© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
Piston Cooling Insert
3333420.2006.04.05 (2300/SBJ) © MAN Diesel A/S 2006/09/09
TEMP. ON GAS SIDE LOWER 20 C
3333293.2005.01.18 (2500/MCJ) © MAN Diesel A/S 2006/09/09
NEW STYLE PISTON
© MAN Diesel A/S 2006/09/09
MAXIMUM MEASURED COMBUSTION
CHAMBER TEMPERATURES
436 639 567 394
392 379
465
185 198
225 196
© MAN Diesel A/S 2006/09/09
COMBUSTION CHAMBER
Narrow combustion Large combustion
volume volume
© MAN Diesel A/S 2006/09/09
HEAT LOAD ON PISTON
Previous piston design Oros piston design
© MAN Diesel A/S 2006/09/09
Gas Temperature 18 ms After
Start of Fuel Injection
Gas Temperature 18 ms After
Start of Fuel Injection
Temperature
deg. Cel.
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
Original combustion chamber New combustion chamber
© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
CYLINDER CONDITION
© MAN Diesel A/S 2006/09/09
CYLINDER CONDITION
© MAN Diesel A/S 2006/09/09
7S80MC
Running hours: 5,098
© MAN Diesel A/S 2006/09/09
Upper ring groove worn out
K90MC
6831
Running
Hours
© MAN Diesel A/S 2006/09/09
Wear Traces in Chromium Layer
Radial direction
Micro crack pattern in Cr layer (225x) SEM photo (157x)
Detail (780x) Detail (780x)
© MAN Diesel A/S 2006/09/09
PISTON PROBLEM
© MAN Diesel A/S 2006/09/09
PISTON PROBLEM
Ghent, July 2005 H. Rolsted © MAN Diesel A/S 2006/09/09
Cylinder Condition
© MAN Diesel A/S 2006/09/09
????
© MAN Diesel A/S 2006/09/09
Oros Piston and Piston Ring
Ring pack
1st ring: Type: CPR
with Alu-Coat
High
2nd ring: Type: RM5, oblique cut
with Alu-Coat
Low
3rd ring: Type: RM5, oblique cut
with Alu-Coat
Low
4th ring: Type: RM5, oblique cut
with Alu-Coat
Low
© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
Ruined piston ring surface.
© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
Scuffing Characteristics:
Metal to metal contact due to oil film
disturbances
Welding/tearing off of materials from both
liner & piston rings
Wear pattern of liner: All running surface,
TDC and BDC wear ridges
Piston ring grooves are typically worn out
more quickly as well
Wear rate: Total wear out within days
© MAN Diesel A/S 2006/09/09
6S90MC ~ 8.300 Hours
© MAN Diesel A/S 2006/09/09
ALCU COATED CPR RING
© MAN Diesel A/S 2006/09/09
Piston Rings
Broken K98 piston ring,
original type
Piston crown on K98MC-C
Broken top ring, 2nd and 3rd
ring collapsed
© MAN Diesel A/S 2006/09/09
Orginal CL Groove Locations
Predominant breakage location
© MAN Diesel A/S 2006/09/09
Service Experience
Stress concentration (bending),
left 2 mm CL groove: 100%,
right 3 mm CL groove: 72%
Result of fatigue testing: Relative safety factors
Original type: 1.0 (100%)
E-type: 1.4 (140%)
E4-type: 2.1 (210%)
© MAN Diesel A/S 2006/09/09
ABRASIVE WEAR
Status Problem
Cat fines in fuel:
Severe wear of liners
Severe wear of rings
Wear out of CL-grooves
Scuffing
© MAN Diesel A/S 2006/09/09
ABRASIVE WEAR
Status
Cat-fines embedded in piston ring
running surface
© MAN Diesel A/S 2006/09/09
© MAN Diesel A/S 2006/09/09
Piston Ring with ‘White Layer’
Status
3333685.2006.03.25 (2300/SBJ) © MAN Diesel A/S 2006/09/09
TIME FOR OVERHAUL
© MAN Diesel A/S 2006/09/09
TIME FOR OVERHAUL
© MAN Diesel A/S 2006/09/09
TIME FOR OVERHAUL
© MAN Diesel A/S 2006/09/09
5 year's TBO on Large Bore Engines
Backed up by the service experience?
K98MC
First time overhaul unit
1 at 42,250 hours.
Note, still very good
piston ring condition
© MAN Diesel A/S 2006/09/09
5 year's TBO on Large Bore Engines
Backed up by the service experience?
10K90MC-C
45,975 hours
since previous
overhaul. Top-
piston ring PM2+
Ni-Gr
(58,500 engine hours)
© MAN Diesel A/S 2006/09/09
5 year's TBO on Large Bore Engines
Backed up by the service experience?
10K90MC-C
45,975 hours
since previous
overhaul. Top-
piston ring PM2+
Ni-Gr
(58,500 engine hours)
© MAN Diesel A/S 2006/09/09
