Download 5510-0143-00ppr Low Service Experience PDF

Title5510-0143-00ppr Low Service Experience
TagsTurbocharger Diesel Engine Piston Cylinder (Engine) Wear
File Size5.1 MB
Total Pages32
Document Text Contents
Page 1

Service Experience
Two-stroke Engines

Page 16

16

The reason for the oval wear is found

when looking at the circumferential

temperature distribution in the top of

the cylinder liner measured on the test

bed on the prototype engine. Fig. 26

shows what was measured around the

circumference of the cylinder liner. In

forward and aftward direction, 225ºC

was measured, whereas in exhaust and

manoeuvring direction only 190ºC was

recorded. This gives sufficient protec-

tion against cold corrosion in one direc-

tion, but not in the other direction.

The cylinder liner design of the bore-

cooled type is illustrated in Fig. 25.

Cooling bores in the top of the liner are

evenly distributed around the circumfer-

ence. Pipes are inserted in the cooling

bores in order to distribute water to the

very top of the cooling bores. A version

of these pipes is insulated towards the

liner surface. This will restrict cooling

water closest to the liner surface, and it

will also limit the total amount of water

flowing through each cooling bore.

By inserting insulated cooling pipes in

the cooling bores in exhaust-manoeu-

vring direction, see Fig. 28, we can

increase the temperature on the liner

surface in this direction without chang-

ing the situation in forward-aftward di-

rection.

Cylinder liner wear measurements have

confirmed the above-described change

to be effective against excessive (oval)

liner wear, see Fig. 29. Trend curves on

cylinders with 2 x 5 insulated cooling

pipes are well within acceptable limits.

Case two: S70MC-C7 with high top-

land (HTL)

On a series of 6S70MC-C7 engines,

cylinder liners with 30 cooling bores

were supplied instead of, as specified,

cylinder liners with 24 cooling bores.

This led to excessive cylinder liner wear

caused by cold corrosion attacks in the

upper part of the cylinder liners.

One, in theory, easy countermeas-

ure would be to exchange the cooling

pipes with insulated ones. However, in

practice this is a rather time consum-

ing operation. Therefore, an alternative

more-easy-to-retrofit solution has been

developed for this series of engines in

order to save as much as possible of

the cylinder liner lifetime.

275
°C

250

225

200

175

150

125

100

75

50

1
3
5

Exh.

Exhaust

Fore

Fore

Man.

Manoeuvring

Aft

Aft

Exh.

Point 3 = Top ring TDC position area.
Insulated cooling pipes will increase the running
surface temperatures by 20-40°C.

Fig. 26: S70 Semi-high topland (SHTL): circumferential temperature distribution

Page 17

Service Experience Two-stroke Engines – 2013 17

Fig. 27: S70 semi-high topland (SHTL): cooling bores

Fig. 28: S70 semi-high topland: insulated cooling
pipes

0.1/1000 Hours (mm)
Cyl No. 1A
Cyl No. 2A
Cyl No. 3A
Cyl No. 4A
Cyl No. 4A, test liner, 10 insulated pipes
Cyl No. 5A
Cyl No. 6A
Cyl No. 6A, test liner, 10 insulated pipes

Test liners with
10 insulated cooling pipes

0 2,000

699.5

700.0

700.5

701.0

701.5

702.0

702.5

703.0

4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000

Engine Hours

Liner Wear

M
ax

li
ne

r
D

ia
m

et
er

(m
m

)

Fig. 29: S70 semi-high topland (SHTL): cylinder liner wear

Page 32

MAN Diesel & Turbo
Teglholmsgade 41
2450 Copenhagen SV, Denmark
Phone +45 33 85 11 00
Fax +45 33 85 10 30
[email protected]
www.mandieselturbo.com

MAN Diesel & Turbo – a member of the MAN Group

All data provided in this document is non-binding. This data serves informational
purposes only and is especially not guaranteed in any way. Depending on the
subsequent specific individual projects, the relevant data may be subject to
changes and will be assessed and determined individually for each project. This
will depend on the particular characteristics of each individual project, especially
specific site and operational conditions. Copyright © MAN Diesel & Turbo.
5510-0143-00ppr May 2013 Printed in Denmark

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