Skip to main content

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 ]
See all 27 replies...

Share This Post

Asset Condition ManagementPosts About Motor Testing
What causes a motor to draw higher than normal amps
Registered Member ❤️
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 ]
See all 9 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
Machine age vs vibration level
Registered Member A bathtub curve graphically relates three types of failure: early, random (constant failure), and wear out . Manufacturing and material defects typically result in early, rapid failure of objects: that region of a bathtub curve is called infant mortality. new machine also can fail as above infant failures. So age /vs how the machine is operated with respect to its design /vs maintainability of the machine FFT Spectrum gives you instant healthiness of the machine so no need to trend the... [ more ]
Registered Member Your results may vary! If a pump is built with proper parts balanced and has the correct shaft clearances and runout it may exhibit lower vibration levels than it the new baseline. I was just involved in a pump that was rebuilt 4 months ago. It was installed without motor shims. When the coupling failed four months later, it was found to be over .080 high. The alignment was corrected and the levels were down but not as far as I would have expected. The gross misalignment had taken it's toll... [ more ]
Registered Member But in our case Malcolm, age is getting to be more of a factor, especially when we consider buying green bananas. Best regards, JGW (BN-MDS 100% retired) [ more ]
See all 8 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
Beating phenomenum at Conveyor Drive System with Hydraulic Coupling
Registered Member check for soft foot issue at motor though u had said precisely aligned coupling.u should check the soft foot both dynamic condition as well as static condition. [ more ]
Registered Member As using Voith coupling, it is easy to determine the suitable hydro coupling specs for the machine. You just need input speed & motor kW (Power) & refer to the table provided in their website. I also experiencing same experience as you, high vibration for conveyor drive system & spectrum shows peak at 1X RS. I am not concern about the beating in the spectrum. For my case, the problem is only unbalance issue cause from the hydro coupling itself (eccentric I guess). I am using... [ more ]
Registered Member You can see in this attached picture that there is actually beating in CV029 with 3000 T/H (50% of design load) Vibration spectra seems like amplitude modulation with 4000 T/H because two frequencies are getting far away from each other. Greetings [ more ]
See all 19 replies...

Share This Post

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 ]
See all 17 replies...

Share This Post

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 ]
See all 12 replies...

Share This Post

Welcome to AMPBook and Article Discussions
Cách làm thầu bóng đá cho mùa euro 2020 kiếm trăm triệu

Share This Post

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 ]
See all 16 replies...

Share This Post

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 ]
See all 10 replies...

Share This Post

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 ]
See all 7 replies...

Share This Post

Reliability Engineering for MaintenancePosts about Reliability Engineering for Maintenance
Calculating Plant Availability
Registered Member From my days in power generation, maybe these basic availability statistics would be helpful. Over a given period for a generating unit: Availability Factor = ratio of time on line to total time in the period. Capacity Factor = ratio of actual output to output that a unit can achieve at rated capacity (sometimes called maximum dependable capacity). Available Capacity Factor = output that could have been achieved, if desired/required, to the output that a unit can achieve at rated capacity. [ more ]
Registered Member The difference between the two might be called equipment availability vs. system availability. Could it not depend at which level you are measuring? [ more ]
Registered Member Ecky, You say: Why so? The definition of availability is just that; that the item is ready for use if required or it is already in use. I don't see the need to redefine availability because of a problem that you believe exists. Such a move would not help you with your original problem either, since you still have to account for slowdowns as well as quality related issues. In my view it is better to get a clear picture if what each term means and use the right one for your purpose. There are... [ more ]
See all 21 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
The sawtooth vibration behavior occurs after steam turbine running up to normal speed
Registered Member I have attached Exhaust Temperature & Inlet Steam Flow Curve of a Single Stage (Curtis) Back Pressure Steam Turbine where effect of Governor Valve movement on Exhaust Temperature is more evident. [ more ]
Registered Member Hello lux You have mentioned no obvious relation with Differential Temperature b/w Upper & Lower Casing and also you have mentioned Casing Temperatures of 400-410 Deg Celsius. May I ask how Casing Temperature is measured ? You have mentioned current behavior is not related to Process Loading. May I ask if the Turbine Inlet Steam Flow remains constant from the time Vibration fluctuation starts till the time it is vanished ? During Startup Temperature within Steam Turbine changes sharply... [ more ]
Registered Member Hello Dear All- Thanks for your kind comments above. For the casing expansion----Actually this was measured duirng the commissioning (at the beginning of this year), didnot find an uneven expansion from the readings of several dail gauges at that time. Also as I mentioned above, the vibration behavior is not related to starting mode. Even for hot start ( Time interval between shutdown and restartup is less than 1 hour), the temperature of casing compared to normal operting basically was same... [ more ]
See all 15 replies...

Share This Post

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 ]
See all 66 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
Difference betwen a velometer and an accelerometer
Registered Member If you go to the nitty gritty lo signal you should look at HOW more output is produced. Piezo material produce noise, if you just make higher amplification and not higher raw signal you also amplify the noise. Moving coil velocity probes are better to amplify as the noise produced in the sensor is much smaller. To get 1V/mm/s is no problem with very good long term results. Olov [ more ]
Registered Member I was simply comparing the values of an acceleration or a velocity signal. I was attempting to point out that in the lower frequency ranges, for a given vibration, you have "more" velocity signal than acceleration. As many of us have studied in classes, acceleration tends to attenuate lower frequencies and accent higher frequencies, displacement is opposite, and velocity is more even across a wide band. This means that at lower frequencies, you are trying to measure a naturally smaller... [ more ]
Registered Member Michael, you mentionned signal to noise ratio in your latest comment. What would be an acceptable range for a monitoring system for the full scale we want to monitor. For example, if we need to check from 0 to 10mm/sec peak, is it OK to have a signal from 0 to 10mVolt? What is typical? Thank you. Charles Auger [ more ]
See all 17 replies...

Share This Post

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 ]
See all 22 replies...

Share This Post

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 ]
See all 9 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
Key length calculator?
Registered Member Wonder if I put a disclaimer in there before uploading that years ago... Gald it's getting some extra mileage. [ more ]
Registered Member Length x width x thickness x 128.8 will give you your key weight in grams. We use this formula to find the half key weight when balancing rotors. I would think it would work to find the amount of key needed to fill a keyway. [ more ]
Registered Member Here are the results for cutting the simple key, which is half the exposed keyway, the full key and the stepped key. [ more ]
See all 21 replies...

Share This Post

Welcome to AMPBook and Article Discussions
Cá cược Liên Minh Huyền Thoại là gì? Ở đâu uy tín?

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
Who is a best bearing manufacture in the world?
Registered Member As far as radial ball bearings for electric motors or pumps-SKF, FAG, NTN Pillow Block Bearings for Fans: Standard & Medium Duty Ball-_Sealmaster Heavy Duty Ball-Linkbelt or Fafnir (Fafnir doesn't make an expansion) Spherical Roller Bearing--Solid Housing-Dodge Imperial Series Spherical Roller-Split Housing--SKF [ more ]
Registered Member I have no idea what is the right awnser, but for pure quality I tend to trust Japanese companies the most so in bearing that would be NTN and NSK. My bias comes from automobile companies but I don't know if it can be applied to all sectors. With that said, service is very important for me and SKF are always glad to help so it's my go to company. And like others have said, with good maintenance any bearing from a big company will last a very long time. [ more ]
Registered Member Going through the list. I guess Pioneer and Kingsbury will make it top for huge babbitt bearings. [ more ]
See all 14 replies...

Share This Post

Reliability Engineering for MaintenancePosts about Capital Projects
How to set Magnetic Center of the motor
Registered Member It's not unheard of for 2-pole motors to oscillate axially when uncoupled. Two factors drive this behavior to be more common in 2-pole motors than slower motors: 1 - 2-pole motors tend to have weaker centering force than slower motors due to fewer vent ducts or no vent ducts. 2 - 2-pole motors tend to have stronger air-related forces due to axial fan design. You can often see this by temporarily blocking off air entrance on double-end ventilated motors and looking for change in rotor... [ more ]
See 1 reply...

Share This Post

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 ]
See all 11 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
sleeve bearing scraping and blue-check / dry-roll check: common misconception
Registered Member I believe these date back to the 70's. The first analysis of the stiffness properties is more recent. I don't remember your application. Some have been used on exciters. [ more ]
Registered Member Sorry, I missed the "socket" part. We have nothing like that. I take it you have had good experience with those? We do have one application (main feedwater pumps) where we installed new-fangled "fluid pivot" bearings from Pioneer. Somehow uses oil on the back side of the pad to support it rather than mechanical contact. http://www.pioneer1.com/engine...id-pivot-10-reasons/ You may remember that we called you up after we installed them because our vib jumped up. I think your initial idea was... [ more ]
Registered Member That's a reason for the ball and socket design over the ball on plate point contact, design. [ more ]
See all 44 replies...

Share This Post

Asset Condition ManagementPosts About vibration/alignment/balance
Two-Plane vs. Single plane spin balancing
Registered Member Zman, I agree with you 100% on your theoretical scenario. Cement plant ID fans are a very good example of this. Checking phase difference at the start should be standard practice. If little phase difference and similar amplitudes, then yes, single plane will work. If not, nod a two plane balance. [ more ]
Registered Member Dave, Well put. There are many reasons for the vibration to appear at multiple harmonics as well as broad band noise that can be for no other reason than a high imbalance force driving the system non-linear and exciting natural frequencies, causing impacting, etc. The 1x peak should still be predominant, but balancing can drive down all of the other energy very often. For any field tech that has been there, this has got to be obvious. I was stuck on a weekend balancing a 5KW gas turbine... [ more ]
Registered Member Here is some examples of how I relate to a single or a two plane balance. Have seen large and small fans with at least 4 harmonics of run speed be purely imbalance. Structure/base makes a big difference on how sensistive a machine is to imbalance and what type of vibration signature to expect. Have some manufactures that think just plain C channel makes a good base. The motors on these machines are 250-300HP 1800 rpm turning a rotating mass of 2500lbs with vibration levels on the motors over... [ more ]
See all 41 replies...

Share This Post

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 ]
See all 35 replies...

Share This Post

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 ]
See all 4 replies...

Share This Post