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  #1  
Old 14th January 2019, 12:59
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Doxford Reflections

I had thought that the majority of my sea time was spent with LB Doxfords but looking back into my discharge book I realise that was not the case – it just seemed that way ‘cos lots of “stuff” happen during those times!
The Doxford engine, with its uniflow scavenging and constant pressure fuel injection, certainly had the best fuel consumption of its time and, with no combustion loads transmitted to the structure, were relatively vibration free but …… it was so mechanically complicated!
Main bearings was in a spherical pocket, and each unit had two pistons and so many bearings; three bottom end bearings in spherical housings, three crosshead bearings and slippers, two side rod bearings and a big centre bearing in the transverse beam.
Despite this, the engines up to 670mm bore seemed to run quite well but, of course, the number of components resulted in a large maintenance load compared with single piston engines even when they were running well.
For my sins most of my time was spent with 75LB6 engines and because I didn’t know much different I didn’t realise at the time how bad they were. I think there were only 12 of this size built and our company had six of them and I sailed on 4 of those.
Before they were 4 years old, all our engines had to have new crankshafts due to a design defect. However, they still had a weakness in that No 3 forward and No 4 aft crankwebs were highly stressed at the internal fillet with the adjacent main journal. This wasn’t helped by the fact that the ships themselves were very flexible and resulted in having to be careful with crankshaft alignment and I became quite proficient at threading a piano wire through the engine and the aft engine room bulkhead to the aft peak bulkhead. However that didn’t stop us finding a large fracture in No.4 on one ship and having carried out a sort of repair sailed back to the UK to discover another fracture at No3 as the engine was being dismantled to receive it’s third crankshaft in 12 years.
All these engines kept the likes of Andrews Master Hones and Golten Marine in business machining our journals and pins in situ as we had numerous bearing failures. For reasons I can’t remember we has several failures of bottom end bearings resulting from the white metal breaking up like crazy paving. Other failures probably resulted from locked sphericals and dirt and water contaminated lube oil.
Being non-diaphragm engines it was a battle to keep the oil clean, not helped by high piston ring and liner wear rates, so we fitted larger bottom piston scraper drains and run purifiers continuously and injected trisodiumphosphate to decrease the acidity .
Water contamination was a problem because the bottom piston cooling water system, in addition to the usual gland problems, also suffered for severe erosion and despite setting off with lots of elbows and pipes, there never seem to be enough.
As a consequence of dirty, wet oil we ended up with a very severe microbial attack on one ship and a lesser attack on another that resulted in more profits for the in situ machiners and the airlines flying crosshead pins back to the UK for microfinishing.
This size engine also seemed to suffer for disproportionally high were rates with the transverse pin bearings compare with the smaller bore engines. I wonder if this had anything to do with the exceptional flexibility of the crankshaft? We had a good example of this with the engine with the fractured crasnkshaft; a large steel strap has been fitted around the crankweb and we had to cut a bit of the bedplate away to allow it to rotate. However when we started the engine we found the strap was fouling the bedplate despite there being ample clearance in the static condition!
There were many more issues but I don’t remember feeling bad about them – in my ignorance I just thought that was the way of things when you went to sea as an engineer in the '60s. But then I did my “steam time”………….. and my eyes were opened!
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Last edited by Tim Gibbs; 15th January 2019 at 10:58.. Reason: I wanted to DECREASE the acidity !!
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  #2  
Old 14th January 2019, 16:27
OilJiver OilJiver is offline  
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….... But then I did my “steam time”………….. and my eyes were opened!
…..Even in the glare of all those brilliant white boilersuits…..!



(V interesting post btw. Many thanks)

Last edited by OilJiver; 14th January 2019 at 16:29..
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  #3  
Old 17th January 2019, 22:56
sternchallis sternchallis is offline
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…..Even in the glare of all those brilliant white boilersuits…..!



(V interesting post btw. Many thanks)
Not for long though.
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  #4  
Old 18th January 2019, 09:59
saudisid saudisid is offline  
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Originally Posted by Tim Gibbs View Post
I had thought that the majority of my sea time was spent with LB Doxfords but looking back into my discharge book I realise that was not the case – it just seemed that way ‘cos lots of “stuff” happen during those times!
The Doxford engine, with its uniflow scavenging and constant pressure fuel injection, certainly had the best fuel consumption of its time and, with no combustion loads transmitted to the structure, were relatively vibration free but …… it was so mechanically complicated!
Main bearings was in a spherical pocket, and each unit had two pistons and so many bearings; three bottom end bearings in spherical housings, three crosshead bearings and slippers, two side rod bearings and a big centre bearing in the transverse beam.
Despite this, the engines up to 670mm bore seemed to run quite well but, of course, the number of components resulted in a large maintenance load compared with single piston engines even when they were running well.
For my sins most of my time was spent with 75LB6 engines and because I didn’t know much different I didn’t realise at the time how bad they were. I think there were only 12 of this size built and our company had six of them and I sailed on 4 of those.
Before they were 4 years old, all our engines had to have new crankshafts due to a design defect. However, they still had a weakness in that No 3 forward and No 4 aft crankwebs were highly stressed at the internal fillet with the adjacent main journal. This wasn’t helped by the fact that the ships themselves were very flexible and resulted in having to be careful with crankshaft alignment and I became quite proficient at threading a piano wire through the engine and the aft engine room bulkhead to the aft peak bulkhead. However that didn’t stop us finding a large fracture in No.4 on one ship and having carried out a sort of repair sailed back to the UK to discover another fracture at No3 as the engine was being dismantled to receive it’s third crankshaft in 12 years.
All these engines kept the likes of Andrews Master Hones and Golten Marine in business machining our journals and pins in situ as we had numerous bearing failures. For reasons I can’t remember we has several failures of bottom end bearings resulting from the white metal breaking up like crazy paving. Other failures probably resulted from locked sphericals and dirt and water contaminated lube oil.
Being non-diaphragm engines it was a battle to keep the oil clean, not helped by high piston ring and liner wear rates, so we fitted larger bottom piston scraper drains and run purifiers continuously and injected trisodiumphosphate to decrease the acidity .
Water contamination was a problem because the bottom piston cooling water system, in addition to the usual gland problems, also suffered for severe erosion and despite setting off with lots of elbows and pipes, there never seem to be enough.
As a consequence of dirty, wet oil we ended up with a very severe microbial attack on one ship and a lesser attack on another that resulted in more profits for the in situ machiners and the airlines flying crosshead pins back to the UK for microfinishing.
This size engine also seemed to suffer for disproportionally high were rates with the transverse pin bearings compare with the smaller bore engines. I wonder if this had anything to do with the exceptional flexibility of the crankshaft? We had a good example of this with the engine with the fractured crasnkshaft; a large steel strap has been fitted around the crankweb and we had to cut a bit of the bedplate away to allow it to rotate. However when we started the engine we found the strap was fouling the bedplate despite there being ample clearance in the static condition!
There were many more issues but I don’t remember feeling bad about them – in my ignorance I just thought that was the way of things when you went to sea as an engineer in the '60s. But then I did my “steam time”………….. and my eyes were opened!
Tim
Would you be talking about the Ripon class when you say the company had 6.
I did 3 trips as Cadet in the Ripon and first trip Third Mate in her.

Alan
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  #5  
Old 21st January 2019, 17:01
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Tim
Would you be talking about the Ripon class when you say the company had 6.
I did 3 trips as Cadet in the Ripon and first trip Third Mate in her.

Alan
Yes Alan, it was that class and she was my first 75LB6 Doxford. I sailed as Engineer Cadet on her in 1962 (my God , that's over half a century ago!). Apart from a 24 hours stoppage in the Red Sea I don't recall much else about her although I have this silly idea that the GA drawing in the alleyway said the funnel was 49'10" high . Could that possibly be true ?!
Next up was the ' Newcastle, my first 2/E job and not many fond memories of her and certainly none regarding trying to sort out a serious problem with No.4 main bearing prior to her being sold to Ben Line in 1968.
That was soon followed by the fateful trip on the 'Colombo when we found the crankshaft fractured and I subsequently stood-by her in Sunderland whilst the the crankshaft was being replaced.
My first C/E job was the 'Winnipeg of which I have few memories but I have many memories of my last trips to sea - back to the dreaded 'Colombo for a couple Canada - India trips.
The class association didn't end there as I had the 'Colombo & 'Newcastle as two of my ships as a Superintendent. It seems that, like the poor, they are always with you
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Old 21st January 2019, 17:07
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[QUOTE= ..... I think there were only 12 of this size built and our company had six of them and I sailed on 4 of those.....
[/QUOTE]
I'm may be wrong about there being only 12 built as, in addition to the ones I knew about, a friend of my mine told me the other day that he was almost certain NZS had some. Can anyone confirm that ?
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  #7  
Old 6th March 2019, 00:39
csturnbull csturnbull is offline  
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Interesting stuff, takes me back to my Elder Dempster days over fifty years ago, nearly all Doxfords with the odd one or two B&W's. I have just been looking at the old Port Sydney on YouTube but I cannot remember what the small wheel was for on the left of the controls!! Time to book into the Old Peoples Home I think!!
Can anyone refresh an old brain??
Cheers
Cliff
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Old 6th March 2019, 01:43
dannic dannic is offline  
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Originally Posted by csturnbull View Post
Interesting stuff, takes me back to my Elder Dempster days over fifty years ago, nearly all Doxfords with the odd one or two B&W's. I have just been looking at the old Port Sydney on YouTube but I cannot remember what the small wheel was for on the left of the controls!! Time to book into the Old Peoples Home I think!!
Can anyone refresh an old brain??
Cheers
Cliff
Fuel pressure, after starting you had to keep fuel pressure up at 600 psi range.
Dannic.
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Old 6th March 2019, 01:45
dannic dannic is offline  
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Originally Posted by Tim Gibbs View Post
I had thought that the majority of my sea time was spent with LB Doxfords but looking back into my discharge book I realise that was not the case – it just seemed that way ‘cos lots of “stuff” happen during those times!
The Doxford engine, with its uniflow scavenging and constant pressure fuel injection, certainly had the best fuel consumption of its time and, with no combustion loads transmitted to the structure, were relatively vibration free but …… it was so mechanically complicated!
Main bearings was in a spherical pocket, and each unit had two pistons and so many bearings; three bottom end bearings in spherical housings, three crosshead bearings and slippers, two side rod bearings and a big centre bearing in the transverse beam.
Despite this, the engines up to 670mm bore seemed to run quite well but, of course, the number of components resulted in a large maintenance load compared with single piston engines even when they were running well.
For my sins most of my time was spent with 75LB6 engines and because I didn’t know much different I didn’t realise at the time how bad they were. I think there were only 12 of this size built and our company had six of them and I sailed on 4 of those.
Before they were 4 years old, all our engines had to have new crankshafts due to a design defect. However, they still had a weakness in that No 3 forward and No 4 aft crankwebs were highly stressed at the internal fillet with the adjacent main journal. This wasn’t helped by the fact that the ships themselves were very flexible and resulted in having to be careful with crankshaft alignment and I became quite proficient at threading a piano wire through the engine and the aft engine room bulkhead to the aft peak bulkhead. However that didn’t stop us finding a large fracture in No.4 on one ship and having carried out a sort of repair sailed back to the UK to discover another fracture at No3 as the engine was being dismantled to receive it’s third crankshaft in 12 years.
All these engines kept the likes of Andrews Master Hones and Golten Marine in business machining our journals and pins in situ as we had numerous bearing failures. For reasons I can’t remember we has several failures of bottom end bearings resulting from the white metal breaking up like crazy paving. Other failures probably resulted from locked sphericals and dirt and water contaminated lube oil.
Being non-diaphragm engines it was a battle to keep the oil clean, not helped by high piston ring and liner wear rates, so we fitted larger bottom piston scraper drains and run purifiers continuously and injected trisodiumphosphate to decrease the acidity .
Water contamination was a problem because the bottom piston cooling water system, in addition to the usual gland problems, also suffered for severe erosion and despite setting off with lots of elbows and pipes, there never seem to be enough.
As a consequence of dirty, wet oil we ended up with a very severe microbial attack on one ship and a lesser attack on another that resulted in more profits for the in situ machiners and the airlines flying crosshead pins back to the UK for microfinishing.
This size engine also seemed to suffer for disproportionally high were rates with the transverse pin bearings compare with the smaller bore engines. I wonder if this had anything to do with the exceptional flexibility of the crankshaft? We had a good example of this with the engine with the fractured crasnkshaft; a large steel strap has been fitted around the crankweb and we had to cut a bit of the bedplate away to allow it to rotate. However when we started the engine we found the strap was fouling the bedplate despite there being ample clearance in the static condition!
There were many more issues but I don’t remember feeling bad about them – in my ignorance I just thought that was the way of things when you went to sea as an engineer in the '60s. But then I did my “steam time”………….. and my eyes were opened!
Trisodiumphosphate? we used that as cooling water treatment!!
Dannic.
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  #10  
Old 6th March 2019, 05:23
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Trisodium phosphate , a strong alkaline has many uses , even in some food stuffs , but we used it at Babcock as a initial boil out additive to the boiler water when first firing after construction to ensure all heat exchange surfaces were absolutely clear of any contamination especially grease and oil etc .
Came the day when we were commissions a new packaged Steambloc fire tube boiler at the Air New Zealand workshops at Auckland airport.
The burner cut out had been set to shut off the fire at just above 50 lbs/sq inch
But the fact was that the steam safety valve, normally tested and set at 155 Psi was slackened back to about 45 psi.
Bang off she went spraying highly corrosive steam and water over the staff car park. Thank God for an easterly wind , had it been a prevailing westerly we would have doused a whole Douglas DC10 over its aluminium hull which might have desolved before our eyes.
Insurance covered us but the payout was huge as every man and his dog made a claim for even the slightest damage to their cars,
The one I fell sorry for was the young typist with a brand new pumpkin coloured Fiat 500, the body work paint was right off.
Well Off thread but a memory brought on by Doxford stories!

Bob
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Old 6th March 2019, 07:50
Engine Serang Engine Serang is offline  
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Fuel pressure, after starting you had to keep fuel pressure up at 600 psi range.
Dannic.
I have a recollection that on the Regent Falcon it was 6000 psi.

Perhaps I should also check out an old Peoples Home.
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  #12  
Old 6th March 2019, 10:02
csturnbull csturnbull is offline  
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Of course!! Easy when someone tells you!! Many thanks.
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Old 6th March 2019, 10:11
csturnbull csturnbull is offline  
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I have a recollection that on the Regent Falcon it was 6000 psi.

Perhaps I should also check out an old Peoples Home.
Maybe it was 6000psi. I know the start air was 600psi. Racking the old grey matter once again!!
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Old 6th March 2019, 12:17
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Trisodiumphosphate? we used that as cooling water treatment!!
Dannic.
Interestingly, we also found that the TSP injection considerably increase the amount of crap removed by the centrifuges
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Old 6th March 2019, 17:51
sternchallis sternchallis is offline
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Trisodium phosphate , a strong alkaline has many uses , even in some food stuffs , but we used it at Babcock as a initial boil out additive to the boiler water when first firing after construction to ensure all heat exchange surfaces were absolutely clear of any contamination especially grease and oil etc .
The one I fell sorry for was the young typist with a brand new pumpkin coloured Fiat 500, the body work paint was right off.

Bob
As Sub Ltn't Phillips would have said, " Oooooo Narsty" ' Left hand down a bit '.

Just looked up in my copy of Southern's Marine Oil Engines,
during manoevring keep pressure at 6000lb/ in 2, never let fall below 4000 psi.

That TSP gave a yellow tinge to the cooling water on our ships.
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Old 7th March 2019, 10:29
Brian Dobbie Brian Dobbie is offline  
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I seem to remember the mechanical fuel injectors, the type with the cage over the nozzle assembly.
They would regularly jam open when the engine was stopped and fuel pressure 6000psi to zero instantly. Then an Engineer running round the middles with the fork to close and isolate the defective injector. Sometimes the relief valve would lift at next start due to fuel in the cylinder.
All in all not my favourite engine.
My last ship was a Wartsila Rt.Flex and they have gone to common rail with a large fuel accumulator but no priming pump.
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Old 7th March 2019, 11:21
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Was the yellow stuff not Potassium Chromate? IIRC you were not meant to use it in systems with a jacket evaporator for potable water as it was poisonous. I only used Nitrate based ones, but the Chromate was also used as an indicator in Nitrate titrations for Chloride contamination.
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Old 7th March 2019, 13:46
sternchallis sternchallis is offline
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Originally Posted by Brian Dobbie View Post
I seem to remember the mechanical fuel injectors, the type with the cage over the nozzle assembly.
They would regularly jam open when the engine was stopped and fuel pressure 6000psi to zero instantly. Then an Engineer running round the middles with the fork to close and isolate the defective injector. Sometimes the relief valve would lift at next start due to fuel in the cylinder.
All in all not my favourite engine.
My last ship was a Wartsila Rt.Flex and they have gone to common rail with a large fuel accumulator but no priming pump.
Would that be AB Dobbie, known for scooping up 45 gallon of HFO and pouring it down a fuel vent, that suddenly appeared overnight as deck cargo on a former Strick Line ship known for these antics because of a design fault, circa 1982.
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Old 7th March 2019, 14:00
sternchallis sternchallis is offline
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Potassium Chromate , sounds familiar as well, could well have been that. Nasty stuff. The slight leaks at pump glands would crystalise to a white greenish deposit due to the copper parts in the system.

Did anybody use that Shell oil like cutting fluid used in cooling systems that when mixed with lube oil turned to a grey sludge when coming out the LOP. I was on an MAN 1956 vintage that used it.
Flying Bedsteads had the best idea, oil cooled top and bottom pistons on telescopics, any leak into the crankcase didn't matter.
The slight downside was in high sea temps you needed both oil pumps on to increase circulation, but no big deal.
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Old 7th March 2019, 14:47
Brian Dobbie Brian Dobbie is offline  
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Would that be AB Dobbie, known for scooping up 45 gallon of HFO and pouring it down a fuel vent, that suddenly appeared overnight as deck cargo on a former Strick Line ship known for these antics because of a design fault, circa 1982.
Former Strick Line ship???
Fuel oil on deck??? unheard off.
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Old 7th March 2019, 22:53
dannic dannic is offline  
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Originally Posted by Engine Serang View Post
I have a recollection that on the Regent Falcon it was 6000 psi.

Perhaps I should also check out an old Peoples Home.
Sorry and yes you are correct, remember getting a kick in the backside when changing over fuel return cock to day tanks - dont you realise what the pressure in that pipe is??
Dannic.
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Old 7th March 2019, 23:22
OilJiver OilJiver is offline  
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...Fuel oil on deck??? unheard off.
Quite right!

But plenty HFO available (now and then) around the middles (and below) when one of those 6000psi pipes split..
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Old 7th March 2019, 23:54
pitcrew pitcrew is offline
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High pressure plant

After I left the merchant navy I got a job as a mechanical fitter, with Union Carbide, in a low density polyethylene plant.
At the interview the chief maintenance engineer asked if I had any experience working with high pressure.
At the same time as I said yes he said you won’t have.
What pressures have you worked with? He said. I’ve worked on Doxford fuel gear of 6,000 psi says I. And we tested at 12,000 psi.
Well we work at reactor pressures of 38,000 psi, we test at 75,000 psi and we auto fret at 120,000 psi.
I thought he was letting numbers run away with him but he wasn’t, it was frightening the pressures we worked at but the wages were great and I spent 15 years there. After a period of time they dropped the reactor pressure to 32,000 psi because the plant was wearing on a bit.
The ethylene came into the plant at 5 psi, through reciprocating compressors up to 195 psi, 195 to 550 psi then through a rotary compressor before going into what they called an intensifier which was a huge ram pump, four of them to each reactor.
The big money polyethylene went all over the world for the sheathing on sub sea telephone cable and fetched a tremendous price back in the day. Satellites put an end to that earner so Union Carbide pulled out and BP took over with high density polyethylene but at a much lower pressure.
Auto fretting involved hydraulically pressurising the reactor tubes, which came from the USA, so that they stretched before they were installed in the reactors.
Occasionally things went wrong.When ethylene at 38,000 psi catches fire it’s a sight to behold! Squeaky bum time.

Regards,
Pitcrew.

Last edited by pitcrew; 7th March 2019 at 23:56..
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Old 8th March 2019, 11:53
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Did anybody use that Shell oil like cutting fluid used in cooling systems that when mixed with lube oil turned to a grey sludge when coming out the LOP.
Unfortunately, yes on P&OCL's MAN KZs, if you put too much in the header tank at once, it boiled over, but a handful of Epsom Salts sorted it. One voyage the "Horses Head" that carried the coolant to the X Head fell off, the sump resembled Bailey's Irish Cream.

Used a refractometer to check the concentration, and the "Speedy Tester" to find out how bad the sump water contamination was, any less than 5% was a cause for rejoicing.
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Old 8th March 2019, 13:16
OilJiver OilJiver is offline  
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…..At the interview the chief maintenance engineer asked if I had any experience working with high pressure...

Well you got the job Pitcrew so your Doxford knowledge must have impressed! (Or maybe he recognised that you could work under much pressure).

Hairy stuff you describe for sure. Thanks for interesting post.
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