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Asset Condition ManagementPosts About vibration/alignment/balance
fluidizing blower high horizontal vibration(what else can be done, running out of ideas?)
Registered Member for example, one of our three vacuum blowers. please note the silent-blocks between blower and foor [ more ]
Registered Member I don't like this system of anti-vibration because it works in one verse only, from top to bottom. from bottom to top the bolt is a rigid connection. I prefere a silent-blocks like in picture [ more ]
Registered Member Re: fluidizing blower high horizontal vibration(what else can be done, running out of ideas?) [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Overhung Mill With High vertical Vibration
Registered Member If welding is ok, have checked for soft foot possiblity. Soft foot can also cause high vertical vibration. [ more ]
Registered Member I have looked over every inch of this mill. Cant spot any broken welds or loose bolts. Im thinking excessive clearance on the shaft/Bearings. Can that cause directional vibration like that? id think the horizontal and vertical should be close to the same displacement. [ more ]
Registered Member Have you checked any welding that may be involved with the mounting? I’m thinking perhaps a crack in a weld that might not make itself apparent visually. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
GRADUAL CHANGE IN GAP VOLTAGE TREND
Registered Member Dear FSX, Apologies. When digging out this issue, I am getting many new information. I am just two month old in this plant. There are no SDs after 2018. Even in 2018 SD, they just opened the compressor top cover, inspected and closed it seems as they had some issues related to seal removal / its spares. I thought that the ESD will change the shaft property similar to electrical run out and the shaft position is not really changing. I could not understand why this extreme shaft position... [ more ]
Registered Member Hi Shan For the Steam Leak, there are many things in Gland Seal System common to both ends e.g. some manufacturers provide Gland Steam Condenser which serves to collect steam leak form both ends and maintains slight -ve Pressure at outer End of Seals to ensure there is no Steam Leak towards Bearings. Higher Pressure in Gland Steam Leak off to condenser can cause leak at both ends. so you need to physically rule out this and verify Gland Seal system parameters (mainly Pressure) are within... [ more ]
Registered Member " It is possible to have a steam seal leak that directs steam toward the vicinity of the proximity probe. This in fact is what I've generally seen through personal observation. This tends to lengthen the probe due to thermal expansion, hence making the probe gap voltage move positive, e. g. from -10 to -9 to -8... " There is no obvious leak near ST area. And moreover, this phenomena has occurred at both ST DE and NDE from exactly same time (March 2018). I am bit doubtful. " Let me ask this,... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Hump in an FFT spectrum.....!!!!
Registered Member These are clearly harmonics. Harmonics tend to make these humping patterns and it can be difficult to reproduce these in simulation, but thanks to some very good fortune I happened to simulate a distortion at 45° on a sine wave some time ago and got a very similar pattern. Notice that I mentioned the angle which is the crucial variable, that's Bullard Laws of Harmonics #2. The pattern of humps and notches is due to the phase angle where the distortion intercepted the sinewave. Everything... [ more ]
Registered Member Mathematically - oh that devil - one can show that pk >= rms. Take away some rms and the pk can go up. Example. Take a square wave. Low pass filter it (ideally) removing all but the first harmonic. The first harmonic has a greater pk or pk-pk than the square wave, but obviously it has a lower rms value because of the removal of the harmonics. I think that this has been discussed on this forum previously; someone may be able to find a link. [ more ]
Registered Member My point of view is that hump in FFT is multiple forcing function. The example that you present is a sine wave position, superimposed sine wave represent the raw data of waveform at diffrent direction and this will be will filtered to form sine wave for a better analysis,the hump in FFT with increase noise floor cause irratic or undirectional time waveform. Every forcing function have thier own time waveform to analyzed if it is a pure sine wave, irratic, undirectional etc. correct me if im ... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Non-synchronyezed peaks at Main lube oil pump with BPFO defects
Registered Member Thanks for comment i gonna check the pump type bearing to confirm first and then we will make bump test to identify the Natural frequency of moto-pump. regards Anis [ more ]
Registered Member Dear ANIS VA , you have made a great consolidated report, from the data i am suspecting a pump bearing innerrace defect since, 8.56 is modulated with 1X, there are some cases we can get such strange frequencies with out matching with bearing fault frequencies. my suggesting for you to inspect any one pump bearings thoroughly [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Cat1 certification
Registered Member Re: Cat1 certification [ more ]
Registered Member Training hours should be part of the requirements. I have not seen them count real education in the subject. [ more ]
Registered Member I suggest you open the Certification Handbook at https://www.vi-institute.org/w...20-Cert-Handbook.pdf and specifically go to the bottom of page 9. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
NSPECTR Manual
Registered Member Nspectr is still offered through Emerson's AMS Machinery Manager. But.. Will not be in the new AMS Machine Works software that is replacing MM. With that being said MM will still work like normal but there will no longer be improvements made to the software as the main focus is now Machine Works. It is nice having the artificial Art Crawford right at your side. -Chris [ more ]
Registered Member Don't know myself. I do know that the CSi brand is no more according to Emerson. You would need to approach them directly to see if they still support Nspectr. [ more ]
Registered Member Is the Nspectr program still offered and supported by Emerson-CSI? Walt [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Spikes in direct signal due to Possible Aliasing
Registered Member I no longer have the 3500 config software as I'm retired but as best I recall, the frequency ranges that are displayed (and user selectable) are a function of the transducer selected. In other words, should you select an accelerometer then you will be able to select a range that includes out to 10 kHz, or perhaps even more. Also, the best way to check for spiking due to electrostatic discharge is to view (with the 408) multiple direct orbits, and by multiple I mean 50 or more over a several... [ more ]
Registered Member Dear John, William & Walt Many thanks for useful inputs The Grounding Brush on Steam Turbine was connected to ground through an Ammeter. Ammeter resistance was found high and Grounding Brush was directly connected to ground and the Full Scale Spikes we were seeing in ADRE 408 DSPi vanished. However after some time we started seeing persistent increase of about 40 microns in Direct Value on all probes on ADRE 408 DSPi. However again there is no change in direct Vibration Value on DCS... [ more ]
Registered Member We both have a few "good" years at BN under our belt; even worked in the same office for awhile. I'll let readers determine the "good" years! [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Setting Parameters to Detect Misalignment
Registered Member Good morning, Flexible couplings can accept some misalignment before transmitting that force to the machine. As vibration analysis is the detection and measurement of force, then if the misalignment is not enough to impart a force to be detected then it cannot be seen in the vibration data. Thermal changes also play a role. If alignment is not measured while the machine is at normal operating temperature and compared to it's non-operating alignment then discrepancies can occur. Precision... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
High 1x Axial at Motor
Registered Member was the case been solved? [ more ]
Registered Member Hi, in my experience when we have axial vibration on a fan like this or similar (belt drive for example), we check first the basement, to find if is well connected and the dumpers if have the same height, to avoid axial oscillation (like some table at restaurant) or you have to stiffen the baseplate (sometimes welding a X beam). [ more ]
Registered Member ❤️
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Asset Condition ManagementPosts About vibration/alignment/balance
Effect of using an extension bar to collect vibration
Registered Member I have basically always used an extension pole since the beginning of my condition monitoring career. Best I recall, it started back in 1987. Seems like just yesterday. Like the ole saying, "time flies when doing something you enjoy". The pole I used was 4 1/2 feet at its shortest length and extending out to near 10 feet. Had a swivel ball connection at the transducer mounting end and a 90 pound "pull", dual rail magnet on the transducer. Never ever had many, if any, signal problems from... [ more ]
Registered Member If you are reaching out to place an accelerometer with magnet base, the surface conditions may not be optimally clean or smooth and flat. Any rocking movement of the accelerometer, possibly aided by the pole vibrations can produce unwanted low frequency vibrations and inhibit high frequency vibration response. For some measurement situations I designed a pole bracket that would allow the accelerometer to be attached and then disconnect from the accelerometer for the measurement. The pole... [ more ]
Registered Member You are correct in your assumption but you can't really quantify the effect. Keep in mind that much of what we do is to establish a trend so we can (hopefully) be attuned to a change. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
SCR Frequency
Registered Member I have 2 550kw DC motors, but the vibration is high when using 1 of these 2 motors. The spectrum show 300Hz at hight vibration motor (SCR frequency). Someone be able to tell me what troubles with hight vibration DC motor? Thanks! [ more ]
Registered Member As pointed out by others, it depends on whether the specific drive is six-step, etc. The real difficulty is that a LOT of drives out there particularly of fairly old vintage, get remarkably noisy, with respect to line frequeuncy generated vibration, at low loads, which can lead to confusion as to whether an SCR misfiring, etc. Another thing that particularly older vintage DC drives are senstive to is phase imbalance (voltage) on the input side....this can produce all manner of odd vibration... [ more ]
Registered Member Hi Jamie, Is this drive half wave rectified (3 SCR’s) or full wave rectified (6 SCR’s) You will always see electrical activity in the spectrum but I find it’s best to trend the values taking into account the loading e.c.t and don’t jump to conclusions, here is some info for you; DC Drive Problem Symptoms: DC Drive Problems typically show up on a vibration spectrum as amplitude peaks at multiples of FLine between FLine and FSCR. With a full-wave rectifier, this includes 2 x FLine, 3 x FLine,... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Misleading inputs
Registered Member First of all the maker of the machine is the best source of information regarding alarm and danger set points. I also do not see any signs of ESD in the data you've presented. You might want to examine the document at https://dam.bakerhughesds.com/...-App-Note_R4-pdf.pdf and specifically page 13 (as numbered in the document). In the content you will find Mount the probes at the thrust bearing end of the machine and within 12 inches (300 mm) of the thrust bearing to minimize the effects of... [ more ]
Registered Member Any feedback regarding the above? The axial position alarm set points were adjusted with a very tight range. The cold axial float is 0.25mm, alarm set point is 0.25 and the danger is 0.38mm. I feel like it need to be adjusted to alarm 0.38mm and danger 0.50mm. AM I RIGHT? [ more ]
Registered Member Mr. John, I tried to gather more data as i can to determine the spiking in the orbit plot and the shaft centerline behavior. please see the PDF file attached. Regarding the probe mounting I couldn't get a solid answer to it. For this time I was able to get the steam parameters across the stages and all of them concluded that the rotor should move away from the probe. Inlet pressure: 41.1 Bar After 1 stage pressure: 22 Bar Extraction pressure: 10.5 Bar After extraction pressure: 5 Bar Exhaust... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
ID FAN VIBRATION
Registered Member Checked DBSC of coupling for axial vibration and fire horizontal vibration need to check any crack in impeller shroud area..or any foundation looseness.. [ more ]
Registered Member Were you able to determine the sideband frequencies around so many of the "harmonics", including the 14x bladepass frequency? Thanks [ more ]
Registered Member First suction is for motor non drive side the second is for motor drive side the third is for fan drive side and fourth for fan non drive side [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Vibration limits for exhaust fan
Registered Member Thank you @Registered Member @Registered Member fan is operated by vfd motor through belt drive; nominal speed 800 RPM. [ more ]
Registered Member May we know the speed of the fan? [ more ]
Registered Member You might want to review the presentation at http://acc-usersgroup.org/wp-c...ibration-in-ACCs.pdf , especially the slides from #10 onward. Otherwise, perhaps think of purchasing the applicable ISO specification. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
SSS Clutch High Vibe Shutdown at 20 MW
Registered Member Thanks for the update. We all learn considerably more when the resolution is shared. [ more ]
Registered Member I just wanted to say thanks for all the help! We found the problem to be that the feet had not been fully torqued by several hundred pounds! Runs smooth as butter now. I hope if anyone reports a issue like mine again this response will come in handy. [ more ]
Registered Member One of my engineers is talking to GE, nothing yet. What SSS wants is to have GE and Brush and themselves onsite to troubleshoot the issue, big dollars. I agree, SSS clutches are incredibly reliable, worked with them many moons ago. The proper channels are taking longer than i would like. I would like any info as to how a SSS clutch could act this way. Or any one who has perhaps had this event occur. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Configuring collection specs and filters in EMonitor for low speed machines
Registered Member For the compressor, it runs at ~327 RPM, 6 throw, 2 stages. As for the transducer, it's an IMI. So far as I can tell, the cable is in acceptable condition; when used on other machines I get readings that A.) make sense and B.) are within 5-10% of readings collected using our second data collector. [ more ]
Registered Member Key question, already asked by Robert U, is "What speeds are you looking at on the compressors?" I see that the transducer has a frequency response from 180 to 540000 cpm so it's conceivable it would work. It does require a constant current power source (see attached, from the manual) so the obvious question is that being supplied? Is the cabling good? so an obvious ques [ more ]
Registered Member What is the manufacture of the Velometer? I looked up the an IMI EXVO622B01 and it comes back as a high frequency velocity sensor. What speeds are you looking at on the compressors? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Skislope
Registered Member Gilsi's Quote: "I don´t use same sensor for online or portable but they are similar, both Hansford but Portable is top connected and Online side connected.". I understand this. What I was saying is, can you disconnect the online transducer's cable, which is showing the data as "BAD", and then connect your portable transducer's cable to the online system's transducer and then collect portable data to see if you are getting the same bad signal with the portable analyzer, which is now connect... [ more ]
Registered Member Hi, Try increasing the settling time before data collection. Just my opinion. [ more ]
Registered Member Thanks guys, very valuable ! Lot´s of situations that can affect the sensor I don´t use same sensor for online or portable but they are similar, both Hansford but Portable is top connected and Online side connected. See settings for sensor. All 48 sensors have basically same settings....only two have wrong bias and several have good bias but still skislope See screenshots from both online and portable software. And I added Hansford specs for this sensor I was playing with filter yesterday... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
High 2x axial vibration motor for end suction pump
Registered Member Check coupling condition and shaft alignment. [ more ]
Registered Member Yafie, 2 cents on your post....the images you have posted are great, can you post images of all sides of pump base. I see softness in how the current base is suspended above a hollow pocket, does not appear to be level and no axial support for motor. The solo run of the motor has very high 2x axial, as Ralph stated above, you must make sure it is 2x or 2x line frequency to begin with. As Ralph also stated, loosen one motor foot then retighten, if the vibration dropped this foot is in a bind. [ more ]
Registered Member In response to you statement on 2X LF, have you confirmed that the "2x" is not 2X Line Frequency (100 Hz), using High Resolution and/or "power shut off" while "live" monitoring of the "2X". Could be a softfoot problem if the 2X disappears instantly on shutdown. Thanks, Ralph [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Cement Industry Raw Mill Vibration Monitoring
Registered Member 1. You can mount vibration sensor no rocker arm bearing housing in all direction. Also installed roller proximity switch to monitor running condition material bed height and also providing tripping when bed height reduce at some level. 2. Spectator vibration is higher if body vibration is higher than provided body stiffener for strength the mill body and reduced vibration. [ more ]
Registered Member "Our Raw Mill creates too much vibration and mostly it is coming from the grinding rollers running inside when they come in contact with the rotating table." "I found a very fine powder of material on the bed. The fineness of material troubled me at that time as I believe for a stable operation we need the right thickness of a material layer on the bed neither too fine, nor too thick." Regarding Question 1: My experience was with vibration measurements and analysis on Raymond vertical coal... [ more ]
Registered Member Here are the Oil analysis reports. Could you (experts) please provide valuable feedback on this? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
possible Misalignment ? Vibration issues with An auger electric Motor
Registered Member Mostly acceptable limit up to 0.07 [ more ]
Registered Member So I've conducted a auger shaft runout today, can you let me know if this shows an eccentric shaft from the reading or if it's normal ? It's the first time I've done one of these so not sure what the reading actually signifies, so any advice would be great! Many thanks [ more ]
Registered Member Thanks walt, Yes at least that gives us a clear reason why the drive end was warmer than normal. oh okay that makes sense, it is running off a VSD so it starts up slowly and works it way up to 1440rpm. i will look at the shaft with a DTI gauge. should be able to give this to the manufacturer to show this issues surrounding this asset [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
my first exposure to a gearbox with high vibration
Registered Member If abnormal sound present in input side than check pinon teeth pitting may be present. What is issue found date 01.05.21 Vib. Reading is Ok ☺️☺️ [ more ]
Registered Member I’d be digging up the bearing numbers as well and establishing the bearing related frequencies. [ more ]
Registered Member @Jim Carrel @John from PA I will come back with more details. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Misalignment of Shafts Rotating at Low Speed
Registered Member IMO, this case is pointless, no matter which accelerometer you use. Very unreliable method. [ more ]
Registered Member Have you thought about using a servo accelerometer. It is good to d.c. I had an opportunity to visit the hydroturbines at the Hoover dam, and the engineer there had installed servo accelerometers. Unfortunately, for me and the generator, there was a ground fault just before I was able to travel. The generator was toast. The guy at site did get some data from the accelerometers of the failure, as I recall. [ more ]
Registered Member Also remember to set from your analysis parameter set linked to the asset the lower freq. to capture to be 0.0 CPM or Hz , If your software allows you to make those configurations. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Motor shaft broken
Registered Member I would not reduce the number of belts without some further analysis including perhaps establishing the load on the motor (Becar has suggested that earlier). As I've already stated: "There is a belt tension calculator at https://www.mitsuboshi.com/eng...alc_tool/v-belt.html that does a good job in calculating belt tension and static shaft load. One variable you need is pulley center distance. I had calculated, based on the belt length and pulley sizes you provided, a center distance of 2180... [ more ]
Registered Member The broken shaft shows as per failure analysis it is heavily loaded and due to bending stress shaft failure had occurred. No progression marks means the fatigue load was constant. The instantaneous zone is relatively large, indicating the shaft was heavily loaded. Any belt driven machine, if there is an misalignment only the belt should fail if shaft fails that means belt tension is high.so instead of 10 belt try to run with 5 belt after proper sheave alignment. check the vibration and... [ more ]
Registered Member JohnPA may be on to something here. In 1 week there would be approximately 10 million cycles on the motor shaft. One should be able to estimate the loading. With the material properties One could look at whether there could be a fatigue problem. This point has a combined loading, too. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Boiler Feed Pump Issue
Registered Member you said that OB is inactive, IB is active side and the problem here is the force is now more on OB side, isn't it. If so, reducing piston will make more force on OB side, not IB. In our plant, most of pump have active side at OB side. Sorry to ask but are you sure that the DBSE is correct? How do you check it? [ more ]
Registered Member The pressure reducing bushing and sleeve were both replaced. I did notice that the 3rd party vendor used a different material for both. For the PRS, it's supposed to be 420 and they used 416. For the PRB, it's supposed to be 440 and they used 420. But as I reply to another user, the 3rd party vendor found that the impellers size (the "as-found) actually gave use a higher predicted H-Q curve as opposed to OEM's. The plant had mentioned previously that the pumps were at some point "upgraded"... [ more ]
Registered Member For pump 2B, we used the OEM, for the other two pumps, we used another vendor. The latest that we have heard from the 3rd party vendor was that the "as-found" impeller size would actually give us a higher H-Q curve (There's been talk at the plant that these pumps were "upgraded" at one point or another but no documentation has been found). That being said, the 3rd party vendor has proposed increasing the size of the pressure reducing bushing and decreasing the size of the pressure reducing... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Vertical Motor NDE high vibrations
Registered Member Hello, If you still facing this issue, As you said you performed the on site balancing, at that time what was the level of the sump? what is the fluid inside the sump? Thank you [ more ]
Registered Member I agree with Mr. Ali M. Al-Shurafa’s recommendation, do a bump test of the machine can help support findings and suspected causes. A minimum separation margin of 10 percent shall exist between the natural frequency(ies). VastOcean [ more ]
Registered Member This is a new machine. Motor is fine.. It's a case of mounting resonance issue so we are planning to take FEA route for a permanent solution Nagaraja [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Asymmetrical stiffness shaft
Registered Member Hi William, thanks for feedback Once rubbing occurs tip shoe will grind blade tip thus leaving a specific pattern on blades and this can happen in test runs, afterwards, if clearance was maintained within specifications of Manufacturer, then is there (normally) a chance for blades rubbing to continue to occur during every run? [ more ]
Registered Member My impression of what has been said in the last posts. Rubbing does not make the rotor asymmetric. Asymmetric rotors do not split criticals (in the stationary frame of reference as we use). I am not sure your understanding or instability as in rubs create instability (perhaps, perhaps not). Blade wiggle makes it impossible to balance GP rotors. I would challenge this; there are scores of engines operating well in service around the world. Stationary blades (where wiggle does not create... [ more ]
Registered Member Hi everyone I am back with new observations according to discussion from Walt and William _C_Foiles. GG /GP blades rub is very common, and is observed. What are possible reasons that increase the rub is definitely amount of unbalance along with other parameters. There is often wiggle in blades when fixed in GP disks, this wiggle makes it impossible to balance GP Rotor well within a certain amount /allowance, thus rotor rub will be proportional to it. Rub creates Unstability of rotor and... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Vibration limitations of high pressure triplex Plunger piston pump
Registered Member Hi did you manage to find the limits? [ more ]
Registered Member Dear John , thanks for your valuable time, in iso 10816-6 which describe the recip pump vibration limitation but there is not describe the class specifation my question is how can we find the vibration class for that (Pump driven 6.6 kv motor 1489 rpm ,pump have 3OO bar pressure) [ more ]
Registered Member I believe API 674 and ISO are the design specs for plunger type pumps. Unfortunately I don’t have either so I don’t know to what extent vibration may be discussed. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
why shaft worn pre alarm doesnt appear
Registered Member this is bearing with clearance between shaft. note noise floor indicating clearance this is peakvue spectrum: I think that when you read a unbalance very small, and many other peaks like clearance or 1/2 armonics, the support is very damage and the bearing turn around the shaft o the support. it's just my opinion [ more ]
Registered Member Why the CSI alarm did not activate while the shaft of the fan has a severe wear? There are many possible reasons. Here are a few to consider: 1- The configured alart set point is too high. 2- The data collection configuration is not correct for this machine. 3- The measurement is not taken while the vibration is high (e.g. the readings are unstable) 4- The field data collection is not correct (e.g. the location of the sensor is insensitive to the fault). Regards- Ali M. Al-Shurafa [ more ]
Registered Member theres is a non integer peak a little over 3x whats that? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Using four channels measurements on route based surveys with Microlog AX
Registered Member Yes it can collect 4 channel, but there isn't an issue with is uploading the measurements to Observer, I think it only works with ARM software. [ more ]
Registered Member https://www.skf.com/us/product...able-systems/cmxa-ax The above link states the unit is capable of collecting 3 or 4 channels simultaneously https://skftechnicalsupport.ze...0-User-Manual-rev-E- Link to manual Hope this helps, Dave [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Motor Abnormal Sound
Registered Member I think about something like this: this bearing is fixed to the support, so I have some clearance between bearing and shalft... it's only my opinion [ more ]
Registered Member dear all, for me if you see many armonics like yours, probably you have a clearance betwen bearing and support. also, the floor noise indication a clearance betwen bearing and shaft... if you can see the old grease of bearing come out rust color, for me you have a clearance it's only may opinion [ more ]
Registered Member Did anyone notice a pitch change when the motor was greased? Your demodulation spectrums shows a early bearing defect.....what does your velocity data and timewaveform data look like? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Geothermal Turbine close to Volcano
Registered Member If you are worried about the change, the report should contain measurements before - after. 2x rpm spikes are common on generators and are caused with some eccentricity that causes changing gap between rotor and stator. [ more ]
Registered Member I agree with you but they can see from their monitoring equipment that vibration is quite higher than before. I see axial vibration in generator has two dominant spikes ? Could that be the reason Anyway I was asked if I could find out why now this extra vibration occur. Any input would be appreciated [ more ]
Registered Member I can't see any high vibration levels to be worried about. I've seen agregats with twice as much RMS vib. velocity working for decades. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Motor running in offset from magnetic center
Registered Member Same problem observed in on Process Fan Motor in de coupled condition motor run with megnatic center after stop the motor motor rotar shifted. Motor Bearing is white metal and coupling is Pin bush. [ more ]
Registered Member @ELECTRICPETE ... coupling is Flender rupex RWN Thank you EDINSONINDIA @DAN.. Thank you DAN.. This sounds convincing we will inspect the coupling and check for any rubbing marks.. [ more ]
Registered Member I think as ELECTRICPETE points out, its probably not a problem. Dans explanation makes perfect sense to me as well. "A lot is possible. But most of the time a little is sufficient." [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Is there something wrong with my computer or what?
Registered Member John, for some it makes a difference whether you speak of the month of Ramadan or a name of God (I have heard different views about this name.). Some might take offense - NOT ME. It was mentioned in a meeting today that it could be overcast (or a dust storm) at the end of the month of Ramadan. In some countries it takes a reliable source to see the moon to declare the month is over or has started. I am not sure how one can see the moon before astronomy says one should be able to but, I have... [ more ]
Registered Member Thanks John. I changed mine. [ more ]
Registered Member I suspect that few people use the feature, which at best is an obscure process to set up. One person I’ve seen use the feature is OLI and even he had to ask about how to set it up. See https://www.maintenance.org/topic/sinature [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Strange FFT
Registered Member The cage's duty is really to basically keep the balls/rollers in "position" as they (the balls/rollers) travel around the inner and outer races. The cage usually responses at its fundamental frequency when some other defect is present and "excites" the ftf. A bad ball or roller does this quite easily. IMO. I have seen but one (1) case where the ftf was showing in the data with no other visible bearing defect frequencies showing. When the bearing was removed, there were no race or roller... [ more ]
Registered Member Yes...you are right. These spikes have 15,4 hz between them. Why appear Cage (1x) so small [ more ]
Registered Member Ouch....sorry Ralph. Been overloaded. Yes, the bearings have been removed. They are in bad condition. I have asked owners to put them aside so I can clean them and hopefully see the defects. I tried to do what you suggested but the spaces between spikes. Actually I am having troubles with software.... I am trying now. Please wait. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
how to check the sensitivity of rotor balancing system with a rotor
Registered Member I have used Excel for polar plots of balancing, dial indicator and ultrasound data. I found that using the Radar plot with at least 8 data values is visually suitable. John's reference link looks handy for this method. I have found two "tricks" on occasion that helped. 1) Rescale the data, as needed for visual appearance 2) Overlay a circle (I use Bluebeam Revu) to find circle center of data and variation from mean value. There are sources on Internet for Excel add-on for Polar Plots. [ more ]
Registered Member Some guidelines on developing a spreadsheet generate a circular plot can be found at https://peltiertech.com/polar-plot-excel/ [ more ]
Registered Member As per 612, 7th Edition, details are explained and the i have done this exercise many times with rotors. I am manually drawing the circle, Is any one using excel programmed/spread sheet for this to get the result accurate with circle. In other OEMS, like Toshiba, japan, after completion of High speed balancing, They will also do Sensitivity check by putting a known mass at known angle and check the response of the weight on the both planes.(only one run per plane). Based on this data I was... [ more ]
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