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Asset Condition ManagementPosts About vibration/alignment/balance
Formula for converting FPM to RPM
Registered Member It's almost like I was waiting for someone to ask that. [ more ]
Registered Member Oh no...what have I done! <g> Patrick, I like the bearing geometry calculator and some of the FFT calculations too. Some vendors may not appreciate me providing an easy way to calculate just how long that 100,000 line FFT at 100 Hz is going to take! No promises on when....but I'll keep the good ideas in mind. Jon Spintelligent Labs [ more ]
Registered Member How major of a revision? I like the new look. Do you want to tackle bearing frequencies? At least from the geometric side (x diameter, y number of rolling elements, etc.)? Or CSI's bearing info is easily eported to a text file. How about resolution, LOR, Fmax, time to collect z number of revs. Or converting the AFBMA bearing numbers to SKF numbers? You know, in your spare time. [ more ]
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Asset Condition ManagementPosts About Motor Testing
What causes a motor to draw higher than normal amps
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Registered Member I agree with Ron, the amps should have decreased if you trimmed and impeller. Pumps operating in parallel MUST have the same sized impellers, the pump with the smallest impeller can not overcome the discharge pressure of the other pumps and thus cavitates. A pump can draw the same amps if the impeller is trimmed....due to the impeller was too big to begin with and trimming it brings it back onto the pump curve? Had a customer once with a 2300HP 300 rpm pump have flow issues due to sediment... [ more ]
Registered Member MikeC, It looks like the best evidence you could provide might be a diagram of the piping arrangement. Can't agree more with EPete. Turning down a pump impeller and NOT seeing a decrease in current draw really says the pump is not causing the current draw in the first place. It really doesn't make much sense. There should have been a drop. Ron [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Abnormal high vibration readings in a 3000 RPM centrifugal fan
Registered Member My bad, it's 30k CPM... 500Hz.... 10x? Any side bands? [ more ]
Registered Member I've seen something similar, There's a reduction in the amplitude... Well the folded paper acts as a mechanical "filter" for high frequency (in this case is not good enough try more folds or a credit card, to measure the low frequency content) but this result is pointing to high frequency overloading the sensor well this still bad news on your bearings, in your last FFT there's a lot of activity around 30kHz what's that? as a learning exercise try to measure the acceleration waveform at... [ more ]
Registered Member I am very grateful for the help and suggestion received so far. I have attached a screenshot with different readings as suggested. With a folded paper in between sensor and bearing housing and Fmax value set to 240000 CPM, the overall vibrations reading shown is 3.18 mm/s. The transducer is of 100 mV/g sensitivity. My understanding based on above comments, is that this is a sensor overload/saturation issue and it would be ok to run the fan under current conditions. Please correct if I am wrong. [ more ]
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Welcome to AMPForum help
BREAKDOWN MAINTENANCE POSTING BOARD
Registered Member I think it would also be useful as part of your site breakdown strategy that you have a management policy that every equipment breakdown that impacts on production is investigated using a Root Cause Analysis process that not only identifies corrective actions to get you back to where you were before the breakdown occurred , but also preventive actions that will prevent the breakdown or similar types of breakdowns from happening in the future [ more ]
Registered Member I think it better for newbie in maintenance field. My opinion about breakdown, if equipment breakdown it might be to restore back as soon as possible in the system by maintenance. But equipment have chance to failue as the same cause if reliability engineer's do not something. So, reliability engineer's must do something and economically concern as Josh saided. [ more ]
Registered Member First, where does or for which equipment does breakdown maintenance or run to failure strategy is applicable and economically viable option to do so? [ more ]
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Welcome to AMPBook and Article Discussions
Cá cược Liên Minh Huyền Thoại là gì? Ở đâu uy tín?

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Asset Condition ManagementPosts About vibration/alignment/balance
Shaft Runout Tolerances
Registered Member Dear, I also have a case about the runout check on a long shaft of vertical multi-stage centrifugal pump ( 4m length and 40mm shaft diameter for the area of impeller fit). This pump never was put in service before. Recently due to other issue found on other sites, we disassembled this pump to do a comprehensive inspection , meanwhile, found the runout is out of tolerance ( max. TIR found at shaft end is 0.18mm, where is for 1st stage impeller fit. ) Although I know that for this kind of pump... [ more ]
Registered Member http://www.easa.com/sites/file...R100-2010_1010-1.pdf page 6 http://www.roll-kraft.com/site...nspection-guidelines http://www.flowserve.com/files...t_fis159_slm6200.pdf page 3 Here are a few resources that show same tolerances as what has been posted Dave [ more ]
Registered Member Is 0.5mm coupling hub run out is acceptable for soft coupling? As per my knowledge the hub run outs should be less than 0.05mm. What is allowable run out for pump coupling hubs? [ more ]
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Reliability Engineering for MaintenancePosts about Capital Projects
Bearing Conversion Charts - AFBMA to SKF
Registered Member Dear Ahmed, Thanks for your support. Could you please send your E mail address on alpeshp@essar.com [ more ]
Registered Member Hello All, SKF offer a conversion guide at http://www.skf.com and http://www.aptitudexchange.com If any of you need to convert bearing designations to SKF, I will gladly have them converted for you just e-mail me your lists for conversion. [ more ]
Registered Member A tool that would be handy for you is the Bearing Expert program which contains over 1 Million Bearings. Can cross reference by part number, dimensions, bearing type, manufacturer and AFBMA number. Also contains over 200,000 bearings fault frequencies. http://www.reliabilitydirect.com/vibrationmeterproducts/vibfrequency.htm [ more ]
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Asset Condition ManagementPosts About Motor Testing
Number of Rotor Bars and Stator Slots!!
Registered Member Hello Experts, Can someone point me to a resource from where i can know the Number of Rotor Bars and Stator slots ? Of course ABB does not wanna give it. TIA, VinMan [ more ]
Registered Member Hello, You have discussed using the vibration spectrum to identify the rotor bar number but could you use the current spectrum to do estimate the rotor bar number? Also, Aditya, please can you explain how once you know the number of rotor bars it is easy to estimate the number of stator slots? Thanks! [ more ]
Registered Member You're welcome. I should clarify, the last paragraph of my last post referred to rotor slots. THMotorMan's post applied to stator slots. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Balancing shop floor operating and testing speed
Registered Member For a low speed balance, i.e., a rotor with rigid behavior, I do not understand high speed variation. The rotor is balanced as a rigid body. High speed (if meaning similar to that in ISO 1925 for high speed balancing) does not apply. [ more ]
Registered Member Then low speed balancing and high speed variation ? [ more ]
Registered Member As I read, your customer asked you to verify the balance measurement at speed. This would not be technically proper. One of the old ISO 1940 (as I recall) had some comments regarding this. Measuring at speed (often) will not produce a valid measure of a low speed balance, particularly insitu if this were to be the case. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Inboard - Outboard ??
Registered Member Then on verticals: what do you use? Using numbers; Mtr top brg = 11 or 1H or ?...? On Horz I use: Mtr ODE Horz = AH On Vert I use: Mtr top in-line w/flow = A1 I've found this combination of a & n to work quite well allbeit not he only system that works and works well. In addition I post engineering files available for all that have photos of all equipment along with the machine sketches and point ID's as well as some of the reports containing such info and block sketches. But for the... [ more ]
Registered Member We ask 5 of our men which bearing they considered to be the inbd, and otbd, and all were confused. This was on an overhung fan, so this is why we adopted the number method. Much easier to understand. Rod [ more ]
Registered Member I think you just have to say inboard and outboard to what - I have always used the drive exchange. So a jackshaft bearing can be both inboard the the motor and outboard to the fan. [ more ]
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Welcome to AMPBook and Article Discussions
Vibration Analysis Level 1 (or 2) Practice Question Q 45
Registered Member Jake, Thanks for the chart. I've comments that might be useful for some readers. There is a fundamental difference between the two waveforms (in Jake's post) which is physics. To explain this, let us use a third illustration. [source: https://www.researchgate.net/f...ia-18_fig1_262450664 ] Jake's upper plot is the amplitude (elevation of a point of the string) in the y-axis versus the location of points (examples are A, B, C, etc) along the length of the string on the x-axis. So here we look... [ more ]
Registered Member Dear colleagues here a Vibration poster that might be of your interest. ( no cost to download) https://reliabilityweb.com/steal-these-graphics [ more ]
Registered Member Hi, here’s a good visual of exactly how to find the period or frequency of any graph. [ more ]
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Asset Condition ManagementPosts About Lubrication and Oil Analysis
Greasing shielded bearings ????
Registered Member Lee, In answer to your question about sealed and shielded bearings. Sealed bearings typically have rubber seals on each side. These seals make rubbing contact with the inner race, there is no gap. Everyone agrees that these can't be relubricated. They are normally only specified for harsh environments because the rubbing contact of the seals actually shortens bearing life, so they will not last as long as a shielded or open bearing in a good environment. Shielded bearings have metal or hard... [ more ]
Registered Member David We have three deep well effluent pumps in which we replaced the upper plain bearing for a flanged SKF bearing. The bearing is 2RS however the housing has a grease nipple fitted to which we fit a 6mm tube with a nipple at the assembly top plate. The path of the grease is into the bearing and out through the rubber seals. I understand how greasing outside of 2RS bearings would not allow grease into the bearing. In our case the force of the grease slightly distorts the seal but we know... [ more ]
Registered Member Some info you may already be aware of: - AFBMA number is provided on the nameplate of motors. - AFBMA Suffix PP stands for double shielded (i.e. 65BC03 JPP3) and suffix EE stands for double-sealed (i.e. 65BC03 JEE3) - Manufacturer p/n's often identify seal or shield. For SKF it is ZZ for double-shielded and 2RS1 for double sealed. All of the shields I have seen are metal. Seals by their nature require a rubbing contact so they will usually be at least partially rubber. [ more ]
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Asset Condition ManagementPosts About Lubrication and Oil Analysis
Shell Grease Compatibility
Registered Member PAULENGR-very well stated. I agree that the Mobil Polyrex product is the most universally used motor grease and is suitable for all but the most extreme applications. As for compatibility I agree that the newer formulations have better mixing properties and the old grease compatibility charts might not reflect current practice but in JAXN14's case I'm not sure if he is willing to take a chance. If it was me I would gradually switch to the Polyrex product when changing bearings and/or motors... [ more ]
Registered Member MOST motor bearings are greased with a high temperature non-EP polyurea grease with a base viscosity right around 95-100, NOT lithium based. So right off the top I'm suspicious that you're using the wrong grease system, not just an odd viscosity. The vast majority of motor manufacturers and motor rebuild shops as a consequence use Mobil Polyrex EM or Polyrex EM 3 and nothing else. Once in a while this gets them in trouble with the high pressure roller bearings where a high temperature... [ more ]
Registered Member Does that mean ISO VG220 is suitable for motor bearings? cause from what I know typically ISO VG100-150 is preferred. What are the consequences if higher viscosity base oil chosen? What do you mean by overkill? pricy? and can you please define "normal" application? [ more ]
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Asset Condition ManagementPosts About Asset Condition Management
TREVI TESTING for RELIEF VALVES
Registered Member Thread lifted 1) Pre test defines whether or not the PSV is in such a condition it works or not. This can help give you a good historical view of the valve. i.e Is it neccesary to remove the valve every year if the valves operates and by the eye seems to be fine ? 2) Online testing has a economical advantage. I do not prefer the Trevi test equipment. I prefer the ventil preventtest or metrus Teson designed EQ for this purposes. They are more accurate and the tests are automated. Our company... [ more ]
Registered Member I have 2 clarification questions: 1) Do we really need to do the pre-overhual test and for what purposes? 2) Under what circumstances or purposes do we need to do online testing for PSVs such as Trevi test? [ more ]
Registered Member Irshad, Without going into the acceptability or otherwise of on-line testing for non-steam applications, I hope you agree that on-line testing cannot manage some of the failures modes in any safety valve. We use the term 'coverage factor' to describe the proportion of failure modes to the total managed by a given test procedure. On-line testing can never have a coverage factor of 100%. With due respect to what EPRI or other learned bodies say, there is no reason to ban on-line testing of... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
HIGH AXIAL VIBRATION
Registered Member I'm not satisfied with the solution, anyhow it is a good case study tho. regards, [ more ]
Registered Member Glad it's sorted. Did ya bump test the pedestal? The probable scenario is that you have an axial resonance at or close to 1x. The vibration may return as the impeller becomes fouled again. [ more ]
Registered Member I wish I had a dollar for every time a system didn't react like the text books said it should. This is the same reason it takes years to get good at this job. One could pay someone to come in and do a modal analysis and possibly explain the axial component. It is solved and most, if not all, companies will not spend the money. Call it good and move on to the next issue, there is always one! [ more ]
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Asset Condition ManagementPosts About Motor Testing
What is the cause of motors not running at Magnetic center
Registered Member I agree with Dave and Walt. The magnetic centering force of a motor rotor is very weak. I have preached to customers that if you have to make a choice between locking down a rotor axially off magnetic center, or moving the rotor where the shoulder is very close to the bearing, then choose the former. Many times the motors are not on level or have soft axial stiffness style couplings. The forces don't have to be high to start the oscillation. This same phenomena occurs in motors larger than... [ more ]
Registered Member I agree with David for some situations. I have noticed this effect with boiler feed water pumps that use disk-pack shaft couplings. The motor mass and coupling's soft axial spring form a simple spring-mass system. Excitation is from pump flow turbulence, but not at a single excitation frequency. Walt [ more ]
Registered Member As Pete, and Jank indicated above, axial movement of a rotor in axial direction for a sleeved motor could be modeled by a weak spring and mass. Let me propose an idea as far as mysterious slow force is concerned. There is no slow force! Instead, there is a very low stiffness system with low resonance frequency and RANDOM FORCE NOISE ( flow, coupling, loading, etc) causing relatively large movement of the rotor at resonance frequency. If type of force, such as impacting, is periodic then... [ more ]
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Asset Condition ManagementPosts About Asset Condition Management
Overhung Fan assemblies Which bearing should be fixed and floating?
Registered Member Re: Overhung Fan assemblies Which bearing should be fixed and floating? [ more ]
Registered Member Please note that my email address is NO LONGER rod.bennett@bluescopesteel.com I have mostly retired and my email address is NOW rodjbennett@bigpond.com [ more ]
Registered Member Anantharaman, What you are saying sounds correct. It is normal to fix the bearing handling the higher radial load. Refer Plant Services article http://www.plantservices.com/articles/2008/012/ [ more ]
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Asset Condition ManagementPosts About Motor Testing
Megger Test Fails to Detect Winding Failure
Registered Member (Posted on December 8, 2008 @ 11:13 PM) I said I would post the results of the capacitance measurement on the motor after the rewind is complete. So here are the numbers: 1) Measured with Fluke 87 multimeter: 12430 pF per phase 2) Measured with a megger @ 1000 Volts: 11900 pF per phase 3) Measured with a megger @ 5000 Volts: 12300 pF per phase It can be seen that the capacitance to ground is a true constant unlike the inductance of the winding that varies over several hundred percent. In the... [ more ]
Registered Member It is a fact that experimentation is rarely seen on this board. I think it is fair to say that the working paper posted by quoted author on October28, 2008 at 8:29 failed completely from theoretical point of view. There was not one single result correct. The second paper, posted on December 9, 2008 at 01:11 AM, contained both the theoretical part and the practical experiments. So let’s have a look, for a change, on the practical results. I would really recommend reading this paper, because... [ more ]
Registered Member Thanks TestTech, I'm glad that you appreciated my contribution. Looking at the thread, I can see why you used the term battlefield, although I didn't intend to contribute to that type of environment. My goal was to get to the bottom of the question and also try to make the conclusion obvious to others, although sometimes I get sidetracked and sometimes I make simple things sound more complicated then they really are. I'm glad you were able to sort through all that to find the right... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Generator sleeve bearing shaft vibration probes X&Y are showing different values.
Registered Member Your cursor is shown at 25 Hz (1250 cpm). Was the generator synched at the time? Can you expand the region from 0 Hz to about 100 Hz so we can get better definition of the frequencies that are shown? I'm interested in knowing if that DE is showing 1X and 2X and the NDE only showing 1X. Also, what type of coupling is at the DE of the generator? [ more ]
Registered Member Dear Mr. John, I understand the difficulty now, I better be posted in .pdf format. Anyways an experience in this forum. Please find the attached pdf file. [ more ]
Registered Member As you can see from the image I've attached I can't make out the two lowest spectra from your original post. This isn't your problem, just one I encounter on this particular forum where the original post overlaps the forum header information. Can you post the data as an Adobe attachment? I would specifically be interested in knowing whether the data showing the 2X is the DE or NDE of the generator and also if the generator has a coupled exciter. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Velocity and acceleration in vibration analysis
Registered Member IMO, seek out knowledge from someone who knows more than you do. “The more I learn, the more I realize how much I don't know.” (Albert Einstein) [ more ]
Registered Member It's misfortounate the poor guy got faced with all the turbo machine PhD type guys in looking for an answer. the instrument you have sounds like either a skf quick collect or a Xmas machine advisor Vibe pen, both instruments mainly just tar an overall reading of velocity and enveloped acceleration, you regally need an instrument with a fft display to be able to put in context what you are looking at. The skf quick collect sensor if you have it has a facility to generate a very simplistic... [ more ]
Registered Member Dear Mr JAMESK, Wellcome to this forum.you have plenty of explanation for your question and how you take it all.? when you collect vibration data using any vibration data collector you will get many unwanted noise along with useful data what is required for fault analysis.The problem is that the identifying signal (useful data) is usually drowned out in other noise emanating from the machine. Hope you know about FFT spectrum analysis,where in rotating machine faults are identified for... [ more ]
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Reliability Engineering for MaintenancePosts about Reliability Engineering for Maintenance
High Amperage problem with centrifugal pump motors
Registered Member The ARVs (Automatic Recirculation valves) for four of the parallel running pumps were observed passing, causing high capacity flow across the pumps. Therefore leading to high amperage problem. We are presently investigating the reason for the cause of ARV problem. Thanks for all of you sharing your ideas. Looking forward for more suggestions... Good day.... Mohammad [ more ]
Registered Member Is the motor correctly connected in star/delta? [ more ]
Registered Member Makes sense, running two pumps in parallel will increase the back pressure since this is a function of the flow. Try throtling a valve (not gate or block) in the discharge, probably you have a control valve somewhere? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
High Gravitational Envelope (gE value) in motor bearing
Registered Member I agree with OLI listen to it with a stethoscope. No information on the motor drive train and i see the bearing is an NU type... maybe application related? [ more ]
Registered Member I don't mind making calls on brand new motors, on the contrary. Is it on VFD or VFD close by? It may be slight change in operation position that made a move in to a damaged operating zone or infinite other reasons. Do it sound like a disaster with stethoscope, screw driver or yellow handle analyzer? Call it then, maybe as planned as suitable. There are no worse than having a fail sitting on data indicating that is the case and not reporting, minimum issue a warning report to swap brg if stop... [ more ]
Registered Member You have a pretty raised peaking level on that time wave for some peaks almost 8 g? also that fft is still in Velocity if you press 'A' on the keyboard should show in acceleration. [ more ]
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Reliability Engineering for MaintenancePosts about Reliability Engineering for Maintenance
Maintenance Costs Industry Standards
Registered Member Joe F, There are two methods used for this purpose. The first is Maintenance cost as a %age of Replacement value, the second uses the ratio of cost to production volume or value. Many errors can occur with these KPIs. Definitions of what goes into the 'cost' figure vary, as also in computing Replacent Value. Production volumes and values are dependent on market fluctuations, causing swings in the ratios. Cyclical costs, such as Turnaround costs have to be spread over the cycle. If all this... [ more ]
Registered Member So what do you think of the figures I gave above? Are these figures reasonable for your precast concrete plant? A very long conveyor system, right? Is it Dusty? [ more ]
Registered Member We make Precast Concret panels for building construction. The cast is done on a rolling bed over 600 feet long. [ more ]
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Asset Condition ManagementPosts About Asset Condition Management
High 3X vibration in uncoupled condition
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Registered Member have you perofrmed phase analysis to look for cocked bearings? collect phase data at 4 points around the bearing in the axial direction. if the bearing is cocked, the phase shift will be about 180 from top to bottom or side to side. Balancing and aligment attempts will not make any change to the phase [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Does it really matter to set a probe at - 10.0 VDC?
Registered Member Is it? In short #3. https://en.wikipedia.org/wiki/..._displacement_sensor [ more ]
Registered Member That sensor has a rather different application. [ more ]
Registered Member There are other brands in the world also you know but yes that is likely one of them. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
𝐑𝐞𝐜𝐨𝐠𝐧𝐢𝐳𝐢𝐧𝐠 𝐕𝐢𝐛𝐫𝐚𝐭𝐢𝐨𝐧 𝐏𝐥𝐨𝐭𝐬 (Cat II Question)