Service Letter SL12-552/HWC
Action code: WHEN CONVENIENT
Inspection and Monitoring of Crank Train Bearings SL12-552/HWC January 201 2012 2
Concerns Owners and operators of MAN B&W two-stroke marine diesel engines. Dear Sirs
Type: MC/MC-C, MC/M C-C, ME/ ME/ME-C ME-C and ME-B. M E-B.
This Ser vice Lette Letterr give s reco mmen mmendatio datio ns ab out inspe i nspe ctio ction n of the th e
Summary
main, crank pin and crosshead bearings, often referred to as “crank
This Ser vice Lette r gives give s recomme rec ommenn-
train bearings”, by two different methods:
dations about inspection of the main, crank pin and crosshead bearings.
External inspection without opening the bearing
Open-up inspection where the bearing is dismantled
Reference is made to SL08-498/AAB and SL05-460/NHN.
Recommended inspection intervals are updated. Furthermore, recommendations are given with regard to systems for monitoring of the bearings and their working environment.
Yours faithfu fai thfully lly
Mikael C Jensen
Per Rønnedal
Vice Presi dent, Engin eeri eering ng
Senior Manager, New Design
Crosshead bearing inspection and bearing wear monitoring panel
Head ofce (& postal address) MAN Diesel & Turbo Teglholmsgade 41 Teglholmsgade 2450 Copenhagen SV Denmark Phone: +45 33 85 11 00 Fax: +45 33 85 10 30
[email protected] www.mandieselturbo.com
PrimeServ Teglholmsgade 41 Teglholmsgade 2450 Copenhagen SV Denmark Phone: +45 33 85 11 00 Fax: +45 33 85 10 49
[email protected]
Production Teglholmsgade 35 Teglholmsgade 2450 Copenhagen SV Denmark Phone: +45 33 85 11 00 Fax: +45 33 85 10 17
[email protected]
Forwarding & Receiving Teglholmsgade 35 Teglholmsgade 2450 Copenhagen SV Denmark Phone: +45 33 85 11 00 Fax: +45 33 85 10 16
[email protected]
MAN Diesel & Turbo Branch of MAN Diesel & Turbo SE, Germany CVR No.: 31611792 Head ofce: Teglholmsgade 41 2450 Copenhagen SV, Denmark German Reg.No.: HRB 22056 Amtsgericht Augsburg
Service Letter SL12-552/HWC
generally recommended only to open bearing s for inspec-
Contents
tion if justied by observations from the outsid e.
Background
page 2
External inspection of bearings
page 2
Open-up inspection of bearings
page 2
External inspection of bearings
Systems for monitoring and protection of bearings
page 3
The follo following wing insp inspectio ectio ns are recom recommend mend ed to be carrie ca rried d
Recommendatio ns and inspection intervals
page 3
out at regular intervals.
WIOM (Water In Oil Monitoring) suppliers
page 4
BWM (Bearing Wear Monitoring) suppliers
page 4
Inside engine:
BTM (Bearing Temperature Monitoring) suppliers
page 4
Bearing clearance measurements
Bearing edge check
Inspection of crankcase for bearing metal
Crankshaft deection measurement
Background Normally, main, crank pin and crosshead bearings have
Lubrication system:
very low wear rates. Wear rates up to 0.01 mm/10,000 mm/10,000 hrs.
Inspection of oil lters
are considered acceptable, but lower values can be expect-
Oil analysis as described in the “Operation” section of
ed under normal running conditions. Conversely, abnormal
the instruction book.
operating conditions, e.g. pollution of the lubr icating oil, scratches on journals or spark erosion may give rise to signicantly higher wear rates and ultimately to bearin g failure.
Open-up inspection of bearings
Continuous operation with an undetected bearing failure
It is not recommended to open up bearings for inspections
may cause excessive heating, possibly damaging the shaft
unless this is found justied by the above-mentioned exter-
and bearing housing. In particular, in case of a main bearing
nal inspections or by other observations. The only excep-
failure, the repair work may become quite comprehensive.
tion is the open-up inspection of crosshead bearings and
To minimise t he risk of bearing bear ing damage, da mage, and an d possible pos sible con-
crank pin bearings for every three piston overhauls on en-
sequential damage, inspection of the bearings is therefore
gines not tted with the monitoring systems recommended
recommended at regular intervals.
in the following.
Dismantling of a bearing is time-consuming and costly d ue
For a detailed description of the inspections inside the engine
to the work involved. Moreover, Moreover, it involves the risk of d is-
and open-up inspections of bearings, we refer to the “Com-
turbing a well-functioning bearing by entering foreign matter
ponents and Maintenance” section of the instruction book.
or by mistakes made during reassembly. Therefore, it is
Seizure of main bearing shell. Initial cause: spark erosion.
Inspection and Monitoring of Crank Train Bearings. Page 2 of 4 pages
Service Letter SL12-552/HWC
Systems for monitoring and protection of bearings
Recommendations and inspection intervals
Several on-line monitoring systems are available and
MDT recommends tting WIOM and SEDM with a separate
recommended by MAN Diesel & Turbo (MDT) to protect
slip ring for monitoring connected to the alarm system, and
against bearing failure and consequential damage.
BWM connected to the alarm system and safety system (slowdown). If a BWM system is not tted, MDT recom-
Thes e can b e categori cate gori sed in i n two group s:
mends installing temperature monitoring of at least the
Bearing protection systems serving to detect particular
main bearings, as this will protect the bedplate against heat
conditions of the bearing environment that may cause
distortion of the bearing housing. For engines tted with
bearing damage. MDT recommends Shaftline Earthing
WOIM, SEDM and BWM, the following intervals between
Device Monitoring (SEDM) and Water In Oil Monitoring
external inspections of the bearings are recommended.
(WIOM).
Engine protection systems serving systems serving to detect a bearing damage before it develops to cause damage to major parts of the engine. MDT recommends Bearing Wear Mon-
Inspection intervals for engines with recommended monitoring systems (WIOM, SEDM and BWM)
itoring (BWM) and Bearing Temperature Monitoring (BTM). R u n ni ng h o u r s
2,00 0 h
4,0 00 h
8,0 0 0 h
SEDM. Shaftline Earthing Device Monitoring. A well-functioning shaft line earthing system is necessary to avoid
Inspection of crankcase
×
spark erosion in main bearings. Monitoring the electrical
Inspection of oil lter
×
potential between shaft and hull by a separate slip ring con-
Oil analysis
×
nected to the alarm system ensures correct function of the
Clearance measurements
×
Edge inspection
×
Crankshaft deection
×
system. For detailed information, please see SL08-498/ SL08-498/AAB. AAB. WIOM. Water In Oil Monitoring. In several cases, water in
O pen-up inspections of bearings
None
None
N o ne
the lubricating oil has resulted in poor bearing performance. The lead-based overlayer used in crosshead bear-
For all other engines, the below intervals are recommended.
ings is sensitive to water (corrosion), but also main bearings of both the White-Metal and Tin-Aluminium types have been seen to suffer from water contamination. For detailed
Inspection intervals for engines without recommended monitoring systems
information, please see SL05-460/NHN. R u n ni ng h o u r s
2,00 0 h
4,0 00 h
8,0 0 0 h
BWM. Bearing Wear Monitoring is a system that detects wear in any of the three crank train bearings, the main,
Inspection of crankcase
×
crank pin or crosshead bearings, by measuring the posi-
Inspection of oil lter
×
tion of the crosshead assembly in the bottom dead centre.
Oil analysis
×
The BWM B WM system sys tem ha s threshol thre shol d values valu es for fo r rele ase of alar alarm m and engine slowdown, respectively. BTM. Bearing Temperature Monitoring systems have been
Clearance measurements
×
Edge inspection
×
Crankshaft deection
×
Open-up Openup inspect inspections ions of of bearings bearings
Only crosshe crosshead ad and and crank crank pin bearings as mentioned below *)
available for MAN B&W engines for several years. A variety in measuring principles and executions exists, but
* For engines without recommended monitoring systems,
all systems serve to release an alarm/slowdown when a
it is reco recommen mmended ded to t o ope n the cross head and cr ank pin p in
bearing failure has developed to an extent where heat is
bear ings for inspe in spection ction for eve ry three t hree p iston overh overhauls auls of of
developed.
the cylinder in question because of the risk of dirt particles entering the bearings during piston overhaul.
For suppliers of WIOM, BWM and BTM systems, approved or recommended by MAN Diesel & Turbo, please see the enclosed list.
MAN Diesel & Turbo recommends that all data from the above inspections are entered in a log system, computer-
Furthermore, you can contact our PrimeServ department
ised or manually, giving the possibility of viewing trends in
(
[email protected]) for further informa-
the data. Such trends can disclose slow wear in bearings
tion about retrotting bearing monitoring systems.
well before it becomes critical. Preferably, the log should be able to refer to the data taken during sea trial when the vessel was new.
Inspection and Monitoring of Crank Train Bearings. Page 3 of 4 pages
Service Letter SL12-552/HWC
Besides the earlier-mentioned scheduled inspections, some observations of the lubricating oil system can con-
BWM (Bearing Wear Monitoring) suppliers, approved by MAN Diesel & Turbo
veniently be made on a more frequent basis, preferably on Amot
a daily basis:
www.bearingwear.com
A visual vis ual check c heck of an o il sample sa mple for appea a ppearanc rance e and smel smelll
BWM system: XTS-W+
can give early information about deterioration or contamination by particles or water. A detailed description of
Dr. E. Horn GmbH
these checks can be seen in the instruction book.
www.dr-e-horn.de BWM system: BDMS
Most lube oil systems have a lter unit where back ushing will be trigged by high differential pressure over the
Kongsberg Marine
lter. In case of abnormal wear in one of the engine bear-
www.km.kongsberg.com
ings, the back ushing frequency is likely to increase.
BWM system: BWCM
Therefore, Ther efore, f reque nt obser ob ser vation s of th e back ush ushing ing Rovsing Dynamics
frequency are advisable.
www.rovsing-dynamics.com BWM system: OPENpredictor
WIOM (Water In Oil Monitoring) suppliers, approved by MAN Diesel & Turbo
BTM (Bearing Temperature Monitoring) suppliers, recommended by MAN Diesel & Turbo
Kongsberg Maritime AS Kongsberg www.km.kongsberg.com
Kongsberg Marine
WIO monitoring system: MMT330
www.km.kongsberg.com
Dr. E. Horn GmbH
Dr. E. Horn GmbH
www.dr-e-horn.de
www.dr-e-horn.de
WIO monitoring system: FRG00032-2_AW
BTM system: BTMS
Doosan Engine Co. Ltd. Head Ofce & Changwon Plant www.doosanengine.com WIO monitoring system: O-WACS Vaisala Vais ala Oyj Asi Asiaka akaspa spalvel lvel u www.vaisala.com WIO monitoring system: MMT330 E+E Elektronik Ges.m.b.H. www.epluse.com www.ee-elektronik.de WIO monitoring system: EE36 PAJ Systemteknik www.paj.dk WIO monitoring system: WIO 200
Inspection and Monitoring of Crank Train Bearings. Page 4 of 4 pages
