Experiences with ‘Common Rail’

MWD
9th September 2010, 18:03
As an ‘Old Timer’ who sailed (late 50’s and early 60’s) on double acting opposed piston Harland built B&W two strokes, the thought of sailing on today’s vessels having very high pressure heated fuel oil coursing through large diameter common rail fuel lines, coupled with control rooms and unmanned engine spaces, leaves me feeling uneasy, especially as I also understand that statistically, fuel oil leaks are a prominent cause of engine room fires.

So I pose the question to the present and past chief’s and seconds amongst our large community who have experience of these systems, do they pose a heightened threat to the safety of the vessel compared with the earlier and much lower pressure systems?

Or are my concerns unjustified.

MWD.

surfaceblow
9th September 2010, 19:05
The high pressure fuel lines are required to be double walled with flow sensors in the space between the two walls for leak detection and shutting down the oil flow. The low pressure fuel lines are also prone to fuel leaks. The oil pipes including the Lube Oil Lines have covers around the flanges to keep leaks from finding an ignition source. I was on a ship that had a gage line to a differential pressure sensor fail and spray fuel into the turbocharger that caused a nasty fire.

Joe

Don Matheson
9th September 2010, 19:40
MWD, as Joe says pipes today are double walled or pipes inside pipes. These are normally connected to a small tank which will give an alarm if leakage gathers in the tank thus alerting engineers to leakage. The double pipe system tends to stop fuel spraying onto exhaust or other heat sources.
Also like Joe and his sensor, I once had to fly to Goa to oversee the repair of an engine which had had an lub oil pressure sensor sheer, pumping oil onto the exhaust. The turbo sucked the flame into the airside of the engine which overheated an intercooler which burst and in turn flooded the airside of the engine pumping water into the cylinders through head valves. While the engine self destructed the other kept running and the fire got bigger and bigger. The fire was extinguished by an overhead CO2 cylinder exploding as it had failed to operate. So its not all fuel problems as you probably know.

Don

makko
9th September 2010, 20:07
I would say that the fuel system is no more dangerous than in years of yore. If anything, it may even be safer. Good housekeeping has always been the rule.

The greatest benefit of common rail systems is variable timing for the engine and the resultant increase in available power coupled with reduction of emissions.
Rgds.

Dave

cubpilot
9th September 2010, 21:05
With the double wall shielding of today's engines it is probably safer than the good old days of the Doxfords that had a common rail high pressure high temperature fuel supply and no shielding.
I was an apprentice at the time but on one trip we had a very close call for a major fire when a pipe fractured and sprayed a sheet of flaming oil that luckily hit a bulkhead and not into the adjacent purifier room. Quick thinking of those on watch in shutting that engine down prevented a major incident.
There is the question of how long it would take for a fire to take hold versus the time for the duty engineer to get into the engineroom, work out what the alarm is for and then act in the unmanned environment but all round it is safer today

Landi
9th September 2010, 22:16
We have a 900 bar pilot injection system, on the main engines which if it leaks at all, soon loses the pressure and the line low pressure alarm sounds.

My current ship has many fire detection heads of different types, in total we have 330 separate heads in different zones all linked to computer screens which show the alarm zone area and which head has been set off, we also have a double knock system where by if two alarms are set off within a protected zone, a water sprinkler system is set off automatically, this gives fire fighting first aid until the situation can be assessed by a fire party and decisions made on the best next step. The main engine room areas are also covered by cameras which may be of some use at an early stage in any fires development.

The worst fire I have seen at sea was caused by diesel at 3 bar spilling from a fractured 10 mm copper pipe.

Ian

MWD
10th September 2010, 17:40
Thanks for your very interesting responses gents. How things have changed since my days!
The availability of IT and some common sense has obviously very much improved the safety of fuel oil lines.
Am I correct then in assuming the greater power and efficiency is due to the common rail allowing a camshaftless engine with computer controlled variable fuel injection and valve timing?
You also mention improved emissions with common rail. I have heard of more recent engines being smokeless, how does common rail achieve this?
I seem to remember our funnel plume used to look much the same as a steamer and worse when manoeuvring! and that was on marine gas oil!
There seems to be much talk in the newspapers of ever tighter marine emissions, how on earth are the older engine vessels with much useful life remaining ever going to comply? Seems to me the legislators could do with a trip or two at sea before setting the limits.
MWD.

makko
11th September 2010, 04:32
MWD,
You might want to check out the MAN B&W site for their newsletter - Very interesting reading of the "future". In a nutshell the answer to your astute presumption is "when" and "how much"! One of the most interesting projects that I have read about is a 1x heavy fuel oil engine, waste heat to decompose sewage, gas used to drive a 2nd engine, waste heat to drive a steam turbine generator - One "oil engine" and then two "free" engines! After all the bells and whistles have been discussed, it is still very much the same! One note, large 2S engines can develop 2000 Bar during injection! Scary stuff.
Rgds.
Dave

MWD
11th September 2010, 19:14
Thanks Dave,

I will have a look at their site.

From what I have learnt on this site I don't think I should like to be at sea under todays conditions.

I think I belong to the torch, wheel key and shifting spanner brigade. We resolved most problems with this kit or the precision persuader, (large hammer) Heaven knows how many bottom end bolts we stretched beyond their limits.

We had no gas or electric welding gear only a blacksmiths forge, if the storekeeper could find any fuel for it. However we did have a radial drill and shaper as well as a lathe on the larger vessels.

Do tankers still have those horrible bronze hand tools which I found just about useless, as most work seemed to be in confined spaces where due to their bulk, they simply would not fit on the nuts.

Still regard my time at sea with great nostalgia, hence being on this site

Regards,

Mike.

Satanic Mechanic
12th September 2010, 01:41
On slow speed main engines Common rail disappeared for a long time, it just a lot of hassle for little return, each cylinder went back to having their own fuel pump and has already been said the HP side of these are double walled with alarms. One variation though was the VITs system where the injection timing was mechanically varied to engine speed by moving the fuel pump barrel vertically in line with engine revs

However with the advent of electronics and advances in hydraulic controls attention once more turned to the 'camless' engine a few years ago which culminated in the B&W ME series and the Wartisilla(Sulzer) Flex engines. The idea of course that the engines can now have near infinitely variable timing and during sea trials the engines are tuned to an individual performance 'map' to ensure optimum injection timing as well as even cylinder performance across the engine, this also continues onto the exhaust valve timing as well as the CLO injection timing. The CLO thing is a work of wonder as well bringing in specific consumptions as low as 0.5 g/shphr.


Bronze tools continue to be supplied by ship yards as non sparking tools. Modern thinking is that due to their softer nature they have a habit of picking up and embedding small shards of ferrous metals which in turn turns them into very sparky tools. Some ports still demand their use though.

Duncan112
12th September 2010, 10:27
If you can get hold of an ISSA catalogue bronze tools are listed, together with a whole host of other half forgotten / supposedly unobtainable items. My copy (2000) still lists asbestos fibre, and in the recreation section a unicycle - just what you need after a heavy night ashore having sailed into a gale. Apologies for going off thread here.

http://www.shipsupply.org/Pages/catalogues.aspx

Satanic Mechanic
12th September 2010, 10:46
If you can get hold of an ISSA catalogue bronze tools are listed, together with a whole host of other half forgotten / supposedly unobtainable items. My copy (2000) still lists asbestos fibre, and in the recreation section a unicycle - just what you need after a heavy night ashore having sailed into a gale. Apologies for going off thread here.

http://www.shipsupply.org/Pages/catalogues.aspx


Ask a lot of Engineers and they will chew your hand off for asbestos packing and sheets - its still the best stuff around

david freeman
12th September 2010, 11:49
Doxfords Common Rail?

Duncan112
13th September 2010, 07:23
Ask a lot of Engineers and they will chew your hand off for asbestos packing and sheets - its still the best stuff around

Certainly swore by Golden Walkerite on steamships - speaking to Walkers recently they intimated that if still available it would outsell all of the high tech replacements.

What were the compressed asbestos and spring steel ring joints called?

Satanic Mechanic
13th September 2010, 14:04
Certainly swore by Golden Walkerite on steamships - speaking to Walkers recently they intimated that if still available it would outsell all of the high tech replacements.

What were the compressed asbestos and spring steel ring joints called?

Metaflex - good product

Don't tell anyone but if you delve into the deepest darkest recesses of the ship you might just find the 2/Es top secret and jealously guarded asbestos stash for those really important steam jobs (Smoke)

Duncan112
13th September 2010, 17:55
Metaflex - thanks SM, just in case there is any left to be fitted, here is a tip gained from an ex professional 3/E, for the smaller rings, weld a piece if welding wire to the outer reinforcing ring to make it look like a lollipop, this enabled it to be accurately positioned between the two larger flanges - (especially good on the smaller valves to the Bailey flow transmitters - the larger ones would locate accurately on the flange bolts) once positioned and tightened up cut the wire off to stop anyones eye being poked out. Saved me a bundle of time and burnt fingers.

Satanic Mechanic
13th September 2010, 18:12
Metaflex - thanks SM, just in case there is any left to be fitted, here is a tip gained from an ex professional 3/E, for the smaller rings, weld a piece if welding wire to the outer reinforcing ring to make it look like a lollipop, this enabled it to be accurately positioned between the two larger flanges - (especially good on the smaller valves to the Bailey flow transmitters - the larger ones would locate accurately on the flange bolts) once positioned and tightened up cut the wire off to stop anyones eye being poked out. Saved me a bundle of time and burnt fingers.


They are still very much in existance and indeed many with 'tails' just as you describe ready to go, just pop your spanners in a bucket of water and your off.

chadburn
14th September 2010, 12:06
Most Engineer's have "Asbestos finger's" when they could and still can pick up hot items which other's drop. The other side of course is Plural plaques which affect most of us these day's. The super "new" material Carbon Fibre given the right conditions is just as dangerous. In regards to pipework, good bracketing (and plenty of them) was the key.

Satanic Mechanic
14th September 2010, 12:09
To be honest I never really considered asbestos sheet or valve packing as particularly dangerous as it was pretty stable but on the other hand asbestos insulation - wow that was just nasty

chadburn
14th September 2010, 12:41
I would agree SM, Walker's Golden Walkerite and Serpant "A" was indeed very good stuff but of course unfortunatly with steam packing came asbestos insulation.

Frank Moorhouse
21st September 2010, 23:56
Doxfords Common Rail?

YES DOXFORDS STAYED COMMON RAIL TO THE END OF THEIR LIVES. INCIDENTALLY THEY EXPERIMENTED WITH A MEDIUM SPEED ENGINE IN THE LATER SEVENTIES WHICH IS NOW ON DISPLAY AT BEAMISH OPEN AIR MUSEUM COUNTY DURHAM . PS I UNDERSTOOD THAT EXPERIMENT FAILED

Duncan112
22nd September 2010, 00:56
The engine at Beamish is a 3JS58C, Doxfords last gasp at producing an engine to compete in the modern world, (http://www.doxford-engine.com/58js3.htm) it incorporated many of the innovations from the failed medium speed engine that you refer to (the Seahorse) but, sadly the prototype engine appears to have been scrapped and only a film remains. http://www.youtube.com/watch?v=la9hr3D0RDI

I understand the problems with the Seahorse mainly related to the piston ring pack

Winebuff
22nd September 2010, 17:23
The engine at Beamish is a 3JS58C, Doxfords last gasp at producing an engine to compete in the modern world, (http://www.doxford-engine.com/58js3.htm) it incorporated many of the innovations from the failed medium speed engine that you refer to (the Seahorse) but, sadly the prototype engine appears to have been scrapped and only a film remains. http://www.youtube.com/watch?v=la9hr3D0RDI

I understand the problems with the Seahorse mainly related to the piston ring pack

There was also a story about at the time that they were running out of cash for the extended running trials and approached the government for financial support to cover fuel costs etc, were turned down by Maggie and went into receivership shortly thereafter leaving the Germans to come in and pick up the technology for a song.

Billieboy
22nd September 2010, 19:32
I went to the final sale of Doxford at Sunderland, after 8 months 12 days and 17 hours in a fourleg doxford in 1962, it was the happiest day of my life, to see the end of the monsters!

Mike S
23rd September 2010, 02:26
Noo then Biollieboy.......you are talking about the closest thing to perpetual motion engineers ever produced. :D

Satanic Mechanic
23rd September 2010, 02:40
Ah Doxfords now there is a tricky one. You feel you have to say how good they were for fear of being branded a heretic and getting spannered to death (which is like getting stoned but they use spanners - whitworth only of course) but I have to admit every time I look at them I can't actually think of a way to make them more complicated than they were already. When it comes to stonecrushers I'll happily admit to being a MAN B&W guy all the way

Duncan112
23rd September 2010, 03:26
Ah Doxfords now there is a tricky one. You feel you have to say how good they were for fear of being branded a heretic and getting spannered to death (which is like getting stoned but they use spanners - whitworth only of course) but I have to admit every time I look at them I can't actually think of a way to make them more complicated than they were already. When it comes to stonecrushers I'll happily admit to being a MAN B&W guy all the way

Make them double acting like the B&Ws - an extra 4 bearings per unit plus the extra fuel pumps and timing valves

Satanic Mechanic
23rd September 2010, 11:15
Make them double acting like the B&Ws - an extra 4 bearings per unit plus the extra fuel pumps and timing valves

Ok - that lost me:confused:

Billieboy
23rd September 2010, 18:54
Apart from the fact that the engine I was first tripper on, never ran for more than 24 hours, until we got out of dry dock in Japan after running out of fuel and catching fire; on the way home from New Westminster, we were off Nicaragua when we lost all bearings in the crankcase, six days of six on and off, nearly killed the fiver, and I was also very close too! On clean Diesel these engines may have been reasonable, but on HFO with ballast/bunker tank sludge, they weren't very accommodating at all. which is the reason I moved to steam turbines.

eldersuk
23rd September 2010, 23:34
What's all this about Doxfords, sailed with them for years with never a scrap of trouble (Ahem!) best engines ever with a bit of TLC. Once coasted a Bluey with a double acting something or other, ran a mile from that one. So many pistons around the place you could only tell which were the spares when they didn't move when the engine was started. Derek

Duncan112
24th September 2010, 02:18
Here is a link to a video of a double acting opposed piston B&W - for some reason B&W have taken the video off the Dieselhouse site but fortunately there are copies on YouTube

http://www.youtube.com/watch?v=unAsUugK9zw

Satanic Mechanic
24th September 2010, 02:27
Alas and woe - you can't get youtube in china(Cloud)

However I know where your coming from now, just checking is it defo double acting?. MAN also had a single acting opposed piston engine except (if marine engineering history serves me right) it contravened Doxford patents and instead the upper piston wsa redesignated as an exhaust valve and run through eccentrics instead of cranks on the shaft.

n.b. anyone who has a more in depth knowledge of this please feel free to correct me, I am working from hazy memory here(Hippy)

roboted
24th September 2010, 08:15
I think what you are both talking about is the Harland & Wolfe type licence built B&W....Single Acting,Double opposed...Ie One combustion space,two opposing pistons..The Exhaust(top) piston did indeed run of eccentrics either side of the bottom end journal.
Where the confusion appears to have crept in over the years was that B&W also produced a Double acting Triple opposed engine,two combustion spaces,three opposing pistons in the same liner,centre piston running of BE journal and top and bottom pistons running off eccentrics either side of it,

Satanic Mechanic
24th September 2010, 10:46
I think what you are both talking about is the Harland & Wolfe type licence built B&W....Single Acting,Double opposed...Ie One combustion space,two opposing pistons..The Exhaust(top) piston did indeed run of eccentrics either side of the bottom end journal.
Where the confusion appears to have crept in over the years was that B&W also produced a Double acting Triple opposed engine,two combustion spaces,three opposing pistons in the same liner,centre piston running of BE journal and top and bottom pistons running off eccentrics either side of it,

Thats the one I'm thinking of (I meant B&W not MAN - but I'm sure you all knew that(Thumb))

I have heard dark rumours of the other engine but apparantly I'm not old enough to be told the truth about it(Hippy)

cubpilot
24th September 2010, 11:56
Sailed on a load of poorly financed Doxford engine ships but that company also failed to provide proper spares for their other engines too. Hence the dislike for the type. However sailed on one Doxford engined ship in a different company which was cared for by the accountants and we never had a single stoppage in six months.
Weirdest engine I came across was an MAN built about 1946 which had stuffing boxes on the piston rods made from cast iron segments. The size of these had to be matched to the piston rod diameter. We had a fair number of spare rods that were honed true, hence the selection of diameters. Regular stoppages due to seizures where the piston rods could start to glow red. if not caught in time and fuel pump lifted and all on watch squirting oil on the rod it rod could bend and be scrapped. Until the rod cooled down we would have the nagging fear of a crank case explosion, then depending how soon it brought under control it would be a case of gingerly bringing the engine back up to sea speed or a piston change.

chadburn
24th September 2010, 13:01
Sounds like the packing on the "newer" VTE's, were little springs involved in the set up?

roboted
24th September 2010, 16:56
Thats the one I'm thinking of (I meant B&W not MAN - but I'm sure you all knew that(Thumb))

I have heard dark rumours of the other engine but apparantly I'm not old enough to be told the truth about it(Hippy)

I've seen&been inside the crankcase on one.....nightmare/awesome.Take your pick (H)

cubpilot
24th September 2010, 18:24
Sounds like the packing on the "newer" VTE's, were little springs involved in the set up?

yes if memory serves me right. they were a nightmare to build up in situ but if it were a piston change you could bench assemble and drop in place. there was an top stuffing box fitted at the bottom of the cylinder liner and then a less complex box fitted to the top of the crank case structure to prevent crankcase oil flowing upwards, these were about a foot apart and you could view the piston rods in the open space. needless to say we used to wander past as often as possible during a watch.
if these engines were in modern use one wonders how it would be monitored for an unmanned engineroom.