. Of the ME engines, 50are in service, and they range from theL42ME engine up to the K98ME/ME-Cengines. An example is shown in Fig. 1.

Although the ME technology may seembrand new to many in the industry,MAN B&W Diesel has been devotedto the development of electronicallycontrolled low speed diesels for a longtime, actually since the early 1990s.

The rst engine featuring the ME tech-nology was a 6L60MC/ME, the nameindicating that it was originally built as aconventional MC engine with camshaft,and then later rebuilt into an ME engine.

The ME version of this engine has nowlogged about 30,000 running hoursand it has, throughout this period, beenused to ne-tune the ME technology.

The main objectives for the ME-tech-nology are:

Improved fuel economy at all loadpoint, Fig. 2

Flexibility with respect to presentas well as future emission require-ments, Fig. 3

Easy engine balancing/adjustability,Fig. 4

System integration(example, Fig. 5: Alpha Lubricatorfully integrated in the ME-system)

Smokeless operation

Stable running of very low load

1.

2.

3.

4.

5.

6.


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All these objectives have been accom-plished to a very satisfactory level onthe rst ME engines in service, g.6.Future updates and ne tuning withnew releases of the control softwarefurther enhance advantages of the MEconcept.

Fig. 5A: System integration example: Alpha Lubricator

0

100

200

300400

500

600

700

800

900

1000

1100

1200

1300

16:37 16:38 16:39 16:40 16:41 16:42 16:43 16:44 16:45 16:46

N O

x [ p p m ]

2003-02-17

1 40 1 50 1 60 1 70 1 80 1 90 2 00 2 10 2 20 2 300 0

20 100

40 200

60 300

80 400

100 500

120 600

140 700

160 800

Cylinder Pump

2003-02-17

1 40 1 50 1 60 1 70 1 80 1 90 2 00 2 10 2 20 2 300 0

20 100

40 200

60 300

80 400

100 500

120 600

140 700

160 800Cylinder Pump

Economy mode Low NO X mode

Time

Fig. 3: Flexibility with respect to emission

Adjustment of p max & MIP

Fig. 4: Easy engine balancing/adjustability

-4

-2

0

2

4

6

8

0 20 40 60 80 100 120L oa d in %

%

MC-CME-C economyME-C low NO x

Fig. 2: Improve fuel economy at all load point

Other ME features realized are:

Real camless operation with eitherengine driven or electrically drivenstandard industrial pumps for the hy-draulic power supply

Standard exibility with respect tochanging between HFO and MDOoperation

Simplicity is kept by low number of components (e.g. only one NC valveper cylinder)

Furthermore the number of assemblypoints are kept low by having onlyone high pressure oil system

Cylinder control computers are keptaway from areas with high heat expo-sure in order to limit thermal heating

Apart from the ME-specic featureslike OROS combustion chamber withslide fuel valves, nimonic exhaustvalves with W-seat securing long timebetween overhaul and very satisfac-tory cylinder condition.


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The ME/ME-C EngineSeries

The ME concept The ME engine concept consists of aservo-hydraulic system for activationof the fuel oil injection and the exhaustvalves. The actuators are electronicallycontrolled by a number of control unitsforming the engine control system,see Fig. 7.

The fuel injection is accomplished bypressure boosters which are mechani-cally simpler than the fuel pumps onconventional MC engines. The fuelplunger on the ME engine is driven by apiston actuated with pressurised con-trol oil from an electronically controlledproportional valve as the power source.

Also, the exhaust valve is opened hy-draulically and closed by an air spring,as on the MC engine. Similar to the fuel

injection pressure booster, the elec-tronically controlled exhaust valve actu-ator is driven by the pressurised controloil which, for the exhaust valve, is fedthrough an on/off type control valve ora proportional type control valve.

In the hydraulic loop, see Fig. 8, lubri-cating oil is used as the medium. It isltered through a ne lter and pres-surised by a hydraulic power supplyunit mounted on the engine. A separatehydraulic oil system is optional. Further-more, separate electrically driven mainpumps are optional.

From the hydraulic power supply unit,the generated servo oil is fed throughdouble-wall piping to the hydrauliccylinder units, see Fig. 9. There is onesuch unit per cylinder. Each unit con-sists of a fuel oil pressure booster andan exhaust valve actuator. A Fuel Injec-tion and Valve Actuation (FIVA) controlvalve is mounted on the HCU. On early

ME engines ELectronic valve Fuel Injec-tion (ELFI) and ELectronic Valve Actua-tion (ELVA) control valves are mounted

Fig. 6: ME/ME-C list of references

Type InService

K98ME 3K98ME-C 4S90ME-C 2S70ME-C 12L70ME-C 3S60ME-C 16L60ME 1S50ME-C 8L42ME/MC 1

Total 50

More than 250 engines on order/deliv-ered

Spacerfor basicsettingof

pumpstroke

Stroke adjusting screw

Cylinderlube oilinlet

200 bar servooilsupply

Signal for lubricationfromcontroller

Inductive proximity switchforfeed-back signal for controlof

piston movement

Injection plungers

Actuator piston

Drainoiloutlet

Outletsfor cylinder linerlubeoil injectors

Saves cylinder lube oil

Save 0.3 g/bhpcylinder oil

Fig. 5b: System integration example: Alpha Lubricator

This paper will describe the service ex-perience obtained with the commercialME and ME-C engines in service.

For the MC/MC-C engine series, thefeedback from service has over thelast 4-5 years resulted in an extension

of the Time Between Overhauls (TBO).We have not yet fully experienced thebenets of this development. However,the latest feedback from service indi-

cates that 5 years between major over-hauls are looking to be realistic. It willbe discussed how this development

can benet different operators. Also thedevelopment in relation to the cylindercondition with focus on cylinder oil con-sumption will be touched on.

The latest feedback from service in re-lation to bearings will also be outlined,as well as the cracks in the camshafthousing structure of the K98 engineswill be described and solutions will beshown.


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Fig. 7: Engine Control System (ECS)

Fuel 10 bar Hydrauliccylinder unit

Alphalubricator

Servo oilreturn to sump

Fine aut. filter

Piston cooling+ bearings

From sump

Main lubepump

Safety andaccumulatorbloc k

EL. drivenhydraulic pumps

Engine -drivenhydraulic pumps

Servo oil

Fuel oil pressurebooster

Exhaust valve actuator

Cyl. 1 Cyl. 2 Cyl. 3 Cyl. 4 Cyl. 5 Cyl. 6CCUCCU CCU CCU CCU CCU

200 barFIVA

Fig. 8: Hydraulic loop of the ME engines

on the HCU. Also the Alpha Lubricatoris mounted on the HCU.

It should be realised that even thoughan ME engine is simple to operate,training of crews in the ME technologyis important in order to ease the under-standing and avoid any confusion andanxiety that could otherwise occur. Tofacilitate this, MAN B&W Diesel has setup an ME training centre including acomplete ME simulator, so that crewscan get hands-on training at our worksin Copenhagen. Fig. 10 shows the MEsimulator in Copenhagen. Mobile ver-sions of such ME simulators are pres-ently being built in order to be able totrain crews and customers at otherlocations than Copenhagen.


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Exhaust valve actuator

FIVA valve Integrated Alpha Lubricator

Fuel oil pressurebooster

Fig. 9: Hydraulic Cylinder Unit (HCU)

Fig. 11: 7S50ME-C, cylinder condition after 10,717 running hours

Fig. 10: ME Training Centre with complete ME simulator Fig. 12: 12K98ME, port inspection shows excellent condition

Fig. 13: 12K98ME, crosshead bearing and main bearing

In general, operators have reported,and thus conrmed, the expectedbenets of the ME technology, suchas lower FOC (Fuel Oil Consumption),better balance between cylinders, bet-ter acceleration characteristics andimproved dead slow performance.

Also, the detailed monitoring and diag-nostics of the ME engine provide easieroperation and longer times betweenoverhauls, and indeed the ME technol-ogy makes it much easier to adjust theMean Indicated Pressure (MIP) andp max . This is carried out via the MainOperating Panel (MOP) in the controlroom, ref. Fig. 7.

Operators have also found that whenoperating in rough weather, there isless uctuation in engine rpm com-

pared to an engine with camshaft-driv-en fuel injection. Importantly, ownersof ME engines in service for at longerperiod of time report savings in fuel oilconsumption in the range of up to 4%,when comparing to a series of sistervessels, having the camshaft equippedcounterpart type of engines. Apartfrom the inherent better part load fueloil consumption of an ME engine, onereason for the reported improved fuelconsumption gures is that the ME en-gine makes it very easy to always main-tain correct performance parameters.

Fig. 11 demonstrates the cylindercondition on the rst 7S50ME-C after10,717 running hours, and the condi-tion is perfect. As regards the cylindercondition, in particular, observations


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ResilientMountings

Fig. 14: ELFI valve, DC-DC converter coming off due to vibration of PCB

Fig. 15: ELFI valve, PCB secured by resilient mountings

Fig. 16: ELVA valve, location og high-response valve spool

so far indicate that we can expect animproved cylinder condition in general,probably owing to the fact that thefuel injection at low load is signicantlyimproved, compared to conventionalengines.

Also other engines have been closelyfollowed up with a view not only to MErelated parts, but also to check thecondition of ordinary components andareas of interest. Figs. 12 and 13 showpictures taken on the rst 12K98MEengine.

Hydraulic cylinder unit The hydraulic cylinder unit, of whichthere is one per cylinder, consists of ahydraulic oil distributor block with pres-sure accumulators, an exhaust valveactuator with ELVA control valve anda fuel oil pressure booster with ELFIcontrol valve. Each individual HCU isinterconnected by double-wall piping,through which the hydraulic oil is led.

After delivery of the rst 20 ME engines,the ELVA and ELFI valves were substi-tuted by one common FIVA valve con-

trolling both the exhaust valve actuationand the fuel oil injection.

ELFI valvesOn the Print Circuit Board (PCB) com-ponents have come loose due to vibra-tions. Fig. 14 shows a DC-DC converterwhich has come off. Improvements bymeans of resilient mountings have beenintroduced on all vessels in service withELFI valves, and performance has beengood hereafter, see Fig. 15 .

ELVA valvesEarly service experience proved thatlow ambient temperatures, as often ex-perienced during shop tests in the win-ter season, gave rise to sticking high-response valve spools in the ELVA valvedue to low hydraulic oil temperatures.

The diameter of the spool was reducedin order to obtain correct functioningof the high-response valve as shown in

Fig. 16.

High-responsevalve spool


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Fig. 20: FIVA valve, resilient mountingof PCB

Fig. 17: ELVA valve, sticking high- responsevalve spool

Sticking marks

A

B

Fig. 18: ELVA valve,A: resistor broken due to vibrations

B: damping secured with silicon glue

Fig. 19: ELVA valve, reinforcement by heat shrink tubes

Heatshrink tubes

However, a quality problem with toosmall clearances between the spooland the housing in the high-responsevalve has been encountered in service.

This has led to a sticking spool, Fig. 17.

In such a case the control system en-counters improper lifting of the exhaustvalve and fuel is, as a consequence,stopped to the unit in question. Engine

10 x 5 x 5 mm

running in one-cylinder misring is thenexperienced. A change of ELVA valvesto 100% quality controlled units hastaken place.

Also on the ELVA valves, we have seencomponents breaking off due to vibra-tions, like the resistor shown in Fig. 18.

The x has been to apply silicon glue asdamping media.

Wires breaking in the crimpings in theconnector because of vibrations havealso been experienced. The connectionbetween the wire and the connector

n or ma l r an ge ext en ded r an ge

Fig. 21: Control valve, extended vibrationtesting

pin is reinforced by a heat shrink tube,Fig. 19.

FIVA valvesIn general, the FIVA valves have seenmuch fewer vibration-related troublesthan the ELFI and ELVA valves. A resil-ient mounting design, Fig. 20, has been

applied from the beginning and an ex-tended vibration testing (up to1 kHz) has been used, Fig. 21.


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Growth ondiameter: 6 m

Fig. 22: FIVA valve, growth of main spool

Self-adjustingdamper piston

Hydraulicnut/measuringcone

Outlet lube oil

Damper

Air inlet

Inlet lubeoil

Exhaustvalve

feedback sensor

Fig. 23: Exhaust valve feedback sensor

Flange

Outer pipe

Sealing ringScrew Inner pipe

Sealing ring

Sealing ring

Slidingbearing

FlangeOuter pipe Inner pipe

Sealing ringScrew

Fig. 24: Double-wall piping, old sealing arrangement

Fig. 25: Double-wall piping, new sealing arrangement

In a few cases, we have seen growth of the main spool in the FIVA valve. Fig. 22shows a main spool where the diam-eter has grown 6 micron. The reasonhas been put down to improper heattreatment of the main spool and theprocess has been corrected.

Feedback sensors for exhaust valveand fuel oil boosterThe sensor signal was out of range inone end of the exhaust valve strokeon certain engines, which resulted in asignal failure alarm. This was caused byincompatibility between the sensitivityof the sensor and the material of thecone on the exhaust valve. The calibra-tion of the sensor has been changed.

The plastic sensor tip has broken looseor it has been pressed in, Fig. 23. Thetip has been reinforced and the internalmoulding in the tip has been improved

by process improvements.

Double-wall pipesProblems with hydraulic oil leakageshave been seen during shop tests onthe largest engines because of sealdamage. The main reason for theseproblems was lack of quality from anew sub-supplier of these sealings. Inany case, it was decided to upgradethe seal design for the 80-98 bore en-gines, see Figs. 24 and 25.

In the new design, the sealing functionand the function of carrying the weight


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Fig. 26: Maintenance of accumulators

Fig. 27: Hydraulic power supply diagram

of the piping and hydraulic oil havebeen divided. The sealing function isnow taken care of by the U-cup seal-ings and the carrying function by theguiding tapes. Furthermore, a scraperring has been introduced in order toensure reliable performance of the out-er sealing. Additional lubrication of thesealings is permanently present by thelow pressurisation of the outer pipe.

Maintenance of accumulatorsRegarding accumulators, we have seencases of damage to the diaphragmsinside the accumulators. Maintenanceof accumulators was the subject of the rst dedicated Service Letter forME engines. Fig. 26 summarises our

recommendations, which are to adjustthe nitrogen pressure to 95 bar, check MiniMess for leakages and apply the

MiniMess cap after check and charg-ing. Furthermore, it is recommendedto check the nitrogen pressure with sixmonths intervals.

Hydraulic power supply The hydraulic power supply unit pro-duces the hydraulic power for thehydraulic cylinder units. The hydraulicpower supply unit includes both theengine-driven pumps, which supply oilduring engine running, and the electri-cally driven pumps, which maintain thesystem pressure when the engine is ata standstill. The engine-driven pumpsare coupled through a gear drive or achain drive to the crankshaft, and areof the electronically controlled variabledisplacement type.

The hydraulic power supply system,Fig. 27, features, as standard, a numberof engine-driven pumps and electrically

driven start-up pumps. The engine-driven pumps are axial piston pumps(swash plate types), and the ow iscontrolled by a proportional valve. Onsome K98 engines, we have initiallyseen problems with noise from thesepumps during astern operation. As apreliminary countermeasure, this haseffectively been cured by installingbooster pumps securing that cavita-tions on the suction side of the swash

Summary:- Revised charge pressure

95 +0/-5 bar- Check for leakages at MiniMess- Always mount the MiniMess

cap after check and charging

Sealings : Internal primary and secondary sealing andsealing for screw-in thread made of Buna N

Screw-in thread: Different kinds of thread are available

Option: Satety devices against vibration Safety device against torsion and loosening of metal capmade of Buna N


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Fig. 28: Flexible hoses on K98

Fig. 30: Pump safety shaft, initial design

Fig. 29: Double-wall piping re-design on 6S90ME-C

Re-designInitial design

Pump end

Gear end

Fig. 31: Pump safety shaft, new shaft assembly with central bolt

Pump endHigh friction disc

Gear end

plate pumps will not occur duringastern running. A permanent counter-measure has been to equip the largestengines (e.g. 12K98ME/ME-C) with

more swash plate pumps of a smallersize. These smaller-size pumps do nothave problems with astern operation.

For certain engine types, star t-uppump capacities have been increasedto be able to deliver sufcient start-uppressure on one start-up pump within90 seconds.

On new engines, the hydraulic oil lterhas been re-specied from mess size10 micron to mess size 6 micron. Thereason for this has been to prolong thelifetime for various components sub-

jected to wear.

Hydraulic pipesCases of cracked hydraulic pipes forthe servo oil to the swash plate pumpshave been seen, and investigationshave proved these cracks to occur dueto vibrations. To avoid this, the pipedimension has been changed and ex-ible hoses have been introduced as an

extra precaution, see Fig. 28.

On the 6S90ME-C engine, the dou-ble-wall piping connecting the aftmost


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Fig. 32: 7S50ME-C, gearbox for engine-driven hydraulic pumps

Fig. 33: MPC board, failure of channels 70 and 71

DC-DC converter

Channels 70 and 71

HCU and the HPS has been rede-signed, Fig. 29. Disintegration of thehorizontal parts at the HCU and HPSwas experienced at a shop test whenthe outer pipe was pressurised. Recti-cation was carried out and veried dur-ing the shop test on the rst 6S90ME-Cengine.

Shafts for engine-driven hydraulicpumpsInitially, teething problems have in-cluded breakage of the shafts for theengine-driven hydraulic pumps.

The purpose of the shaft design is toset an upper limit to the transferredtorque, so as to safeguard the commongear in the event of damage to a pump.However, the shafts broke due to a toolow torque capability.

The design of the shafts has beenchanged in order to increase the mar-gin against breakage. The initial design

shown in Fig. 30 featured six studs anda frictional connection, and the boltswere sheared at a too low torque.

The new design shown in Fig. 31 hasa centre bolt which tightens together africtional connection. No problems havebeen experienced with this design.

Besides this, we have introducedforced lubrication of the shaft assem-bly to counteract cases of wear of thesplines for the shaft and gear wheel.Splines are now also hardened.

GearboxFig. 32 shows an example of an inspec-tion of the gearbox for the pump driveafter 3,000 hours. The condition of thegearbox was found to be excellent. Theonly modication introduced is a tip re-lief on the teeth in order to prevent initialrunning in marks.

Engine Control System

MPC boards The ME Engine Control System (ECS)consists of a set of Multi Purpose Con-trollers (MPCs). These are generallyused in Auxiliary Control Units (ACU),Cylinder Control Units (CCU), EngineControl Units (ECU) and Engine Inter-face Control Units (EICU), and they areidentical from a hardware point of view.Once connected in the individual ap-plication (CCU, ACU, ECU or EICU), theMPC will load software according tothe functionality required.

On the MPC, channels 70 and 71 havebeen damaged in some cases. Thiswas caused by wrong or uctuatingsignals at the outputs. Consequently,a breakdown of a capacitor in the DC-DC converters (Fig. 33) took place. Thiswas determined to happen when 24V

or higher voltages (noise, etc.) wereapplied backwards into the terminals


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Transorbers

Fig. 35: PCB, broken copper layers

Fig. 34: MPC board ( Power Filter Board) isolation failure

Plated through - hole:Copper cylinder in the hole

4.

5.

6.

Glassfiber

Insulationand glue layer

The conductor in layer 5 is connectedto the conductor in layer 2 via thecopper in the plated through - hole

A A

Copperlayers

A-A 1.

2.

3.

of the channels. Initially, the AO-DODaughter boards of the MPCs in pro-duction were improved by applying atransorber across the output terminals.Later, the board has been redesigned.

Due to inferior quality of a component(a transorber) used in the power lterboard of the MPC, Fig. 34, isolationfailures were experienced. Certain s itu-ations caused too high leak-currentsthrough the transorbers. Manufacturersof the transorbers have been black-listed and transorbers from reliablemanufacturers have been applied.

Production failures in the Printed CircuitBoards (PCBs) have caused broken con-nections in the inner layers, Fig. 35. ThePCB base material has been changedto a type with a lower thermal expan-sion coefcient in the cross-sectional

direction. Furthermore, the copperlayer thickness in plated-through holeshas been increased to full the speci-cation.

We have experienced bend pins in thePCB to PCB connectors. This is a pro-duction failure, and additional produc-tion tests have been added on the fullyassembled units to sort out erroneousunits for repair.

A general problem has been that loose,unused screws in terminals on PCBsmounted on the engine are worn byvibrations, thereby causing emission of metallic dust in the area near the ter-minal involving a risk of causing shortcircuit, Fig. 36. Instructions have beenreleased requiring that all screws, alsounused, must be tightened with attorque screwdriver.

Main Operating Panels (MOPs) The present execution of the ME en-gine control system comprises oneMain Operating Panel (MOP) which isan industrial type PC with an integrated


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Fig. 38: ME-system, control diagram (initial version)

ECU A ECU B

P U M P 3

P U M P 2

M M M

P U M P 1

F i l t e r

P U M P 1

M

P U M P 2

M

HPS

ACU 1 ACU 3ACU 2

On Bridge

In Engine Control Room

In Engine Room/On Engine

ECU A

EICU A EICU B

ECU B

ADMINISTRATION PCBACK-UP FOR MOP

BRIDGE PANEL

LOCAL OPERATINGPANEL - LOP

P U M P 3

P U M P 2

M M M

P U M P 1

F i l t e r

P U M P 1

M

P U M P 2

M

HPS

AUXILIARYBLOWER 1

AUXILIARYBLOWER 2

ECR PANEL

CRANKSHAFTPOSITION

SENSORS - CPS

ACU 1CCUCylinder 1

CCUCylinder nACU 3ACU 2

MCU

SBU

BCU

ALS

SAVCylinder n

HCUCylinder n

ALS

SAVCylinder 1

HCUCylinder 1

ECU - Engine Control Unit

EICU - Engine Interface Control UnitACU - Auxiliary Control UnitCCU - Cylinder Control UnitHPS - Hydraulic Power Supply

SAV - Starting Air Valve

ALS - Alpha Lubricator System

MOP - Main Operation Panel

LOP - Local Operation Panel

MCU - Master Control UnitBCU - Back-up Control UnitSBU - Switch Board Unit

CPS - Crankshaft Position Sensors

MAIN OPERATINGPANEL - MOP

nrednilyC1rednilyC

relation to arrangement and installation.For instance, the display can either bemounted in the control room consoleor alternatively in an optional cabinet(bracket) for use as a desk top type.

The new conguration will, as a con-sequence, only use the 24V supply. Inthis way, the 110V Uninterrupted PowerSupply (UPS) can be omitted.

NetworkVessels in service have experiencedalarms concerning failure in the com-munication between the individualMPCs due to momentarily overloadof the network. The overload has notaffected the operation of the enginebecause of the redundancy of the sys-

tem. An updated software version hassolved the problem.

Alarm statusOne area of concern has been the toomany and often less relevant alarms.

The original ME control software hashad a large number of less relevantalarms. In many cases, the alarms onlyhad minor importance for the enginerunning condition, and the operatingcrews could not do anything to rectify.Control programmes and softwarehave been upgraded and modied toroot out less relevant information.

Tacho systemInitially, the ME tacho system was de-signed on the basis of trigger segmentswith a sine-curved tooth prole mount-ed on the turning wheel. The total trig-ger ring was built from eight equal seg-

ments. Two redundant sets of sensorswere applied. This initial tacho systemis relatively expensive, and the system

is also rather time consuming to com-mission on test bed/sea trials. Today,this system is only specied if the freeend of the crankshaft is occupied byother equipment like power take-offs.

The new tacho system is based on op-tical angular encoders installed on thefree end of the crankshaft. This system,consisting of two redundant encoders,is easier to install and adjust. Fig. 37shows the two systems.

When properly adjusted, both tachosystems have, in general, given riseto only minor concern. However, oneevent where an incorrectly installed(tightened) Geislinger damper fell off the crankshafts has been experienced.

This caused damage to both angularencoders, and at the same time result-ing in loss of manoeuvrability.

ME system documentationIn one incident, loss of manoeuvrabil-ity was partly caused by a lack of pre-cise documentation/information. Thishas been rectied by updating both ourinstruction book and by introducingtwo additional alarms.

In order to be able to understand theincident it is necessary to know theprinciple of redundancy applied in theME system. This principle of redun-dancy dictates that no single failuremust stop the engine or prevent furtherpropulsion. However, the consequenceof more failures is undened. This prin-ciple is fully accepted by the classica-tion societies.

The incident occurred on an ME enginewith four (4) engine-driven hydraulicpumps. Control of one of these pumpswas lost. When this happened, theswash plate for the uncontrolled pumpwent to full ahead. In the original ver-

sion of the instruction book, a systemconsisting of only three (3) engine-driv-en pumps is shown, Fig. 38. Each of


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ECU A ECU B

LOCALOPERATINGPANEL - LOP

ACU 1 ACU 3ACU 2

P U M P 2

M M

P U M P 1

P U M P 1

M

P U M P 2

M

P U M P 3

M

P U M P 4

M

P U M P 5

M

S e n s o r s

A c t u a t o r s

S e n s o r s

On Bridge

In Engine Control Room

In Engine Room/On Engine

ECU A

EICU A EICU B

ECU B

Backup Operating PanelMOPB

BRIDGE PANEL

LOCALOPERATINGPANEL- LOP

AUXILIARYBLOWER 1

AUXILIARYBLOWER 2

ECR PANEL

ACU 1CCUCylinder 1

CCUCylinder nACU 3ACU 2

SAVCylinder n

MAIN OPERATING PANELMOP A

Fuelboosterposition

Cylinder 1

Exhaustvalve

positionCylinder 1

Exhaustvalve

positionCylinder n

Fuelboosterposition

Cylinder n FIVAValve

Cylinder nAL

Cylinder n

Angle Encoders

Marker Sensor

P U M P 2

M M

P U M P 1

P U M P 1

M

P U M P 2

M

P U M P 3

M

P U M P 4

M

P U M P 5

MAUXILIARYBLOWER 3

AUXILIARYBLOWER 4

AUXILIARYBLOWER 5

A c t u a t o r s

ALCylinder 1

SAVCylinder 1

FIVAValve

Cylinder 1

On the basis of the above incident, inaddition to updating the instructionbook, we have added the following two(2) alarms:

Alarm for Pump Failure if an ACUor a pump controlling ECU fails

Alarm for Lost Manoeuvrability if two or more pumps fail.

Having informed the crews of the aboveimprovements, similar incidents will beavoided in future.

Alpha Lubrication system The ME engine has the advantage of an integrated Alpha lubrication system,which utilises the hydraulic oil as themedium for activation of the main pis-ton in the lubricators. Thus, a separatepump station and control are not need-ed compared to the MC counterpart.

Most of the ME engines in service fea-ture this system and, in general, theservice experience has been good,with low cylinder liner and piston ringwear rates giving promising expecta-tions of long intervals between over-hauls.

On certain engines of the S50ME-Ctype, we have experienced a number of teething troubles in the form of brokenlubricator plungers as well as damageto the main activator piston.

In order to alleviate these problems,a revised design of the plungers andmain pistons has been introduced onthe Alpha Lubricators.

A new actuator piston with a reinforceddisc without holes and damper hasbeen introduced, together with a newstroke limiter. The solenoid valve hasalso been modied by introducing a

damping orice to reduce the hydraulicimpact, which previously inuenced theproblems observed.

1.

2.

these pumps are controlled by an ACU(Auxiliary Control Unit). However, thecontrol of a system with four or moreengine-driven pumps is not described.

In the updated instruction book, a sys-tem with up to ve (5) engine-drivenpumps is shown, Fig. 39. It can be

seen that if pump Nos. 4 and 5 arepresent they are controlled by ECU A and ECU B, respectively.

The incident described above devel-oped further as the crew took the de-cision to shift the engine control fromECU A to ECU B and dismantle ECU A.

According to the updated instructions,the pump control for pump No. 4 isthen also lost. Pump No. 4 then goes tofull ahead and astern operation is no

longer possible.

Fig. 39: ME-system, control diagram (updated version)


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18

The system provides wider optionsfor adjustment of the engine

In spite of its complexity, the systemis divided by several standard mod-ules, thereby, allowing the crew toquickly locate a faulty module

No special periodic maintenance isrequired for the electronic parts

The modules design allows easy andrapid replacement

The modules and control units of the system have a built-in centralprocessing unit (CPU) that ensurescontinuous self-monitoring of thetechnical condition, and an alarm isgiven to the crew in the event of anyabnormalities

The communication between the

operators at the three remote controlstations, i.e. the bridge, the starboardwing, and the engine control room,and the control units of the system iseffected by means of a special indus-trial network that reduces the numberof wires needed for data transferring,i.e. reliability is improved.

We take this as a proof of the ME en-gines gaining momentum in the marketand most certainly presenting operat-ing advantages to owners and crews.

The MC/MC-C EngineSeries

Time Between Overhaul forthe latest generation of MCenginesOver the last 4-5 years, the TimeBetween Overhauls (TBO) has beengradually extended in our written mate-rial describing typical obtainable TBOs,Fig. 40.

This development has triggered thewish to extend TBOs further, and forcertain ship types (e.g. VLCCs), it hasprompted investigation into whether32,000 hours (or 5 years) betweenoverhauls are realistic.

As the basis for the investigation, wehave chosen the S90MC-C/ME-Cengine series as a representative forthe newest generation of MC engines.

This engine series has been designedand delivered with the newest featuresavailable for the MC/ME engines:

- OROS combustion chamber withhigh topland piston

- Cylinder liner with optimised liner walltemperature

- Alu-coated piston rings, ControlledPressure Relieve (CPR) top ring

- Alpha Lubricator in ACC mode(0.19 g/bhphXS%)

- Exhaust valve: Nimonic spindles andW-seat bottom piece

- Slide fuel valves

Approximately 40 vessels, Fig. 41, with6S90MC-C/ME-C engines have beenused to back-up the claim that TBOs of 32,000 hours (or 5 years) is a realistic

option.

On the vessel M/T Maria Angelicous- sis (equipped with a Hyundai-built

Additionally, steel spacers have beentted below the return spring to re-move the turning effect created fromcompression of the spring and herebyaffecting the alignment of the smallplungers.

In the event of a low engine room tem-perature, it may be difcult to keep thecylinder oil temperature at 45C in theME Alpha Lubricator mounted on thehydraulic cylinder unit.

Therefore, we have introduced insula-tion and electrical heating of the cylin-der oil pipe from the small tank in thevessel and of the main cylinder oil pipeon the engine.

ME engine serviceexperience summary The comments presented in this paperare all based on actual feedback expe-

rience from owners and ship crews.

All issues are addressed continuouslyas they occur, so as to control andeliminate teething troubles immediately.

Some of the very positive feedback that we have received, by way of state-ments received from operating crews,are summarised below in bullet points:

Engines of this type allow a consider-able saving of fuel and cylinder oil

The electronic control system of theengine allows supervising of practi-cally all operating processes, such as:lubricator management, cylinder oilconsumption control, load distributionon cylinders, cylinder cut-off in theevent of a malfunction without stop-page of the main engine

A considerably smaller amount of fuel deposits from combustion in the

scavenge air boxes and the exhaustgas economiser is observed


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Fig. 40: Time Between Overhaul (TBO), guiding intervals

TBO S90MC-C/ME-C

Overhaul guiding interval (Hours)

Component Old MC-C New MC-C ME-C

Piston rings 12-16,000 16,000 24,000

Piston crown 12-16,000 16,000 24,000

Piston crown, rechroming 24,000 24,000 24,000

Exhaust valve, spindleand bottom piece

16,000 16,000 16,000

Fuel valve 8,000 (nozzle)

8,000(spindle guide)

8,000 (nozzle)


8,000 (nozzle)


Fuel pump 16,000 32,000 -

Fuel pressure booster - - 48,000

All pistons overhauled between 22,310-23,955 h

All pistons overhauled in dry dock at 18,233 h

All pistons overhauled between 20,850-21,233 h All pistons overhauled between 9,478-19,715 h

All pistons overhauled between 22,706-23,122 hOverhauled successively

Overhauled successively

0 10.000 20.000 30.000 40.000 50.000Running hours

DAEWOO 5262DAEWOO 5263

Universal Ariake 037Starlight Venture

Sea EnergySea King

Sea Force Athina

Eagle Vienna Ardenne Venture

Spyros Younara Glory

Andromeda VoyagerIrene SL

NichohElizabeth L. Angelicoussis

C. Vision

C. championCrudestar

Astro Corona

Samco AmericaCrude Progress

NeptuneOverseas Rosalyn

Eagle VermontOriental Topaz

Overseas Mulan

NordenergyNordpower

Astro Carina

Eagle Virgnia

Astro CygnusKos

Asti palaia Astro Castor

Maria A. Angelicoussis Antonis L. Angelicoussis

Britanis

Samco Asia

C. Emperor

6S90MC-C engine), piston overhaulshave been carried out successivelyfrom 8,000 hours and upward, seeFig. 42. The piston ring wear is ex-tremely low, and from this point of view indicates innite lifetime.

The vessels M/T Kos and M/T AstroCygnus are also both equipped withHyundai-built 6S90MC-C engines. Inthese engines, the pistons have beenpulled between 20,000-21,000 hoursand 22,000-24,000 hours, respectively.

The pulling of pistons on both these en-gines was caused by internal cokingof the pistons. The reason for this wasfuel oil contamination of the system oil,

Fig. 41: Fleet of VLCCs equipped with 6S90ME-C/MC-C


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Fig. 42: Piston ring wear measurements, prototype 6S90MC-C(M/T Maria A. Angelicoussis)

Fig. 44: Cylinder liner wear, cylinder oil reduction test, 6S90MC-C (M/T Astro Cygnus)

0

0.5

1

1.5

2

2.5

3

3.5

4

0 5000 10000 15000 20000

Wear out limit

Wear rate: Extremelylow Life time basedon wear: "Infinite"

Piston ring wear (mm)

Piston ring hours

Piston Ring Wear Top Ring

0

1

2

3

4

5

0 5000 10000 15000 20000 25000 30000 35000

Ring hours

P i s t o n r i n g w e a r ( m

m )

Wear-out limit

life time?

899,50

900,00

900,50

901,00

901,50

902,00

902,50

903,00

903,50

904,00

0 5000 10000 15000 20000 25000

Engine Hours

Max LinerDiameter (mm)

0.1 / 1000 Hours (mm) Cyl No. 1A Cyl No. 2A Cyl No. 3A Cyl No. 4A Cyl No. 5A Cyl No. 6A

Introduction of ACCto 0.25 g/bhph x S%,min 0.5 g/bhph

ACC 0.21g/bhph x S%,min 0.5 g/bhph

ACC 0.19 g/bhphx S%, min 0.45 g/bhph(Average 0.51 g/bhph)

Fig. 45: 6S90MC-C, cylinder liner wear

Max. liner diameter analysis engine type 'S90MC -C'

900.00

901.00

902.00

903.00

904.00

905.00

906.00

907.00

908.00

909.00

910.00

0 5,000 10,000 15,000 20,000 25,000 30,000

Engine hours

M a x l i n e r d i a m e t e r ( m m )

Wear rate0.05

mm/1000h

Wear out limit

in both cases caused by leaking fuelpumps. Apart from this specic prob-lem, both engines have shown excel-lent cylinder condition with low pistonring wear rates, Fig. 43.

The engine onboard M/T Astro Cygnus has been a test-vehicle for the furthercylinder oil consumption testing ac-cording to the so-called Alpha ACCprinciple (ACC=Adaptive Cylinder oilControl. As can be seen in Fig. 44, thistest has been extremely successful andit indicates further potential for reduc-tion in the cylinder oil consumption.

Below is a summary of the cylindercondition based on all observations onthe S90MC-C/ME-C engine:

Cylinder liner wear rates:0.02-0.07 mm/1,000 hours(Fig. 45)

Piston ring wear rates:Predicted lifetime: 50,000 hours(Fig. 46)

Piston ring groove wear rates:Predicted time between recondition-ing: 40,000 hours (Fig. 47)

1.

2.

3.

Fig. 43: Piston ring wear measurements, 6S90MC-C (M/T Kos)


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Piston Groove Wear (2 mm from edge)Groove 1 - Engine Type S90MC-C

0

0.1

0.2

0.3

0.4

0.5

0.6

5000 10000 15000 20000 25000 30000

Crown Hours

Piston GrooveWear (mm)

Wear out line

Predicted hours betweenreconditioning based on ringgroove wear > 40,000 hours

Excellent condition

K90MC, W-seat and nimonic spindle at 36,400 hours without overhaul

Fig. 48: Nimonic exhaust spindle and W-seat bottom piece

Fig. 46: 6S90MC-C, Piston ring wear Fig. 47: 6S90MC-C, Piston ring groove wear

Fig. 49: TBO: 32,000 hours realistic potential

TBO S90MC-C/ME-C

Overhaul guiding interval (Hours)

Component Old MC-C New MC-C ME-C Realisticpotential

Piston rings 12-16,000 16,000 24,000 32,000

Piston crown 12-16,000 16,000 24,000 32,000

Piston crown,rechroming

24,000 24,000 24,000 32,000

Exhaust valve, spindleand bottom piece 16,000 16,000 16,000 32,000

Fuel valve 8,000 (nozzle)8,000

(spindle guide)

8,000 (nozzle)16,000

(spindle guide)

8,000 (nozzle)16,000

(spindle guide)

8,000 (nozzle)16,000

(spindle guide)

Fuel pump 16,000 32,000 - 32,000Fuel pressure booster - - 48,000 48,000

Piston Ring Wear Top piston ringEngine Type S90MC-C

0

1

2

3

4

5

5000 10000 15000 20000 25000 30000Ring Hours

Piston RingWear (mm)

Wear limit

Predicted lifetimebased on wear> 50,000 hours

The exhaust valve condition also givesrise to optimism with respect to theincrease of TBOs. Fig. 48 shows a bot-tom piece of the W-seat design in com-bination with a nimonic spindle on a

K90MC engine inspected after 36,400hours without overhaul.

With respect to the fuel equipment,32,000 hours seem to be realistic forthe fuel pump itself. The latest experi-ence with the fuel valves conrmsoverhaul intervals of 8,000/16,000hours at which point both the fuel noz-zle and the spindle guide should beexchanged. This experience is basedon fuel valves of the slide valve typeequipped with nozzles of the com-pound type.

Based on service experience in gen-eral, we can conclude that the time be-tween major overhauls of 32,000 hours(or 5 years) is within reach, Fig. 49.

To increase margins further in this re-spect, we will introduce the followingdesign improvements which are notpresent on the 6S90MC-C engines de-scribed in this section:


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Fig. 50: Updated piston ring package (rings 1&2 Cr-plated undersides)

Fig. 51: Piston cooling insert

- Increased scufng margin:modied piston ring package,Fig. 50

- Anti internal coking device:piston cooling insert, Fig. 51

- Ring groove wear reduction:underside chrome plating on rings 1and 2, Fig. 50

For tanker operators, these higher TBOs mean that major overhauls canbe done in connection with the sched-uled dry dockings of the vessels.

For container carrier operators another,more condition-based philosophy, willpay off. Such philosophy is practised onthe K98MC prototype engine on boardM/V Antwerpen Express. Fig. 52 shows

that in this engine, unit No. 1 has stillnot been overhauled after more than41,000 hours of operation.

As a conclusion, we can support thewish to extend TBOs further, and forcertain ship types (e.g. VLCCs) up to32,000 hours (or 5 years) betweenoverhauls are realistic, Fig. 49

Fig. 52: 7K98MC, condition-based overhaul

0 5000 10000 15000 20000 25000 30000 35000 40000 45000 Hours

Cylinder 5

Cylinder 6

Cylinder 2

Cylinder 7

Cylinder 3

Cylinder 4

Cylinder 1

Pistonrings taken to BW lab. forinvestigation(allgood cond)

Chromed test rings Test rings taken to lab

Ring grooves worn, newcrown




Not overhauled yet,41,358h14Jan. 06

K98MC Prototype EngineCondition-based overhaul (Container vessel)

!LUCOATRUNNINGINCOATING

(ARDCOATING MM 2UNNINGINCOATING MM

STRING

NDRING

RDRING

THRING

#HROMEPLATEDBOTTOMFACE

6ERMICULARCASTIRONBASEMATERIAL

(ARDCOATING MM2UNNINGINCOATING MM

#HROMEPLATEDBOTTOMFACE

'REYCASTIRONBASEMATERIAL !LUCOATRUNNINGINCOATING

'REYCASTIRONBASEMATERIAL


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Fig. 53: Piston ring with white layer

Scufng investigationScufng of cylinder liners has becomea recurring incident on some K98 andK90 engines. Other engine types havealso been affected, but to a muchlesser degree. Some of the caseshave been related to traditional servicedisturbances like production mistakesand poor fuel cleaning. However, othercases remain unexplained.

Several design updates of the ringpackage have reduced, but not elimi-nated, the cases.

Data loggingOne big issue in the cases has beenthe lack of accurate and comprehen-sive information of the engine perform-ance at the time of the scufng start.

The unpredictable pattern of scufngnecessitates continuous measuringand recording of data. In the event of

scufng, it is then possible to go back in time and analyse the engine condi-tion at the start of the scufng.

However, the actual start time maybe difcult to establish. A fully devel-oped state of scufng will give indica-tions on the jacket cooling water andthe exhaust gas temperatures, but itmay take days before the condition isserious enough to give clear signals.Unfortunately, at this stage the liner isbeyond recovery.

The widely used liner wall temperaturemonitor, based on two temperaturesensors in the upper end of the liner,one to port and one to starboard side,is a useful instrument, which can detectscufng in the early stages.

Thanks to the good cooperationwith the owners, we have installed adata logger in M/V CMA CGM Verdi (10K98MC-C), a large container liner

trading between China and Europe. The Samsung automation system candisplay all engine parameters in thecontrol room, but only the alarms are

logged. Our data logger receives en-gine parameters, including the signalsfrom the liner wall monitor, from the au-tomation system and stores them every30 seconds. The logger memory hasa capacity for more than six monthsservice.

Scufng

The consequences of scufng havebeen well-known for a very long time the piston ring surfaces, Fig. 53,become rough and hard (cementite),the liner surface is corrupted in severalways and the liner wear rate is astro-nomical, 10 mm/1000 service hourshas been recorded. It is also knownthat if we want to provoke scufng inan experimental engine, the effectivemethod is to inject water through thescavenge ports. Because of the condi-

tions above, the identication of thecauses of service scufng is difcult.However, water ingress, sudden bigpower changes and over-lubricationare main candidates to which there arestraightforward countermeasures.

Designwise, the objective is to increasethe resistance of mainly the piston ringpackage. Lately, success has beenachieved by coating of the surfaceswith high grade materials, Fig. 50.

Water ingressUnder tropical conditions, large quan-tities of condensate water can beformed in the charge air cooler. Tofacilitate drain of this water, a revers-ing chamber is arranged below the aircooler, containing a water mist catcher,and the water is drained by a number of pipes, Fig. 54. To our knowledge, thisarrangement is effective, but because

water ingress is one of the scufng rea-sons, the amount of water drain mustbe included in the measurements. Wehave arranged a set of measuring tankswith the purpose of separating the wa-ter from the airow in the drain pipes.

Sudden, big load changes This happens when a ship leaves a portand accelerates to full speed. The powerincrease is controlled by the governor,which has built-in torque and load limit-

Fig. 54: Drain pipes from charge air coolers

Water mistcatcher


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Fig. 55: Measuring tanks for cooler casing drains Fig. 56:Cylinder unit 8 adjacent to the charge air inlet box

ers. The limiters reduce the rate of powerchange to the recommended values. Thedata logger records the load change, andshould a case of scufng start shortlythereafter, we have a possible cause.

Over-lubricationBesides the waste of valuable lubeoil, over-lubrication of the liners has atleast two negative effects: bore polish,a condition produced by a state of nowear, no corrosion, and build-up of heavy deposits on the side of the pis-ton, which may disturb the oil lm in theliner. We have issued Service Letters(SL385, SL417, SL455), which provideguidance. Furthermore, we have intro-duced the computer-controlled AlphaLubricator, which makes it very easy tofollow the guidance. Presently, the datalogger cannot record the feed rate of the cylinder lubrication.

First resultsThe data logger installation, includingthe measuring tanks for cooler casingdrains, see Fig. 55, was completed on1 November 2005 in Hamburg, and thelog started on 4 November 2005. For

practical reasons, only cylinder units 7and 8 parameters were recorded. Bychance, cylinder unit 8 had the latestring package installed at the same timeas part of a general upgrading. Thepackage had hard-coated ring Nos.1 and 4, see Fig. 50. Cylinder unit 8 isadjacent to the charge air inlet box withthe ap valves if water is carried over,it will hit cylinder unit 8, Fig. 56.

Running-in of cylinder unit 8 rings wasrecorded. A couple of weeks record-ings showed elevated and unstableliner temperatures, Fig. 57. The alu-coat ring package will seal up muchquicker in a cylinder unit. No drain wasrecorded until the Indian Ocean, wherethe seawater reached 30C. During thepassage from Jeddah to Port Klang,three periods with drain were recorded.It should be noted that there is nodrain from the volume after the water

mist catcher. Nevertheless, each of the three incidents gave elevated linertemperatures, the last one above thealarm limit of 150 degrees. Because of the alarm, the chief engineer increasedthe lube oil dosage by 50% in cylinder

unit 8 and in the last hours before PortKlang, the liner temperature was stabi-lised as a result. In Port Klang, the ringsof cylinder unit 8 were photographedthrough the scavenge port and mi-nor damage to the hard-coat couldbe seen, see Fig. 58. Later recordsshowed a stable cylinder unit 8.

Sub-conclusion on rst results The Port Klang incident is the rstdocumented case of a scufng recov-ery. The experience with plain cast ironrings is that increased lubrication andreduced power in the unit will stabilisethe liner temperatures. However, thedestruction of rings and liners cannotbe avoided.

The records showed that no plain wateris passing the water mist catcher, butthe situation with drain from the coolercasing is nevertheless dangerous. Fur-

ther sensor installation will enlighten uswith regard to mist carry-over, Fig. 59


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Fig. 58: Cylinder unit 8 rings, Port Klang

Fig. 57: Log data from rst voyage

CMA CGM VERDI CYL. 8 04-11-2005

0

20

40

60

80

100

120

0 3 - 1 1 - 0 5 0 0 : 0 0 :

0 4 - 1 1 - 0 5 0 0 : 0 0 :

0 5 - 1 1 - 0 5 0 0 : 0 0 :

0 6 - 1 1 - 0 5 0 0 : 0 0 :

0 7 - 1 1 - 0 5 0 0 : 0 0 :

0 8 - 1 1 - 0 5 0 0 : 0 0 :

0 9 - 1 1 - 0 5 0 0 : 0 0 :

1 0 - 1 1 - 0 5 0 0 : 0 0 :

1 1 - 1 1 - 0 5 0 0 : 0 0 :

1 2 - 1 1 - 0 5 0 0 : 0 0 :

1 3 - 1 1 - 0 5 0 0 : 0 0 :

1 4 - 1 1 - 0 5 0 0 : 0 0 :

1 5 - 1 1 - 0 5 0 0 : 0 0 :

1 6 - 1 1 - 0 5 0 0 : 0 0 :

1 7 - 1 1 - 0 5 0 0 : 0 0 :

1 8 - 1 1 - 0 5 0 0 : 0 0 :

1 9 - 1 1 - 0 5 0 0 : 0 0 :

2 0 - 1 1 - 0 5 0 0 : 0 0 :

2 1 - 1 1 - 0 5 0 0 : 0 0 : 0 0

2 2 - 1 1 - 0 5 0 0 : 0 0 :

MA CGM VERDI CYL. 8 19-11-2005 to 21-11-2005

0

20

40

60

80

100

120

1 9 - 1 1 - 0 5

0 0 : 0 0 : 0 0

2 0 - 1 1 - 0 5

0 0 : 0 0 : 0 0

2 1 - 1 1 - 0 5

0 0 : 0 0 : 0 0

2 2 - 1 1 - 0 5

0 0 : 0 0 : 0 0

Rotterdam Malta Suez Jeddah Port Klang

Cond Condsea Temp cyl8 man Temp cyl8 exh

ensate tank1

-EngineRPM

Temp waterensate tank 2

Port Klang

100

110

120

130

140

150

160

100

110

120

130

140

150

160

Fig. 59: Water mist sensor

BearingsSince the last Meeting of Licensees in2002, the positive development withrespect to main bearing damage hascontinued. Despite the heavy increasein the number of main bearings on MC/ MC-C engines, the number of reporteddamage remains at a constant lowlevel, Fig. 60.

For AlSn40 crosshead bearings, wehave had a number of reports (nine (9)altogether) where overlay corrosion


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The following values for the lead contentin the oil system can be used as aguideline:

0-4 ppm lead:normal

5-10 ppm lead:Inspect lters & crankcase for bearingdebris, prepare inspection of crossheadbearings when convenient >10 ppm lead:Inspect lters & crankcase for bearingdebris, prepare inspection of crossheadbearings as soon as possible

Number of damage

AlignmentProcedure finalised

80

70

60

50

40

30

20

10

0

New SLReduced top clearances

Flex-edgeintroduced

Revised top (reduced)Clearance rang introduced

Graphic presentation of the positive influence by theOLS type main bearing, reduced top clearance andoff-set/alignment procedure updates

Aft: Three aft-most main bearings

Centre: Remaining main bearings

Fore: Main bearing 1 & 2

1999 2000 2001 2002 2003 2004 2005 No Water Year

Fig. 61: Crosshead bearing overlay corrosion

Fig. 62: System oil lead content guideline

has been found. In most cases, thishas taken place on bearings where aninterlayer of nickel has been exposed.It is well-known that the nickel has badtribological properties and that a risk of scufng between the bearing shell andcrosshead pin is present, Fig. 61

In all cases of overlay corrosion, exces-sive water in the system oil has beendetected. If the oil system becomescontaminated with an amount of water

Fig. 60: Main bearing damage statistic

exceeding our limit of 0.2% (0.5% forshort periods), corrosion may start. A water content higher than 1% couldlead to critical damage within few daysof operation. A service letter has beensent out in order to inform (reinform)about this phenomenon. In this serv-ice letter, the lead content level in thesystem oil has also been devised as anearly method of detecting overlay cor-rosion of crosshead bearings, Fig. 62.

New bearing monitoring tools with on-line indication of wear on bearings and

an online/ofine oil monitoring systemare discussed in another paper at thisMeeting of Licensees.

Service tests for crosshead bearingswith new synthetic coatings basedon polymer, molybdenum disulphide/ graphite are ongoing and showinggood results, Fig. 63. This technologycan be spread to other bearings thancrosshead bearings where static fric-tion is a limiting factor.

Cracks in the camshafthousing on K98 enginesCracks in the camshaft housing fora number of K98MC-C engines havebeen detected over the last six months.

At the time of writing, six (6) engineshave been affected. In all cases butone, the cracks were found in the cam-shaft bearing pedestal No. 1. Analyseshave shown that bearing pedestal No.1 is approx. 30% more loaded thanother camshaft housing bearing ped-

estals, Fig. 64.Partially corroded overlay,not yet scuffed Overlay completely corroded,away, Ni 100% exposed, partialscufng between Ni-layer and pin

Overlay completely corroded, away,partly scufng between Ni-layerand pin, partly steel-to steel


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Fig. 63: Synthetic overlay on AlSn40 crosshead bearing shell

Crosshead bearing after 2500 rh. Good condition

Fig. 65 outlines on a drawing wherethe crack path is. An example of crack detection can be seen in Fig. 66. At thetime of writing, 90 engines have beenchecked and we intend to inspect allengines in order to know the preciseextent of the problem.

A number of countermeasures/recti-cations have been developed in order

to repair engines with cracks. Further-more, preventive countermeasureshave been developed. In this relation itis important to distinguish between the

-800.000

-700.000

-600.000

-500.000

-400.000

-300.000

-200.000

-100.000

Pedestal 2

Force(N)

0 Deg 180 Deg 360 Deg

Pedestal 4

Pedestal 3

Pedestal 1 + approx. 30%

Fig. 64: Camshaft bearing pedestal loads

two (2) different designs for camshafthousings on the K98 engines, Fig. 67:

A. An integrated camshaft housingwhere the cylinder frame and cam-shaft housing are cast together

B. A separate camshaft housing wherethe camshaft housing is bolted onthe cylinder frame

Cracks have been detected in bothcases. However, repair methods dif-fer somewhat. The following scenarioshave been considered:

6cases with cracks in camshaft bearing support No. 1

2 x10K98MC-C, Cast-on type camshaft housing (2001)

4x12K98MC-C, Bolted-on type camshaft housing (2001)

Case 2

Case 1Case 3 + 4

+ 5 + 6

Fig. 65: Crack paths in camshaft bearing pedestals

Fig. 66: Crack in camshaft bearing pedestal


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Fig. 68: Updated design of camshaft housing (large roundings and size reductionof oil hole) Fig. 69: Hand machining of camshaft housing bearing pedestal roundings

For new engines on which cylinderframes/camshaft housings have notbeen cast, a design change withmore margin for production-relateddeviations has been made. Thisdesign accommodates enlargedroundings and relocation and down-sizing of oil holes closest to the cyl-

inder frame, Fig. 68.

For cylinder frames/camshafthousings already cast but not yetmachined, a modication to the ma-chining is used to introduce largerroundings. In the oil holes, the re-quirements to the surface quality areincreased according to an updatedquality specication. In general, this

1.

2.

Fig. 67: Cylinder frame camshaft housing design

A: integrated design B: bolted-on design

modication is specied on allcamshaft housing bearing pedes-tals. However, for engines alreadyassembled and tested or in vessels,hand-machining has been doneand in such cases only pedestalNo. 1 is modied, Fig. 69.

An alternative method of reducingthe stress level on bearing pedestalNo. 1 is to install a so-called hang-

3.

ing bearing No. 0 in front of cylinderNo. 1, fuel cam, Fig. 70. This meth-od has been used on a number of newbuildings before ship delivery asan alternative to machining of largerroundings.

For engines with cracks propagatingin the main cylinder frame structure(Fig. 65, case 1), a new one-cylinderframe block has been prepared. Thisblock will be exchanged when thevessel docks in August 2006.

Fig. 65, case 2 shows a crack in acylinder frame with an integratedcamshaft housing. However, thecrack has only propagated in thebearing pedestal No. 1 in the cam-shaft housing. Fig. 71 shows theprinciple of two hanging bearingsinstalled hanging from cylinder No.1 base plate. This will completely

ofoad the camshaft bearing ped-estal No. 1 when the bearing shell isremoved. Installation of this solution

4.

5.


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Fuel camExhaustcam

SupportNo. 1

Baseplate

Extrabearing

Fig. 70: Hanging camshaft bearing No. 0 Fig. 71: Repair of cracked bearing support,two hanging camshaft bearings

Fig. 72: Exchange of cracked two-cylinder camshaft housing section

will be carried out in cooperationwith the owner involved in order notto disturb the operation of the ves-sel.

Exchange of two separate cylin-

der camshaft housing sections areplanned on four (4) vessels. Fig. 72shows the work done on the rstvessel on which such operation hasbeen carried out during scheduleddocking.

In situ machining of larger round-ings has been made possible duringshort port stays by means of a dedi-cated machine for this purpose, Fig.73. A number of these machinesare now in operation for enginesentering dry dock, engines alreadyassembled, and as a preventivemeasure for bearing pedestal No. 1on vessels in service.

The above-described items 1-7 cover,at the moment, all our joint effortsto minimise damage made by thesecracks. We will continue throughout2006 to make initiatives in this respectand we will thereby be able to demon-strate effective handling of this case to

the benet of our customers, the ship-owners.

6.

7.

Fig. 73: Machine for in situ machining of roundings

Maching tool operatingRounding after maching


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Concluding Remarks

As mentioned, the reference list of MEengines, see Fig. 6, comprises enginesright from the L42ME to the K98ME/ ME-C, in a fairly even distributionamong about 35 owners of tankers,bulkers and container ships.

The ME/ME-C engines have had a suc-cessful introduction in the market, andthey are well accepted.

As with other products containingnew technology, there has been someteething troubles, most of which wereeliminated quickly.

The service experience for the tradi-tional range of MC/MC-C engines ischaracterised by a stable cylinder con-dition, a stable bearing performanceand a general extension of the realistic

time between overhauls.

When service-related issues, like thecamshaft housing cracks on the K98engine occur, it is of the utmost impor-tance that the licensees and MAN B&WDiesel react coordinated and efcientlytowards our common customers inorder to minimise the impact on theirbusinesses due to such issues. Thecamshaft housing cracking issues haveonce again demonstrated how efcientour joint efforts can be.

Service Experience 2006, ME and MC Engines.pdf

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Transcript of Service Experience 2006, ME and MC Engines.pdf