I sure by now most of us have  looked at http://people.bath.ac.uk/ccsshb/12cyl/

I was looking at some documentation on the engine builders site and
came across this:
". The cylinder liner wear rates are in the region of 0.02–0.03 mm/
1000 hours maximum."

in the document:
http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publications/marine_news/2000_3/rta96c_powerful_success.pdf

That equates to about 1 thou in 42 days - I don't now much about
internal combustion engines but that seems quite high. Is it because
of the large bore of the cylinders that the rings can cope with a
relatively large amount of cylinder and ring wear ?

Regards
Tim

"Tim Nash (aka TMN)"  wrote in message 
news:c269902c-b5e6-4fc2-bc84-2dd9cb3ab3f9@k37g2000hsf.googlegroups.com...
I sure by now most of us have  looked at 
http://people.bath.ac.uk/ccsshb/12cyl/

I was looking at some documentation on the engine builders site and
came across this:
". The cylinder liner wear rates are in the region of 0.02–0.03 mm/
1000 hours maximum."

in the document:
http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publications/marine_news/2000_3/rta96c_powerful_success.pdf

That equates to about 1 thou in 42 days - I don't now much about
internal combustion engines but that seems quite high. Is it because
of the large bore of the cylinders that the rings can cope with a
relatively large amount of cylinder and ring wear ?

Regards
Tim


You've got to take it in proportion to bore size though.
For example -
1 thou on a 3" bore is equivalent to 0.0003% wear
1 thou on a 3' bore is equivalent to 0.000025% wear

moray

Tim Nash (aka TMN) wrote:
> I sure by now most of us have  looked at
> http://people.bath.ac.uk/ccsshb/12cyl/
>
> I was looking at some documentation on the engine builders site and
> came across this:
> ". The cylinder liner wear rates are in the region of 0.02-0.03 mm/
> 1000 hours maximum."
>
> in the document:
> http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publications/marine_news/2000_3/rta96c_powerful_success.pdf
>
> That equates to about 1 thou in 42 days - I don't now much about
> internal combustion engines but that seems quite high. Is it because
> of the large bore of the cylinders that the rings can cope with a
> relatively large amount of cylinder and ring wear ?

If you take 85mm as being the average bore of a car engine and 3 thou as a 
reasonable bore wear limit before reconditioning then you get 33 thou wear 
limit or 33,000 hours running for the 965mm bore of the Sulzer. That equates 
to 3.7 years continuous running and container ships need to spend some time 
loading and unloading so probably over 4 years actual service. Well within 
their target of rebuilds every 2 to 3 years.

Compared to a car engine that's a very low rate of wear. Even a well looked 
after car engine is unlikely to see more than 5000 hours service. The Sulzer 
will undoubtedly have much better oil and air filtration systems than car 
engines do though. Most car engine wear is caused by what gets past the air 
filter or doesn't get removed from the oil. Truck engines with 500,000 mile 
service lives also use much better filtration systems than cars.
-- 
Dave Baker 


** Posted from http://www.teranews.com **

On Jul 20, 10:51 am, "Dave Baker"  wrote:
> Tim Nash (aka TMN) wrote:
>
> > I sure by now most of us have  looked at
> >http://people.bath.ac.uk/ccsshb/12cyl/
>
> > I was looking at some documentation on the engine builders site and
> > came across this:
> > ". The cylinder liner wear rates are in the region of 0.02-0.03 mm/
> > 1000 hours maximum."
>
> > in the document:
> >http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publ...
>
> > That equates to about 1 thou in 42 days - I don't now much about
> > internal combustion engines but that seems quite high. Is it because
> > of the large bore of the cylinders that the rings can cope with a
> > relatively large amount of cylinder and ring wear ?
>
> If you take 85mm as being the average bore of a car engine and 3 thou as a
> reasonable bore wear limit before reconditioning then you get 33 thou wear
> limit or 33,000 hours running for the 965mm bore of the Sulzer. That equates
> to 3.7 years continuous running and container ships need to spend some time
> loading and unloading so probably over 4 years actual service. Well within
> their target of rebuilds every 2 to 3 years.
>
> Compared to a car engine that's a very low rate of wear. Even a well looked
> after car engine is unlikely to see more than 5000 hours service. The Sulzer
> will undoubtedly have much better oil and air filtration systems than car
> engines do though. Most car engine wear is caused by what gets past the air
> filter or doesn't get removed from the oil. Truck engines with 500,000 mile
> service lives also use much better filtration systems than cars.
> --
> Dave Baker
>
> ** Posted fromhttp://www.teranews.com**

Dave Baker said:

"4 years actual service. Well within
their target of rebuilds every 2 to 3 years."

OK - the figures make sense then - I thought that such a massive
engine would only be rebuilt every 10 years or so - but that was
a totally subjective figure. Guess I thought when you spend so much
money you don't have to worry about it for a long time !!! But seen in
light of the profits they must make its probably doesn't work out too
badly.

Tim

On 20 Jul, 09:00, "Tim Nash (aka TMN)"  wrote:
> I sure by now most of us have  looked athttp://people.bath.ac.uk/ccsshb/12cyl/
>
> I was looking at some documentation on the engine builders site and
> came across this:
> ". The cylinder liner wear rates are in the region of 0.02–0.03 mm/
> 1000 hours maximum."
>
> in the document:http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publ...
>
> That equates to about 1 thou in 42 days - I don't now much about
> internal combustion engines but that seems quite high. Is it because
> of the large bore of the cylinders that the rings can cope with a
> relatively large amount of cylinder and ring wear ?
>
> Regards
> Tim

You have to remember that you are linear, squares and cubes.

10 times a "reference" engine size =..

10 times the bore and stroke
100 times the area
1000 times the volume

so the ratio of volume (cumbustion charge) is cubed, the area on the
piston is squared but all that torque (which works against the barrel,
therefore barrel / ring / piston wear as quoted, is linear... to some
extent this is countered by lower rpm, but lower rpm is somewhat
countered by longer stroke so mean piston speed isn't that low.

that 5.6 million pound feet is all working against the barrel / ring /
piston every power stroke so the wear figure given is actually more
than merely good.

0.02mm per 1000 hours is 50k hours per mm wear which is 5.7 years, and
1mm wear isn't going to stop that engine running, go work out the
coefficients of expansion of a piston that size from ambient (cold
start) to operating temp.

0.02 mm per 1000 hours really is, as the saying goes, something to
write home about.

In article <c61ffa41-e657-4ee7-a844-0a977c66614b@t54g2000hsg.googlegroup
s.com>, Tim Nash (aka TMN)  writes

>"4 years actual service. Well within
>their target of rebuilds every 2 to 3 years."
>
>OK - the figures make sense then - I thought that such a massive
>engine would only be rebuilt every 10 years or so - but that was
>a totally subjective figure. Guess I thought when you spend so much
>money you don't have to worry about it for a long time !!! But seen in
>light of the profits they must make its probably doesn't work out too
>badly.

Ten to twelve years is approaching the design service life of very large
commercial ships (maybe 15 at a push).  They are build with multiple
redundant systems.  Each system has a few years life.  As systems fail,
backups are switched on - the original and subsequent failed systems are
left by-passed and switched off.  No major component or system that
would cost mega-money and/or take the ship of the water is planned for
by it's original owner.

These types of engines are capable of being run with entire cylinders
not working, pistons missing, parts out for replacement etc, in a way
impossible for smaller engines.  Also, there will be no reduction
gearbox to the propeller.  Direct drive at propellor revs.  Going in
reverse means stopping the engine and starting in the opposite
direction.  No parts to wear out :)

When the ship is no longer viable to a first-world company, it is then
sold to a flag of convenience country and operated for the next X years
with very little, if no servicing done.

After 30/40 odd years use, on rejection as a rust-bucket by its tenth,
3rd World operator, the ship is in prime condition to be bought and
operated by a Greek shipping magnate.....................

Sometimes ships that touch our shores are served a writ.  Basically they
must be serviced to a suitable standard before they move another inch.
The usual result is the captain, crew and vessel are abandoned by the
owners.  It happens... and more than you think.............
 
John
-- 
JC Morrice
john@pentode.demon.co.uk

JC Morrice wrote:

> Sometimes ships that touch our shores are served a writ.  Basically they
> must be serviced to a suitable standard before they move another inch.
> The usual result is the captain, crew and vessel are abandoned by the
> owners.  It happens... and more than you think.............
>  
> John

  prolly more often now, what with the price of scrap steel ...

In message 
, 
"Tim Nash (aka TMN)"  writes
>I sure by now most of us have  looked at http://people.bath.ac.uk/ccsshb/12cyl/
>
Having built this splendid piece of engineering - how do they transport 
it to the vessel.  The background to the pictures does not seem to 
indicate that they are building it in situ.   Dismantle it and take it 
piece by piece perhaps?

Mike



-- 
Mike Whittome

JC Morrice wrote:

> Going in
> reverse means stopping the engine and starting in the opposite
> direction.  No parts to wear out :)

Why don't they just wrap a big bungie cord round the output shaft,  then when 
the cord tightens enough to stop the engine it would restart automatically in 
the other direction ?

-- 
Boo

"Boo"  wrote in message 
news:g6043g$rr5$1$8302bc10@news.demon.co.uk...
> JC Morrice wrote:
>
>> Going in
>> reverse means stopping the engine and starting in the opposite
>> direction.  No parts to wear out :)
>
> Why don't they just wrap a big bungie cord round the output shaft,  then 
> when the cord tightens enough to stop the engine it would restart 
> automatically in the other direction ?
>
> -- 
> Boo
Basically, they do. Except that they commonly use an air compressor and tank 
instead of a bungee cord.

Don Young

Dave Baker wrote:
> Tim Nash (aka TMN) wrote:
> 
>>I sure by now most of us have  looked at
>>http://people.bath.ac.uk/ccsshb/12cyl/
>>
>>I was looking at some documentation on the engine builders site and
>>came across this:
>>". The cylinder liner wear rates are in the region of 0.02-0.03 mm/
>>1000 hours maximum."
>>
>>in the document:
>>http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publications/marine_news/2000_3/rta96c_powerful_success.pdf
>>
>>That equates to about 1 thou in 42 days - I don't now much about
>>internal combustion engines but that seems quite high. Is it because
>>of the large bore of the cylinders that the rings can cope with a
>>relatively large amount of cylinder and ring wear ?
> 
> 
> If you take 85mm as being the average bore of a car engine and 3 thou as a 
> reasonable bore wear limit before reconditioning then you get 33 thou wear 
> limit or 33,000 hours running for the 965mm bore of the Sulzer. That equates 
> to 3.7 years continuous running and container ships need to spend some time 
> loading and unloading so probably over 4 years actual service. Well within 
> their target of rebuilds every 2 to 3 years.
> 
> Compared to a car engine that's a very low rate of wear. Even a well looked 
> after car engine is unlikely to see more than 5000 hours service. The Sulzer 
> will undoubtedly have much better oil and air filtration systems than car 
> engines do though. Most car engine wear is caused by what gets past the air 
> filter or doesn't get removed from the oil. Truck engines with 500,000 mile 
> service lives also use much better filtration systems than cars.

It's also my understanding that these engines have an oil pump driven by 
an electric motor, which is in turn driven by their auxiliary generator. 
So they can switch on the oil supply before they start the engine, and 
greatly reduce the wear which occurs at starting.

Best wishes,

Chris

> Basically, they do. Except that they commonly use an air compressor and tank 
> instead of a bungee cord.


I suppose that does boil down to the same basic principle.  I like my idea 
better though :-)

-- 
Boo