Marine Engineering - Practical Tips & Tricks

A place to exchanges questions and ideas of a technical / procedural nature. Go ahead, try to stomp us !
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JK
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Re: Tips & Tricks

Postby JK » Fri May 07, 2010 1:46 am

I think in that case, the tube just happened to be in the workshop when we went looking for glass. Being engineers, we took what was at hand.
It grinds down the surfaces fast, but there is work to do with a regular grinding compound to smooth the surface out.

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Big Pete
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Re: Tips & Tricks

Postby Big Pete » Fri May 07, 2010 6:23 am

One thing I have seen shipyard fitters doing is to stick pieces of self adhesive non slip decking to ships side valve lids to grind them in!!

I DO NOT RECCOMEND THIS

It removes a lot of metal quickly and leaves a bright finish but because the self adhesive sheets are thick the valve lid does not conform to the valve seat and will probably still leak. Possibly O.K. for a first grind on a badly worn valve but not much else.

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JK
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Re: Tips & Tricks

Postby JK » Sat May 08, 2010 1:29 am

A what-not -to do.
Drew Chemicals, in the early 90s, had a product for cleaning and deodorizing drains. This stuff was really good, we used it once a week on one of ships, especially in the galley for a drain that was forever plugging up and odor control.
I was sent to another vessel as standby engineer.
She was crewless, waiting for a docking.
(you can't believe how the noise echos through a empty ship at night, when there are only 4 of you onboard, very eerie)

As things go, the drain traps started to dry out and the ship started to stink. Fortuitously, my old ship tied up beside us and I went over and begged a bottle of this drain product. I followed directions to the letter and put this in every drain on the ship. I felt pretty good about it and the ship smelled immensely better.
Eventually, a dock was arranged and the crew arrived back to get the ship ready. I had the night off and left, leaving the ship in my very capable relief's hands.
I get back early the next morning to be greeted by him at the gangway. He looked shattered.

Of course when everyone rolled onboard, they all went for a shower. The Drew product had been sitting for weeks and as the ship rolled gently at the dock had probably made it's way into the lines. When 20 men arrived and showered, every bit of gunk simultaneously made it's way to the only horizontal line in the system and plugged it solid for 30 feet. They had to take the 6" pipe down and ram round bar through the gunk, to clear it out. Meanwhile the sewage system was completely shut down. You don't realize how essential this system is until it is out of service, eh?

I had a good chuckle, but once I realized what had happened, decided that discretion was the best part of valor.

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The Dieselduck
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Re: Tips & Tricks

Postby The Dieselduck » Tue May 18, 2010 9:54 am

One guy I see every once in a while keeps reminding me of the time we started a very stubborn diesel, a Detroit, perhaps a Cat, but it was cold and damp and I forget other details. He was impressed because I had used a cutting torch to help start it. WHAT the hell !! you say.

Well it works like this, you just get the torch fired up and smoke free, aim it pretty much down the intake of the engine's blower or turbo charger, and turn the engine over. The heat from the torch help heat up the air for compression and voila ! the engine starts without that dangerous ether. Works with glow plugs or not. You should remove air filter first, and if your engine is an oily mess, please don't say "you saw it on dieselduck.net" to your insurance adjuster.

Obviously, your not looking to melt or weld parts here, just a quick little heat down its throat, just like a nice hot cup of coffee/tea on a cold night or early morning.
Martin Leduc
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Martin's Marine Engineering Page
http://www.dieselduck.net

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Big Pete
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Re: Tips & Tricks

Postby Big Pete » Tue May 18, 2010 1:08 pm

In the old days, there used to be lots of air cooled Lister diesels Engines in ship's lifeboats, some of these were fitted with an oil cylinder & plunger to manually inject L.O. into the air inlet manifold to improve cold starting. The oil went through to the cylinder and coated the piston crown, improving the sealing of the piston rings and slightly reducing the clearance volume, and hence increasing the compression ratio. End result higher compression temperature and pressure and ignition!!

Another tip, for cold weather starting, and this was from the Lister Manual, I hasten to add, was to dilute the crankcase oil with Gas oil to lower the viscous drag!! and hence increase the cranking speed ( hand cranked starting in those days.)


One ship I sailed on, the crew had been using ether sprays to start both lifeboat engines (Listers) for years.
When I investigated I found that the fuel lift /priming pumps had a filter built into them and the filter chambers on both engines were blocked solid with sludge. From studying the Engine manual I also found out that there was a small button on the front of the engine, that was supposed to be pressed, to inject extra fuel into the engine during starting, no one onboard new about the magic button.
Subsequently I was able to throw the ether away.


I have also read, in a novel I hasten to add, of someone removing the air filter from an engine and tossing a burning rag into the air intake to get a recalcitrant engine to start. Basically the same idea as Martin's, I haven't tried that one, but I suppose it depends how desperate you are to get the engine started.....

BP
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Re: Tips & Tricks

Postby JK » Thu May 20, 2010 12:33 am

I just received the following sales email:
RYDLYME Marine is a safe biodegradable marine scale remover developed to dissolve problematic fouling mediums including calcium, rust, zebra mussels, barnacles, tiger shells and other mineral deposits that hinder the performance of vital water systems.
This safe and simple solution effectively dissolves rock-like scale deposits that contaminate your water-cooled marine equipment.

w w w . r y d l y m e m a r i n e . c o m
(630) 820-8888
Apex Engineering Products Division
1241 Shoreline Drive
Aurora, IL 60504
An ISO 9001:2008 Certified Company


We have used it on one of our ships and the Chief engineer was suitably impressed at how sucessful the cleaning was.

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Big Pete
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Re: Tips & Tricks

Postby Big Pete » Tue Jun 15, 2010 2:20 am

I recently joined a Passenger RoRo Ferry as a temporary relief Second Engineer. I only had a few minutes handover with my Eastern European predecessor, during which time he informed me that none of the oil mist detectors on the 4 medium speed main engines were working, because the main air compressors were worn and oil was passing through into the compressed air system.

On investigating further I found that the Oil Mist Detectors were made by Schalter Automation. In this type 7 bar air goes through a sintered filter, a variable orifice to limit the air flow, a pressure reducing valve and then into an eductor/ejector/venturi and then vents through a drain to the bilge. ( The makers call this an air pump, which is perhaps not the best translation into English)
The venturi creates a vacuum at its narrowest point (in accordance with Bernoulli's Theorem & the "Steady Flow Energy Equation"), this is connected to the oulet of the oil mist sensor housing and draws air from it, creating a partial vacuum inside which in turn draws air from the crankcase into the sensor chamber.

It is therefore totally impossible for oil, water or any other contamination in the air supply to effect the readings. Also, in this case the hinged covers on all the detector housings had been left open, for reasons unknown!!!!

YOU SHOULD ALWAYS AVOID WORKING ON THESE WHEN THE ENGINE IS RUNNING, IN CASE YOU CAUSE THE ENGINE TO SHUTDOWN.

Having read the makers instrucction manual and found the tools and spares kit, I closed the doors of the detectors & attached the "U" tube manometers to them in turn. In every case the vacuum was so great that all the water was sucked out of the manometer and into the measuring head!!.

I thoroughly cleaned the lenses and ports inside the detector heads, renewed the circular, sintered air filters under the covers, and checked the cover gaskets were in good condition.

Note:- The rough surface of these filters should be on the outside, air is drawn from the engine room, through these filters and across the lenses of the light beam, to prevent them becoming obscured by oil. The filters are a "throw away item that can not be cleaned effectively. If no spares are available, as a temporary, emergency measure, they can be cleaned using Electrical solvent cleaner, but this is not very effective.
Always check the cover gasket, I have seen cases where a "home made" cover gasket has completely blocked these air intake filters, there should be a cut away in the gasket allowing the air to pass between the cover and the casing from the bottom of the casing.

Next I closed the variable flow orifice fully and refitted the "U" tube manometer (freshly filled with water), and slowly opened the orifice until I had the correct vacuum reading, according to the instruction manual. This orifice acts a safety device, preventing a big increase in the vacuum if the reducing valve diaphragm fails.
Then I adjusted the pressure reducing valve until I had the correct vacuum for that adjustment (slightly less than for the orifice) in accordance with the maker's manual.

All the Detectors appeared to be functioning perfectly in Port, however, when the ship was at full speed at sea, one detector went into alarm with the top red LED, No. 14 illuminating. Checking with the instruction manual, this LED indicates incorrect vacuum in the Detector.

This can happen because when the engines are all stopped, the engine room supply fans create an overpressure, above atmospheric pressure in the engine room, as the load on the engines increase, they consume more air from the engine room, and this overpressure reduces. The Crankcases are directly connected to atmosphere outside the engine room through the crankcase breathers or vent pipes so the pressure inside the engine stays constant at all times.
Because of this, after initial adjustment with the engines stopped, it is sometimes neccessary to make a very fine adjustment of the vacuum with the engines at full power.

Once the Oil Mist Detectors were all adjusted correctly and proved to be working correctly, all the variable orifices and reducing valves were locked in position with locking wire, to prevent any accidental adjustment.

If a continuous sequence of red LEDs are lit, from the bottom of the collum upwards, that is an indication of the level of oil mist, more light = higher mist level. If an individual LED lights up, refer to the makers manual as it is warning of a specific fault in the oil mist detector rather than the oil mist level.

Sometimes it is possible to get a spurious alarm and even shut down of the engine caused by water in the Lubricating Oil. This can usually be spotted by looking inside the oil mist detector, if there is a deposit of emulsified oil inside, the alarm was caused by water vapour. Then you have to check the crankcase, oil coolers and purifiers for water leaks.
Another cause of false alarms can be piston blow past.
I hope this helps someone out there.

BP
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JK
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Re: Tips & Tricks

Postby JK » Tue Jun 22, 2010 3:03 am


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Pacific Barbarian
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Re: Tips & Tricks

Postby Pacific Barbarian » Tue Aug 03, 2010 9:35 am

The post on the Oil Mist Detector was very informative indeed. What I learned from it that I never knew was that the synthered bronze filters must be with the rough side on the outside!

OMD planned maintenance is very important. The funny thing is that most of the checks and maintenance only takes a few minutes with a trained hand, even if you really take your time.

Like you mentioned, it is indeed very shocking to discover the lack of knowledge of some engineering staff. What I normally do is I take my 2/E and 3/E for a demonstrative training session if they don't know. I was quite stumped twice on my last two vessels, when each time the 2/E, both have been 2/E for many years, did not know how to do the basic planned maintenance checks! Made me wonder how they manage to get by their past vessels, as these checks come up every 500hrs???

Fact is OMD's WILL shut down your engine. This not funny when you are working on for instance a Platform Supply Vessel, you are on DP next to a plaform with a fuel or bulk hose connected, with some wind and current not your favour! :shock:

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Re: Tips & Tricks

Postby astat101 » Thu Jun 25, 2015 1:34 am

JK,
Hi, I work for a company called Vestas aircoil who manufacture and design large diesel engine charge air coolers and I am interested in the condensation subject mentioned in your post. I thought that I would mention a few fairly known issues linked with condensation, this is when the air passing through and out of the turbo has sulphur content. When cooled, the condensation turns into sulphuric acid and corrodes the tubes causing obvious issues such as leakage.

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D Winsor
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Re: Tips & Tricks

Postby D Winsor » Thu Jun 25, 2015 3:57 am

Since this old thread had been activated and there was some discussion on Oil Mist Detectors.
I recently was able to use the OMD on a 4 stroke medium speed engine to find what turned out to be a cracked piston crown
When the engine was running at full power the percentage of oil mist concentration was consistently rising at every sensor.
The OMD was inspected for possible issues and was found to be full of oil residues.
The unit was cleaned and the readings remained high
A crankcase inspection and compression test was done on the engine but revealed nothing out of the ordinary other than the crankcase pressure seemed to be higher than usual and and the crankcase pressure had increased in the past due to broken compression rings
The engine had recently been overhauled with 5 of the 6 units being rebuilt so it was decided to reduce the load on the unit that wasn't overhauled to see if made any changes. If there was a unit with a broken compression ring it was the most likely candidate. No change in the crankcase pressure was observed
It was then decided to check the other units and as soon as the fuel was cut on the next unit the pressure began to reduce and it was also noticed that the reading on the OMD also went down to a more normal level.
The unit was pulled the next port and the cracked crown was found
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

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Merlyn
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Re: Tips & Tricks

Postby Merlyn » Thu Jun 25, 2015 7:46 am

Reading old posts on this subject and B.P.'s mention of grinding the drill offset reminded me of when you are drilling and the drill wanders off centre the method used to bring it back to where you originally centre punched it. Out with your old tempered half round chisel, ( you know the one you used to cut oilways with in white metalled bearings ) and cut into the job a small Chanel the direction of which you want the drill to take to revert back to the centre. Carefully drill slowly and hey presto, the drill will wander back to the centre. That said you have to hope you don't hit a "hard spot" that sometimes exists in metal, especially if the job is a manifold or similar that goes from cherry red to cold throught it's life and can develop a diamond hard bit right where you want to drill.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Re: Tips & Tricks

Postby Vegman » Sat Jun 27, 2015 1:38 am

A few more tips and tricks...
When trying to remove old valve seats from med, speed engines, if they are stuck and you cant get them out with the regular tools try running a small bead of weld on them and then throwing water on , the expansion and contraction can "crack " the bonding between the surfaces. This sometimes works with other seized elements like pins ,liners and even bolts.
When trying to screw in very small electrical terminal screws in the horizontal position, rub the screwdriver tip vigorously for a minute or so on a metal surface, this will give just enough temporary magnetism to hold the screw on the tip of the screwdriver for long enough to get it in.

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Merlyn
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Re: Tips & Tricks

Postby Merlyn » Sat Jun 27, 2015 7:22 am

Something That I can't remember the last time I did it, again done more in the past than now. Hydraulic extraction of bushes in blind holes? Spigot bushes were a favourite, flush down inside the flywheel so even if you had a three legged internal extractor because there was no clearance down the bottom of the bush for your super slim legs to " hook " into you found a good fit mandrel, ( or turned one up ) a drop of EP 90 or 140 if you have it poured into the hole, lump hammer out and give it several. Worked for that back camshaft bush in a blind hole in the crankcase too in some cases provided it wasn't one of those thinwall steel bushes sprayed with whitemetal. Work a no 2 tap into him with a bar welded onto the tap, weight with a hole drilled in it, weld / screw a cap on the end and slide hammer him out. I suppose the use age many many years ago of the introduction of needle roller bearings especially for the spigot bushes reduced the hydraulic extraction method as all the effort of the compressed oil runs around the needles and subsequently is lost.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Big Pete
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Re: Tips & Tricks

Postby Big Pete » Sun Jun 28, 2015 6:13 am

I remember "Slide Hammers" as favourite makers tools on a lot of German equipment, for knocking things, out rather than in.

I have removed a lot of valve seats from cylinder heads by turning down old valve spindles, putting them in the head and welding the outside edge of the cut down mushroom to the seat and then hammering them out. If you "overcook" the welding, it contracts on cooling and the seat falls out.

BP
It is always better to ask a stupid question than to do a stupid thing.


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