Tagged With "Chemical"

Topic

Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

chary tatta ·
Dear AMP team, This case is about 2 diesel generators (DG) Engine free end Axial vibration found high. Attached is the DG vibrations recorded on Alternator end- Satisfactory, Engine end Axial vibration High. Attached the vibration velocity FFT spectrum, further any other files required like time wave form, Acceleration FFT and time wave forms shall be posted. Engine rpm is 900. Generator appearance in images for your kind understanding. Appreciate your participation on this case study.
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

Walt Strong ·
Both engines appear to have the same high vibration with the frequency of 21,000 CPM and harmonic at 42,000 CPM. These frequencies are not integer multiples of engine shaft speed (24.4 X shaft speed). I suspect the frequencies are generated by the accessory gear drive and possibly the lube oil pump. You would need the details about the accessory drive to try to track down the source and ascertain whether there is an issue or not. Walt
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

John from PA ·
Review the thread at https://www.maintenance.org/top...ation-on-a-generator especially is this is a 12 cylinder 4-stroke diesel. I say 12 cylinder, 4-stroke because your spectrums are "rich" in 1/2 order components, indicating likely 4-stroke diesel and if the diesel was at 875 RPM, then 21000 cpm could be generated. But in any event the thread I point you too had a similar issue and it required replacement of the rubber elements in the couping.
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

chary tatta ·
Greetings Mr. Walt Strong and Mr. John, Thank you for your professional assessment and the replies given from your side most welcome. As per Mr. Walt, Yes, the Diesel generator gear train running with One Lube oil and One Cooling water pump. The acoustic levels are also can be heard from the gear train. The axial high vibration related to Thrust bearing condition too for Axial movement. Appreciate your comment. As this engine is running 4 stroke 6 cylinder Yanmar make 2012 model just 5 years...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

chary tatta ·
Greetings Mr. John This is Yanmar marine diesel generator and firing order is 1-3-5- 6 -4-2(Anti-clockwise). I assume that you might have seen Alternator end bearing vibration readings which are in satisfactory zone. Engine free end H V A readings and Axial reading only showing high value with 21.3K and 23.4 K cpm. Thanks and regards Chary TSR
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

John from PA ·
Any chance you know the firing order of the engine? Even though not a 12-cylinder, I'm not yet convinced that the 21000 cpm isn't engine related.
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

John from PA ·
Hmmm, I may have messed up. A 6-cylinder, 4-stroke engine at 900 RPM has a firing rate of 2700 cpm. That would be the 3rd order of running speed, not the 4th. The 21600 cpm, what you are calling 21300 cpm is 8X of the firing order or 24X of running speed. As you likely are aware, a diesel has certain criticals that are classified as "very dangerous", "dangerous" and "probably of little concern" (SNAME designations). For example, a 6-cylinder, 4-stroke engine with a firing order of...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

John from PA ·
Good point that the alternator axial looks OK but the alternator design might explain that. For instance does the alternator even have a thrust bearing or could the rotor just be floating back and forth in its axial clearance? I'd also review what was done relative to the new coupling (was it really a "new coupling" or just the elements?) and making sure the new couplings were installed properly. Sometimes, depending on coupling make, it is recommended that the elastomeric elements be...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

chary tatta ·
Greetings Mr. John Thanks for your interest and reading through the machine to find out the 21 k components analysis. 1. The coupling was opened up in docking but the superintendent was unclear that coupling elastomeric elements renewed for both DG1 and DG 3. 2. The DG are 5 years old as the vessel delivered 2012 from a China shipyard. 3. No much information on dockyard alignment procedure, at a later date when all work done reports submitted by the ship yard to office I will explore it for...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

Walt Strong ·
A lot of speculation without confirmation of accurate frequencies and shaft speed.
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

John from PA ·
Bill, my choice of descriptive wordings are not my own but are extracted from Marine Engineering, published by the Society of Naval Architects and Marine Engineers.
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

William_C._Foiles ·
When it was mentioned, "very dangerous," the word dangerous may be over done. What is typically seen at some frequencies is that the forces add together on the crank shaft considered as a rigid body, which is a good approximation for the lower frequencies. Look up star diagrams in relation to recips (diesels in particular), and you can find these major criticals yourself. By memory at my first look at the orders for these " very dangerous" criticals the orders don't follow the pattern that I...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

chary tatta ·
Greetings Mr. John, Mr. Walt Strong, Mr.william , Thanks for your contributions in the captioned subject. 1. The vibration levels are not very dangerous or even at dangerous levels. 2. The radial vibrations are in satisfactory range, for marine DG sets, IACS allowed 18.0 mm/s limit is satisfactory. 3.The Generators rpm is 900 and there will be variations by + or - 10 revs when load and down by way of starting stopping various machineries. 4. The peak frequencies and amplitudes are very clear...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

William_C._Foiles ·
Not only for legal reasons, people are advised not to use such descriptions as dangerous. Unless qualified, it is not precise. A vendor sells me a machine with a dangerous critical speed and it fails, people are injured or killed, there is a fire, etc. Whether caused by the dangerous machine or not, at a minimum there is going to be paperwork. More likely is time in court, fines, or other legal penalties. Besides, such terms add no technical value. I had to deal with a number of reports when...
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Re: Diesel Generators Engine side Axial vibration High on a 17000 DWT Chemical Tanker vessel

John from PA ·
Marine Engineering is a 2-volume reference book on subject related to marine engineering/naval architecture. It is edited by H. L. Seward, probably now deceased, but at the time of my edition he was Professor of Mechanical and Marine Engineering at Yale University. The books are old, out of print, but happen to have a very nice section on dynamic effects that was written by Frank Lewis, Professor of Naval Architecture at MIT.
Topic

45000 dwt Chemical tanker Diesel Generator 4 high vibration on Alternator bearing

chary tatta ·
Greetings team, on 8th July I attended another Chemical tanker and DG no4 alternator bearing Horizontal overall vibration showing 23.4 mm/s in velocity scale. The Marine classification society satisfactory limit is 18 mm/s. Attached the engine and Alternator end vibration spectrum FFT in velocity. All engine details are available in photo sheet. Appreciate your feedback. Kind regards Chary TSR
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Re: 45000 dwt Chemical tanker Diesel Generator 4 high vibration on Alternator bearing

chary tatta ·
Greetings Mr. John, Thanks for your follow up. Please find attached at 5000 cpm HVA plot. Regards Chary
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Re: 45000 dwt Chemical tanker Diesel Generator 4 high vibration on Alternator bearing

John from PA ·
One thing that might be helpful would be to make the frequency scale 5000 cpm. Your engine plots for instance go to 60000 cpm and virtually everything of interest is crammed into the lower 10% of the plot.
Topic

Gearboxes and pumping units

RobPme ·
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