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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Screw Compressor Motor Overload Tripping
Registered Member Farhad, Apologies for the delay in replying. I have a couple of more questions and some things to possibly check for potential problems. 1. Is the Oil removal unit strictly for removing oil, or also a dryer? (I would recommend a dryer be installed if one isn't there) 2. Have you considered a receiver upstream of the oil removal unit (dryer)? 3. Does your receiver have a timed drain to remove any condensate buildup? I would check the receiver for possible condensate buildup. Verify that your... [ more ]
Registered Member Hi! Michael. First of all thank a lot for providing your input. I have attached schematics of system which I will be frequently referring in answering your queries below: First of all, please understand normal operation first. During normal operation, 3 out of 4 C-4202 ABCD compressors are put in operation to maintain receiver tank pressure near 7 bar. If one compressor out of these four is out of service for maintenance and we are struggling to maintain header pressure near 7 bar then... [ more ]
Registered Member All of the compressors should be seeing the same pressure at discharge if all valves are aligned correctly. I have a few questions to help troubleshoot. 1. Are all of the compressors set to the same discharge pressure set point? If so, do the pressure transducers or gauges all read the same? 2. Are these compressors variable speed or variable capacity? If so, are they staggered to have load picked up and shed in a sequential manner as system demand changes? 3. Do you have a system receiver... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
BATTERY BLAST DURING ENGINE START UP
Registered Member Thanks to all for replying. Many factors causing that problem. Low Electrolyte level, Charging with High current which deform electrode,Overcharging, Wrong replacement ( SMF is not compatible with application and area) of battery during last replacement, problem resolved with replacement of adequate type and size batteries. working fine so far.. Thanks [ more ]
Registered Member yes valve, svanels shared same as what i am talking about. [ more ]
Registered Member svanels shared a very good reference [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Throat Bush Clearance and Stuffing Box Pressure
Registered Member If the machine is multistage pump, then you need to have the following to solve your problem 1- the first stage and second stage impellers are on the seals chamber area. And the last stage (high pressure) is in middle. If your last stage impeller is near to seal chambers ( not middle) then you should maintain 0.7 mm throat bushing clearance and add libyrinth ring on mechanical sleeve with clearance 0.7 . Check pump cross section to see the impellers arrangment. Again i assume you have high... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Bearing current damage on NDE bearing due to bearing current
Registered Member First time on this blog and I see these postings are a few years old, but here goes it anyway: I reviewed the pictures and agree you are experiencing electrically induced bearing failure. Incidence rates of bearing failure on VFD motors is at least 60% by 2 years and only continues to climb from there. It is a well-accepted and pervasive problem that particularly plagues operations that run 24/7. The following information is based on long-term field and lab studies over 30 years. 1)... [ more ]
Registered Member Good point. We experienced fluting to varying degrees on 9 75hp Extruder motors. Installed a couple of ground rings and then had a rep from ring manufacturer test our motors and he showed we still had problem due to bad ground. Inspection found some ground lugs weren't tight but after fix we still had shaft voltages so all motors got rings. I check voltage levels every 3 months and shafts have to be cleaned regularly due to dirty environment. 1 motor has ring mounted internally but I worry... [ more ]
Registered Member I too would like to add some additional experience....Motor 450HP 900RPM 480Volt 3 phase with insulated shafts on both ends, intermittent duty, megged over 1000megs between bare shaft and insulating material on both ends, shaft grounding ring, both bearings have oil not grease and still have electrical fluting. The suspected root cause is the cables from the VFD to the motor not having proper shielding. Had over 300 volts from the rotating shaft to ground! Best to measure/test to better... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Root cause of a broken gear shaft
Registered Member Kevin Ku, Whats the current status of these gearboxes? Has there any other shaft failure occured during the last 15 months? Regards, Mohammad [ more ]
Registered Member This cut looks like a cup,it may be due to stress concentration from the inner race fit with the shaft regards mahmood el.nagar nubaria power station Egypt [ more ]
Registered Member Has there been any machine work done to the bearing fit on this shaft? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Coupling Bolt Failure
Registered Member Poor coupling choice-period. On this type of coupling arrangement, there has to be a consideration of a way to keep the two spool halves in alignment-especially at speed. If the " insulating " material in the bolt holes loses it's integrity for any reason, it will allow movement of the two coupling halves. With the affect of any of a number of variables (misalignment,thermal growth,hydraulic/pressure cycling,etc.), a ratcheting affect could cause bolt stresses enough to cause bolt failures... [ more ]
Registered Member I'm so sorry too late for All. - lap test - result failure mode is Brittle Overload - OEM - this is the first design for insulation bolt ,it's recommended from Pump OEM. They don't have experience for this case. - Maintenance Program - We create new program follow All advice, Inspection and re-tighten Bolt every CI(1 year). Use CBM program for visual inspect coupling slip every 1 month, Replace the insulating parts every MI (3 year) thank you and best regards AS [ more ]
Registered Member Yeah, the question is for the original poster. Minimal maint readiness before first prod is at least setting up PM program based on OEM recommendations. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Shaft worn out
Registered Member Correct responses above. The result is called "fretting", leaving a brown deposit on the mating surfaces. In this case it has gone beyond fretting and started to wear the shaft. After evaluating the interference fit between inner race bore and shaft, next time you mount a bearing in this application put a mark on the shaft and a corresponding mark on the inner race. This way, when the inner ring starts walking, you can catch this condition early before it ruins your shaft. [ more ]
Registered Member Kevin, Do you have vibration data associated with the presented cases which could be posted? Was this damage sdiagnosed based on vibration data? Thanks, David [ more ]
Registered Member Kevin, i also had similar experience, these type of occur when we have frequent replacements of brng over the same shaft. so i suggest that brng loctite should be used and while assembling it shd be with brng induction heater so that after getting cooled proper fits will be obtained considering the tolerance limits. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Steam turbine differential expansion
Registered Member Hello Turbine Engineer, Normally for a working turbine, turbine differential expansion should not change during turbine normal running. This is a protective measurement during start-up and shutdown. if this happened gradually, wearing of rotor trust bearing shoes can cause such issue but for ensuring that it is better, when Turbine is cold put turbine on turning gear and check the differential expansion measurement. If it is not zero this could be the reason and shall be reset to zero. Hope... [ more ]
Registered Member Many big turbine are running on date without any type of lubrication in the sliding pedestals and sole plates. Vibamster [ more ]
Registered Member Ditto on lack of or improper pedestal greasing. Especially if the turbine has had a satisfactory operating history (for the most part). [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Centrifugal pump motor overload tripping
Registered Member Just to add one more thing. I have analyzed FFT spectrum of pump which is also giving clear signs of pump cavitation. Raised floor at and beyon VPF. [ more ]
Registered Member Plz find the snap attached. Regards, Syed Sajjad Ahmed [ more ]
Registered Member Hi Ahmed, Can You share eroded impeller/casing snaps to understand the severity as well as Pump performence curve. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Screw compressor, rotor rubbing failure
Registered Member hi dear all; i need compressor clearances for aerzen vm 45.please help me thanks [ more ]
Registered Member OK, now there is much more info available. In most similar cases the cause is inappropriate lubrication (wrong oil selection, old oil, metal pieces in oil, pump damage, unclean filter, congested oil pipes). Is the lubrication system external? The other possibility is that journal bearing ring is too tight regarding the shaft. I suspect that in the beginning there was a lubrication issue. It caused the surface's (shaft and ring) thermical and mechanical damage. At that time the overhaul guy... [ more ]
Registered Member Yes, male rotor shaft of drive side was worn out severely. And this shaft color also was changed by thermal effect and was bend. But I'm not sure which one is first. Because if journal bearing was not good, shaft and packing could be rubbed each other. and if rotor rubbing was occurred, it effect to bearing and shaft packing. Oh, I'm sorry there is one i missed to explain at first. Before this trouble, i mean after overhaul, this machine was start up and stop 8 times for 3 months. It makes... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
VERTICAL TURBINE PUMP -2 STAGE FREQUENT FAILURE OF SHAFT BUT DIFFERENT LOCATION
Registered Member Hello. We have similar column pipe bolt sheared. Shaft bent.Bottom neck ring to impeller stuck causing cold welding. But unable to find the cause. No overload motor trip. Few possibilities are 1) Column pipe bolt loose causing offset of bowl assembly. 2) Pump operating at closed shutoff. Recycle line PRV failure . 3) Low clearances of neck ring to impeller. Foreign particle stuck. Please provide your inputs. [ more ]
Registered Member Hi CBM, Dave Reynolds has attached some very good info on breakages and in Dave's literature there are images of misalignment breakages with ratchet marks, this breakage appears very similar with fine ratchet marks around the circumference of the shaft breakage, if you are still trying to solve this let us know and I’ll ask our metallurgist for an opinion and if it is of use we can post his comments here to assist, regards Rob S [ more ]
Registered Member The double paste can be edited by the OP, can it? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Two direction axial movement of steam turbine shaft
Registered Member Quotes from posting: (i) Allowable tolerance = 0.25 mm max. (ii) so we found a deep (appprox. 0.5mm) cut in the inactive side thrust collar Those two add up to give about 0.75mm of clearance and this doesn't take account of any wear to the thrust pad which must have been substantial - because babbitt is so soft compared to steel, I would suggest that the babbitt loss should at least equal the loss of steel say ~0.5mm - the additional axial movement due to loss of babbitt doesn't appear in... [ more ]
Registered Member Wow! - what are your thrust pads made of???? That's pretty bad wear on the thrust collar. I am VERY surprised that you didn't get any temperature increase with that sort of rubbing. How long has this been going on, when did you last inspect the thrust collar? Hope the machine is running OK now? [ more ]
Registered Member The picture looks like its the thrust disc which would be made of steel. When assembled and installed this disc would be sandwiched between the active and inactive (or normal and counter) thrust bearing pads. The pads should be faced with babbit which is much softer than steel: if there is excessive thrust loading then the babbit should wear first - is my understanding of your picture correct? Do you have any pictures of the pads themselves? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
SKF Spherical Roller Bearing Installation / Adapter Sleeve Thread Damage
Registered Member Well, That is about the next, to the best, excuse anyone could have. [ more ]
Registered Member I left that company 3 months ago, thats why i haven't replied. Checked with my friends today and they haven't faced with that problem since i've left. So looks like i am the problem... I ordered SKF TMFN wrenches before i left and they are using those tools. These are impact wrenches to tighten the nut. I think proper tools fixed the problem. By the way, we used to put lock washer with the bearing. Those days the problem was damaging lock washer tips while tightening the nut. Thats why we... [ more ]
Registered Member Serdar , Been 4 months since your post. Just wondering if you have found a possible solution for the problem. Thanks and Hae a Great Day, Ralph [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Crusher vibration problem
Registered Member I already suggested for motor pulley unbalance.Thank you very much for discussion you had with me in last two days. This forum is really helpful [ more ]
Registered Member If motor vibration has a high 1X, uncoupled, it must be unbalance of the motor or pulley. Could also be caused by a bend axis or poulley. The reason that levels are lower when coupled is that the belts 'hold down' the motor and create more stiffness. [ more ]
Registered Member Inspect motor pulley eccentricity for possible contributor to high 1 X [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cummings Fire Pump Diesel Overheating
Registered Member Just a note and some closure- I have taken the thermostat out and it has been operating perfectly since. While the engine runs it has a good operating temperature and after shut down it is fine. I have no idea why or what actually caused the problem in the first place. Until I have a problem with it I am going to leave it the way it is. I thank everyone who posted and gave alot of great info -THANK YOU [ more ]
Registered Member Mike, Just curious, was this ever resolved. I just found this thread and think it's interesting. Couple questions: 1. Is the turbo water cooled? 2. What readings are you getting for your exhaust gas temperatures under load? 3. Is there a off-load cool down time protocol? [ more ]
Registered Member MIKE, In case of our engine NT-495 Cumins make the gear box supplier has installed a plug on the outside of the tube carrying oil to the top bearing. The plug is accessible anytime. Usually during engine running , we check the lub oil supply to the top bearing by loosening the plug. We can also install a gauge there for online visual indication. The gear box is Amarillo make right angled drive. Your suspect in this regard for choking of line seems reasonable. Also, cooling water line for... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cooling Tower Gearbox Failures
Registered Member Sir, i want to know that how bearings or gears generates high frequency vib. esp more than 40Khz. is there any examples of high frequency vibration with calculations? [ more ]
Registered Member Originally Posted by rgf12: Attached is a report on a recent GB failure on one of our plants cooling tower fan drive gearboxes. It looks to me that the concentration of the failure area on the shaft side of the gear would indicate either a misalignment under load or a general overloaded condition. I'm thinking that the wear would be more uniform if it was lubrication related. Any thoughts? This is not a lubrication issue. Have seen this kind of failure before and this seems to be due to... [ more ]
Registered Member Originally Posted by Rbt: I believe part of the problems the gearboxes face is how they are started. Our plant below us, same size(14 gearboxes)when they push start it is straight to 1800 rpm. Whereas ours has low speed when started and then to high speed. They have changed out roughly 9 gearboxes during the same time period. On the gearbox we pulled out,it had an intermediate bottom bearing issue. Through the inspection plate you could see the shavings and the damaged inner race. The gears... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Failure of Reciprocating compressor.
Registered Member I'd love to Dave but unfortuantely the readings were taken by an outside contractor, and we have since parted ways! [ more ]
Registered Member It would've been interesting to see an example of vibration signature which DID provide an advanced warning before failure occurred? May be some one has one? Although, likely the impending failure would progress too fast to be captured. Stephen, can you post your vibration data? Thanks, Dave [ more ]
Registered Member Rocky R. I can't compare the old pistons to the new ones unfortunately. Yes my first opinion was hydraulic lock also. Klaus K, I assume by hydraulicking you mean hydraulic lock? It's a chiller for a solvent recovery system. The problem with refrigerant getting into the suction line is that there is a superheater between the evaporator and the suction line. The chiller was up to temperature at the time of the failure, so you would assume that any liquid refrigerant would get boiled off before... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Shaft journal wear off without wearing off of bearing pads.
Registered Member It seem from the picture which you attached the journal bearing zone in the shaft has a lot of rust accumulation there. Maybe the rust particles are agent assistance to scratch and wear the shaft in that zone. You have to analyze the oil condition perhaps has a lot of water which is reducing and effect the oil additives and composition. If you found oil is contaminated you have to find out the main source either to check gland packing system or the labyrinth condition. You are lucky you don... [ more ]
Registered Member The main root cause is oil contamination with steam. The steam is sprayed inside the bearing housing ?? The picture showed a change in color of journal , as rusted, may be combined with the low chrome material for shaft. The water molecules affects the microscopic surface of the shaft when modify the enthalpy, and change from steam to liquid. You need to address first the stem ingress into bearing house [ more ]
Registered Member i still do not think it is wire wool since the babbit is still 98% intact. small defect of 2% caused by small particle embedded in the babbit. the fact the wear occurs evenly around shaft bearing journal (at least 50mm in length) eliminates wire wool. unless the turbine is having 50mm (yes, 50MM) axial float, then wire wool is likely the cause.. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Vibration at 5X NDE AND DE V for Centrifugal Pump
Registered Member Is the pump running at BEP or away from it. [ more ]
Registered Member what was the cause of the 5X ? [ more ]
Registered Member GREETINGS WELL NOTED. THANKS FOR YOUR FEEDBACK. PLEASE FOLLOW THIS METHOD AND TRY HOW YOUR VIBRATIONS ARE INDICATING. 1. CLOSE DISCHARGE VALVE AND START THE PUMP AFTER FEW SECONDS AT FULL SPEED AT MAXIMUM PRESSURE MEASURE THE VIBRATION SLOWLY OPEN DISCHARGE VALVE AND MEASURE THE VIBRATION. IF FLOW INCREASING TIME VIBRATION RISING IT IS RELATED TO FLOW SURGES CAUSING THE VIBRATION. IF STEADY AT EVERY DISCHARGE VALVE POSITION THEN THE VIBRATION IS NOT FLOW RELATED. ALSO TAKE RUN UP AND COAST... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
ID FAN VIBRATION
Registered Member As others stated, mechanical looseness is present. The sidebands are most likely from the outer or inner race spinning. When the bearing spins in the housing/shaft, it is turning at a different speed which will create a frequency very close to running speed. Have seen worn gear couplings exhibit this same pattern. Down and dirty way of checking. Dial indicator on shaft of interest at top dead center, long bar and block/s of wood, gently pry up on shaft and record total indicator movement. [ more ]
Registered Member any other idea for this reading from experts [ more ]
Registered Member 5x?...how many blades the impeller? 1x, there is the unbalance, is clare. how many blades per impeller there is an imbalance, it is clear but, regarding the last photo, many nx armonics indicated like bearing/housing looseness... we see high 14x armonic, probably 14 impeller blades? but the sideband from 6x to 18x is look like a rotor bar problem about motor...? many things, but just my opinion [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
O ring failure in Pilot Operated Safety Valves
Registered Member https://www.slideshare.net/Tom...resentation-2015-new slide number 38, very good information, it would appear from your images that the oring melted or creeped due to excessive temperature Dave http://www.marcorubber.com/o-ring-troubleshooting.htm http://dupontelastomers.com/Pr...tails.asp?show=div04 http://www.dupont.com/products...tant-elastomers.html http://www.kalrez.nl/Products/...gGuide/extrusion.asp http://www.kalrez.nl/Products/...ngGuide/cracking.asp ... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Pump shaft broken
Registered Member Beach marks can all but disappear if the amplitude of cyclic loading is even throughout the fracture process. But the fatigue striations will remain visible under SEM examination. I do see some evidence of striations at the lower right of the first picture (Shaft 1.jpg). Beach marks presented in text books usually show the appearance of fatigue with a single point initiation. This shaft has multiple origins around the circumference. Once the fracture planes join together, the fracture front... [ more ]
Registered Member Thanks all of comments. Kestas, I agree with your comment but why i am not find the beach mark? and why the final rupture not appear close to center of surface? I taked a photo after broken about 2 weeks. Best regards, Weerasak W. P.S. I am not fluent in english, sorry if I use no good. [ more ]
Registered Member The fracture surface shows evidence of rotational bending fatigue with multiple origins around the circumference. Fatigue covers roughly 60-80% of the cross section, indicating that there wasn't a whole lot of bending forces, but enough to fatigue crack the cross section. The picture isn't color-corrected, but it doesn't appear that corrosion played any significant role in this fracture. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Gearbox Bearing Failure
Registered Member While the design certainly isn't optimum, I hope you have trained your mechanics to be aware of potential excess interference issues in bearing seats resulting in high stress concentrations. The design issues could have been compensated for in the installation process, ensuring that the bearing seat/pin was as close to flush as possible, minimizing the stress point. Craftsmanship is important in maintenance and reliability, and training is key to good craftsmanship. Turning RCA into lessons... [ more ]
Registered Member Update: Root cause of failure was found to be a combination of poor bearing seating and hoop stress causing the inner ring to crack. This poor design had a pin hole where the bearing goes on the shaft which created a localized high load/stress spot if the pin wasn't flush with the shaft. Any high/low pin position would induce stress point. Some high spots around the hole were also noticed which created "hoop stress" on the ring causing the ring to crack after cyclic loads. The true root... [ more ]
Registered Member Gearbox was in service for 6yrs, and is believed to be rebuild before by plant maintenance. Gearbox is wall mounted to the rotary valve housing itself and motor is flange mounted to the gearbox. Intermediate and output shaft have tapered bearing, the input shaft had two ball bearing and the inner bearing is the one failed. The bearing company is FBJ, made in Taiwan. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Gyratory Crusher Failure Modes
Registered Member Hello Wendy, Not sure if you are still working on this issue, only came across this posting today. I would agree with Bill on his posting with regards to potential failure causes. In my previous position, I was a Reliability Engineer with an Iron Ore operation and had a similar failure except our crusher was in operation for a number of years, not a new install (the mine was in operation since the late 50's, early 60's). During the investigation, it was noted that the eccentric bushing will... [ more ]
Registered Member Hi Wendy, I was wondering if you ever able to establish the root cause of the failure? [ more ]
Registered Member Hello All i have some problem in my site there is a lot of oil leakage from around of gyratory crusher main shaft, also after remove air blower line from crusher discharge oil from that. what is my problem?seal ring damaged?main shaft o ring damaged? pls help me [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Confusion on RCFA, RCA, FA
Registered Member Hello All, Here is my distinction between the three : Failure Analysis If we speak about failure analysis, it is right to say that we stop our analysis on the component level, or the physical analysis of the failure. We refer here to the metallurgical aspect as to why the failure occur, then the analysis stops. Example, when you send a bearing to the lab, they will check the raceway and conclude that it was fatigue, mostly the analysis stops here and the lab will recommend countermeasure but... [ more ]
Guest A few years ago I had the same doubt.I asked Mr.Robert.J.Latino(www.reliability.com,PROACT Software)for an explanation.He send me a reply which I have copied below. Thomas Purackal. ---------------------------------------------- Recently, Reliability Center, Inc. received an inquiry from one of our web visitors asking the differences between three confusingly similar Reliability acronyms. We thought others in the Reliability community may also wonder what the differences are between Failure... [ more ]
Guest A few years ago I had the same doubt.I asked Mr.Robert.J.Latino(www.reliability.com,PROACT Software)for an explanation.He send me a reply which I have copied below. Thomas Purackal. ---------------------------------------------- Recently, Reliability Center, Inc. received an inquiry from one of our web visitors asking the differences between three confusingly similar Reliability acronyms. We thought others in the Reliability community may also wonder what the differences are between Failure... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Conveyor Tail Pulley Bearing Damage
Registered Member Originally Posted by MarkSl: My customer recently removed an NTN 22220KC3 bearing from the tail pulley of a conveyor due to increasing floor noise in the FFT spectrum and impacting in the waveform. We have taken a grease sample from within the rolling elements, cleaned and dismantled the bearing. Wear is evident in the raceways and the rollers which is consistent with grease contamination from iron ore dust (site is a iron ore loading facility). Grease analysis showed 7669ppm of iron and it... [ more ]
Registered Member Egg shaped bearing housing/shaft and misalignment of the bearing can cause 180 degree roller issues [ more ]
Registered Member I would dig more in the installation and the way it was mounted, and how long has it been stationary while loaded. Why don't you use a shielded bearing to avoid any failure in case the seal failed? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Repetitive Bearing failure - Horizontal Motor mounted vertically
Registered Member Hello, maybe too late for this but i had a similiar problem with different equipment. new installation. we replaced the motor with a different manufacturer and that solved the problem. our buyers had the inexpensive motor route. [ more ]
Registered Member I doubt that this issue is just about the breaings only. It has to be looked into a wider scope. [ more ]
Registered Member Determining the nature of the failures is essential. Remove the next failed bearing and either send it off for analysis of cut it open and compare it to the free wall chart that SKF or FAG or just about any bearing manufacturer will give you. Collect and analyze vibration data to predict the failures while you determine the cause and corrective measures. Premature bearing failures are usually caused by improper loading due to design or installation defects or lubrication problems. The cause... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Abnormal sound and high vibration from Motor in solo run
Registered Member Furthermore, in your first case there are harmonics of 80 Hz that are probably related to VFD (750 rpm / 990 rpm is almost 0,8). In your second case there can be seen frequency at 4xrpm, which could be related to number of poles. Although there are probably 8 poles. [ more ]
Registered Member All indicators are saying the problem has some electric background related with VFD or motor electric elements. What I find strange in your data is practically no rpm frequency, just harmonics. I have never seen anything like this at such big motors. I would also check your vibration collector settings, cables, accelerometers etc... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Gas Turbine Tilted Pad Journal Bearing Failure
Registered Member Dear Pawannlng, the possibles causes are: 1.- misalignment (external misalignment) 2.- bearing housing excentricity (internal misalignment) 3.- low lub oil pressure in bearing or any restriction in lub line. 4.- over radial load. 5.- Preload in bearing (internal or external) we can rule out the last possibles causes using technologies that Rotating Guy said (Shaft centerline, sequence of orbit and time signal, bode and polar possible, spectrum, etc). [ more ]
Registered Member Dear Pawan, Without referring the diagnostic plots i think its very difficult to pin point the root causes of the failure. For fluid film tilting pad bearings, we need to refer more plots and one plot may not give clear conclusion. My opinion, since i am practicing vibration analyst more into this type of bearings. For hydro machines this type bearings are commonly used. Sherub [ more ]
Registered Member Dear Sir Oil analysis was done six month back and report was normal. I am attaching only available vibration plot. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
High Vibration on bearing #2 and #3 on gas Turbine frame 9E (100 MW)
Registered Member Hi We have same problem in GE frame 9 Load variation vib in BRG#2&3 vibration signature analysis is like misalignment 1X,2X,... also we have high vibration near 25 mm/s in BRG#1 at critical speed in running the unit and in BRG#3 in shutting down the unit. We suspect to misalignment of the bearing due to casing slippage Please help us that other reasons for this problem. Our thinking about source of vibration is right. thank you [ more ]
Registered Member First, I think you should give us some data (APHT trend, waterfall, SCL, orbit... if any)for review and also the arrangement of machine. I do not know where is bearing#2 or 3 and so on. You said that the casing have done bore alignment due to center of bearing housing 2 and 3 is not coincided. How about the alignment result and how about the rotor center position check (done at some hole on casing). how about labyrinth clearance at both side of bearing? how about the phase? [ more ]
Registered Member please to help me ??? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Worm gear alignment
Registered Member I've redone the attachment since some people had trouble with the previous. More on worm gear lubricants... One type of lubricant type commonly used with worm gears is mineral-based, industrial extreme pressure (EP) gear oils. This will give you problems with a brass or bronze worm gear at elavated temperatures. Your 180 deg that you state is normal is too high for this type of oil. There is also a group PAO gear lubricants that work well in worm gear applications but again, since these... [ more ]
Registered Member Danny, this is all i can post for the vib data. John, I couldn't open the file; we use a PAG synthetic oil for worm gear; oil level was ok. 680 was changed to 460 due to heat in other unit with mfg recommendation. This sat idle, 2yr, was flushed and then put in service, with a few days use to test, and this was found. No "known" issues prior to use. Leaker yes, and that may have been the main contributor. Hot bearing made us check it out for crud in oil channel possibly not getting oil to... [ more ]
Registered Member billw, some keys things needed in failure analysis of worms gears isn't clear from the pictures. However, based on what I see/read the history (as requested by Danny Harvey) might prove to be helpful. For one thing 245 deg F temperature would be very unusual unless there were some environmental considerations that might explain a temp that high (you say normal is 180). I would be looking for things that might cause high temperatures...480 oil, can you clarify exactly what oil is being used? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
compressor bearing failure
Registered Member Dear All, We are experiencing an increased temperature and a buzzing sound in two of our four ammonia compressors. From the vibration spectra gathered, we have identified peaks on the bearing faults frequencies and reported for a bearing replacement on the motor bearings. Hope you could give me your advise and opinion on this. Attached are the spectra. Regards, Philip [ more ]
Registered Member MARIO, I AM SORRY. I DO NOT AGREE WITH YOU. FROM YOUR POINT OF VIEW FACE TO FACE ARRANGEMENT IS MORE RIGID. RATHER, BACK TO BACK ARRANGEMENT IS MORE RIGID. can be confirmed from skf webste. WHAT IS THE CONTACT ANGLE OF THE BEARING? THERE MAY BE LESS PRELOAD THAN REQUIRED AS PER THE CONTACT ANGLE. WITH INCREASING ANGLE LOAD BEARING ABILITY INCREASES. LOCKNUT SHOULD BE TIGHTENED TO REDUCE CLEARANCE TO ZERO. IRSHAD [ more ]
Registered Member Dear I believe the bearings are mounted with the thickest part of inner ring in the middle, becomes more rigid mounting. When the shaft is measured from 70.001, 70.002 I think it has little grasp, given that 1 to 3 microns in diameter is insignificant to me that would be 15 to 25 microns. Checks if the oil return channel works, you can have oil injection but he did not leave and then carbonize. Regards Mário [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Firewater pumps p&id and network over pressure protection
Registered Member Not sure what you are looking at but my copy, NFPA 20 is titled Standard for the Installation of Stationary Pumps for Fire Protection . Further, chapter 4 has the following contents Chapter 4 General Requirements 4.1 Pumps. 4.2 Approval Required. 4.3 Pump Operation. 4.4 Fire Pump Unit Performance. 4.5 Certified Shop Test. 4.6 Liquid Supplies. 4.7 Pumps, Drivers, and Controllers. 4.8 Self-Regulating Variable Speed Fire Pump Units. 4.9 Multistage Multiport Pump. 4.10 Centrifugal Fire Pump... [ more ]
Registered Member Interesting, never noticed before because the title doesn't exactly scream "fire pumps". It also doesn't contain anything resembling a P&ID from a cursory scan, and simply references NFPA 70 (NEC) for electrical installation requirements. [ more ]
Registered Member What about NFPA 20? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
pipe strain measurement
Registered Member Hi AKHTAR, For some machines we didnot always get this pipe stain through shaft movement measurement . Example as I knew ,For integrally geared centrifugal compressor and steam turbine we did before we basically check this pipe strain through casing movement measurement. So I think maybe we should use a most sensitive method to do this. Thanks Lux [ more ]
Registered Member It is a word 2007 file and will not open with previous versions of microsoft word. Regards Irshad [ more ]
Registered Member Dear AKHTAR, Thanks for your help. Would you like to re-post your attachments again? the current attachment type cannot be opened . Thanks Lux [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Reciprocating Compressor Liner Failure
Registered Member Greetings Pawan, Good case study. 1. One thing is sure after overhaul and fitted the piston ring failed with in 2 days. 2. Especially when lowering the piston into liner, the guide ring, if having any scratches or dents or when forcing the piston into the cylinder liner normally the bottom ring can stuck or break and continue to run the broken piece can damage the piston and liner. This failure occurs in Tandem compounding pistons. In Marine Industry we have faced this type of failures for... [ more ]
Registered Member dear sir have you n checked the suction and discharge valves ? if you sure about maintenance of all components and installation procedures ,you should looking for cause around operation after overhauling .for example be sure about condensate gas or liquid drainage during operation. best regards [ more ]
Registered Member Was the cylinder starved of processed gas? How about the end devices that was to shut down the unit for excessive vibration are they properly installed and working? from your explanation though not too clear- Rod reversal due to lubrication issues might be the root cause. [ more ]
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Gas Turbine Bearing Failure - Lube Oil Leakage Caught Fire
Registered Member During inspection, the brass oil seal was found damaged. So, there is a possibility the oil could leak from Brg#4 and got fire, but question is why Bearing#4 which is near to fire location is not melted and how the fire traveled from Brg#4 towards Brg#3 ? You know its Turbine Section , the pressure at Brg#3 is higher than the pressure at Brg#4 [ more ]
Registered Member It is possible that the shaft is been hot due to fire and make the babbit overheat like picture. You should take event sequence and see what happen near the event time. Focus to oil system and clearance, i think you will get your answer. [ more ]
Registered Member The Ventilation Fan was also tripped due to breakage of its belt which may increase the T of enclosure and which further melt the Babbitt white metal which leads to bearing failure ?? I am not sure, can u recognize from bearing pic, is it melted during running or stationary? or is it melted due to high LO temp??? I am not sure [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cyclic vibration pattern analysis
Registered Member I would suggest checking more operating parameters in order to have a better chance to understand the possible problem. Sometimes, compressor upstream or downstream equipment are unstable and affect the compressor. Sometimes, compressor auxiliaries such as lube oil temperature control system is not tuned perfectly and can result in compressor instability. Spectrum comparison could help a little if you can post data for high and low times. I tend to agree with the comment given about the low... [ more ]
Registered Member Actually, In my experience, i have not met the morton effect yet. So, my thinking is just my sense. The speed could be not exactly in the case but i think that your case is not morton effect. Your phase change is not cyclic and i sure that your compressor is between bearing type which motorn effect is rarely occurred. My thinking could be total wrong! NVD [ more ]
Registered Member Dear NGO DINH Why do you think that my case is not morton effect due to speed of 3000rpm? Could you explain more detail with speed? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Motor Current of Dilution Air Blower is very high
Registered Member I would definitely do a holistic look at the entire system. I would suggest one of the points to check would be an infrared scan of the power wiring to the motor including contactor, and the connections at the terminal box. A high-resistance connection will give you high current with a constant horsepower load on the line and will cause excess heating as well. Best Regards, Michael Meehan, CMRP, CRL [ more ]
Registered Member Is the motor current the same (high) on all 3 phases? Is the motor on an across the line starter? Has any part of the system changed compared to when it was working properly? Are there any louvers on the ductwork system that have been neglected or changed? Louver adjustments are commonly an overlooked cause of problems. People tend to take the louver system for granted. The louvers controlling air flow in a fan and ductwork system is analogous to a throttle plate and choke plate in a... [ more ]
Registered Member How about the fan performance? Blockage on the suction side will starve the fan of air and reduce motor amps, air flow and static pressure Fixing the belts would also cause the fan to increase in speed, this in turn will cause amps to increase, more air flow and more static pressure http://www.solutionsforair.com...t/pdfs/fancurves.pdf The fan will have an operating curve, changing wheel size diameter or width, fan wheel style, fan rpm, ductwork length/diameter or air temperature, humidity,... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
WHPU LP Pump failures
Registered Member Hello RGF12, Thank you for the reply! Unfortunately we do not have any vibration data, there is no vibration routes for these pumps since the stand-by is started whenever the duty pump fails and it does not trip the plant/result in a production loss (not a priority for proactive maintenance). In addition, the pumps do not run 24/7, the pumps provide pressure to accumulators in the hydraulic system, hence, only operate when the accumulators are low, therefore, it is difficult to retrieve data... [ more ]
Registered Member Great presentation. Do you have any oil analysis data? These type of pumps are sensitive to oil condition and routine oil analysis with an emphasis on particle counts and wear metals may give you some early warning of pending failure. Do you have any vibration data? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
High turbo expander load bearing temperature
Registered Member Dung, Yours is different from mine. Mine is the turbo-expander which is unique in Vietnam. Sorry that I have no idea about your issue. Kind regards. Tu Thanh Pham [ more ]
Registered Member Hi Tu ! i have the same problem with our Bearing @ 3000 rpm detail spherical double ring bearing . I follow the specs from supplier with radial clearance . but when motor start to full load , the temp rise up and after 30mins the temp steady at 63 degC ( alarm at 75 deg and stop at 80deg) . it look unusual . I do not know the reason why and check with vibration tool they have acceleration (gE ) it is exceptable . What i think is the seal , you crosscheck it again ? [ more ]
Registered Member Dear Turb1, Thank you for your response. This issue still exists now. The load bearing temperature is still high, reaching the alarm limit when the speed is over 25600 RPM. I also think the bearing clearance is the root cause, but because of the plant process, I have to wait until September 01st for shutdown the machine and re-inspect it. Thank you and kind regards. Tu Thanh Pham [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cavitation?
Registered Member Could you please attach the vibration spectrum and acceleration envelop spectrum and all overall vibration in radial direction and axial at pump side and motor or turbine. Mention please the type of equipment its overhang or between bearing. If you have been pulled out the pump for bearing replacement and sudden the vibrations shoot up could be the main reason is misalignment or coupling bolts not properly tighten or pump front leg support plate bolt is not properly tighten. [ more ]
Registered Member JJ A I dont think anyone should get offended as you are correct. I have been whipped similarly before using the Vibe will find it technique. Similar situation except upstream a gate valve was partially closed just enough to restrict pump at operation speed. this showed high freq. and acted like bearings. replacement diddnt do much better adding vacume gage showed it climbed well then started cavitation right where drive dropped out of hi amps start mode. We failed to see the probblem by... [ more ]
Registered Member Not to rain on anyone's parade but analyzing vibration data isn't anywhere near as high a priority as checking the pump operating data to determine if there is a NPSH issue. To that end, what is the fluid? What are the inlet and discharge pressures and temperatures? and; What type of pump are we dealing with? Do you have the pump curve? If so then you need to check the net positive suction head available and compare that with net positive suction head required (which should be shown on the... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Shaft axial displacement
Registered Member What is your observation for the failure? What was the exact scenerio.Could u plz explain? [ more ]
Registered Member What kind of turbine; hp, lp, double flow, condensing, non-condensing? What's it driving; gearbox, compressor, generator, etc. How is it coupled; flange to flange, gear type coupling, rtc. [ more ]
Registered Member Thrust forces equation has been precomputed already during design for varying load conditions and this is where design of thrust bearing will start (it is unlikely that design had miscalculation). SO if it's not something that change with the thrust bearing (unlikely that design has miscalculation) and operating condition are you said normal then it has to do with other else. How about your vibration, any chance you have higher misalignment, how about your balancing force within the balance... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Belt driven motors
Registered Member Thanks for all the replies. [ more ]
Registered Member In general the answer is "yes", belt driven motors should have cylindrical rolling element bearings on the drive end (DE). Ball bearings will work and are often found in belt and chain drive applications, but will experience reduced life when compared to direct coupled applications. Please make sure to uniquely identify motors with cylindrical rolling element bearings as these bearings are not well suited for direct coupled application. If used in a direct coupled drive arrangement the... [ more ]
Registered Member I have seen several smaller (less than 10 HP?) motors with deep groove ball brngs on the drive end. I don't think there is any problem with them if the design, as Danny says, is correct. D [ more ]
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Fan Vibration
Registered Member Most probably the reason resonant, balancing is not solve problem and we try very much [ more ]
Registered Member 6/. Measure vibration in 3 directions at all 4 Bearings. Shut fan off, lock out, Mark coupling with paint marker, unbolt coupling and rotate 90 degrees. (We usually start with keyways 180 degree apart, or locate original match marks if they exist) Get the vibration as low as you can using the coupling and than balance the fan wheel as low as you can time permitting. 7/ Record final set of readings and begin New Trend. Let us know the outcome Thank You [ more ]
Registered Member 4/ Based on your Spectrums, I would replace the Fan Bearings again. Continue to "Trend" the Fan Bearings until you reach an optimum time to schedule replacement. Be certain to pay particular attention to the Outside diameter of the bearing and the inside diameter of the Bearing Housing. If the Bearing is loose in the housing, the movement can produce similar Spectrums. (3X appears more often 2X, but I've seen similar Spectrums on Monoblocks (fan bearing housing) 5/ Check fan bearing Housing... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Fin Fan Motor bearing problem
Registered Member fianda100185, Some electric motors are manufactured to be mounted horizontally, on most fin fans they are mounted vertically. You will need to check with the builder to make sure the motors have the proper thrust bearings for your application. [ more ]
Registered Member Assuming that your fin fans are belt driven as everyone that I've encountered is... What type of bearing failure is being experienced? Ie., inner, outter, ball, cage? Which bearings are failing; outboard, inboard or both? Is it possible that the belts are being over tightened upon installation? Is it the same tradesperson changing belts? Is the machine alignment between sheaves, etc correct? [ more ]
Registered Member what is a fin fan motor? what is the application? In what way are the bearings failing, is it always rhe same failure mode? what type of bearing? Always the drive or non drive end bearing? do you have any photos of the failed bearings? any other details, motor rpm etc [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
help about problem when downloading from 3500 system configuration to 3500 rack
Registered Member Thanks everybody. I've fixed this problem. It because 3500 configuration software only support config one 3500/92 module per time. I've uploaded program from rack then remove one com92 module from 3500 software(vitual) after that i've configured for new 3500/42M module and download it to rack. Everything is ok! [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Motor Shaft Broken...
Registered Member Thanks John.. Thatz a good information.. [ more ]
Registered Member Go to http://www.mt-online.com/july2...is-of-machine-shafts for an excellent treatise on both ductile and brittle failure modes. Take note however of the statement near the top that reads "When shafts DO break, however, there are almost always as many theories regarding the suspected culprits as there are people involved." [ more ]
Registered Member Does it look like it was in the keyway too? D [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Delayed Coker Unit Heater Charge Pump Failure
Registered Member Hi Sreejith, can the intake to the pump become restricted? if there was an unusually high vacuum on the intake that may cause a gas bubbles to form and the resulting bubble implosion could cause the damage but I would expected that to be on the vacuum side of the pump vane, high pressure damage logically suggests the type of damage would be an abrasion erosion damage but I'm not that experienced with cavitation damage, if there is a hard particle in the system a wear debris analysis on the... [ more ]
Registered Member @Vibmaster: There is a possibility of hard catalyst particles entering in the pump. That is what the OEM suspects the root cause. [ more ]
Registered Member Any chance of ingress of foreign material inside the pump causing erosion of the components. Vibmaster [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
GE gas turbine 88QV oil mist eliminator showering oil more
Registered Member never work with GE gas turbine. if it is oil console oil vent you are referring, since you are from uae, you might want to consider additional heat from ambient in your investigation [ more ]
Registered Member My Powerplant use Gas Turbine Model 9E. Let's review before the Discharge of oil from oil-Line of why some 1. Filter is dead or not. (But most will find that more than a ton). 2. Vacuum Pump to suck wind. 3. Caused by the gradual deterioration of Filter, then adjust based on changing Filter Damper Damper forget to adjust it back. 4. Media's Filter is not valid according to Spec. Is the compression of the Media too little water than normal, thus causing the fluid to the outside. Adisorn [ more ]
Registered Member check performance of oil mist fan and fan suction valve position. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Geared compressor bull gear DE angular contact bearing failure
Registered Member Hello Sir, Good to see your response. Yes, it is very strange to current bearing failure status. In addition, during the investigation, we also found this compressor got surge many times in the past becasue this machine was always running at turndown mode due to low demand from customer.----this should actually contributed to this bearing failure. Thanks, LUX [ more ]
Registered Member Dear Lux, Very interesting case of failure of bearing, analyzing of evidences: 1.- Only one ball was damaged. 2.- The location of failure in inner face of thrust bearing. possible causes, 1.- Not enough axial play during bearing Installation, that's mean the bearing was preloaded axially. 2.- Bad quality of bearing, it is possible to find fakes bearing in market. 3.- Excessive axial load due to coupling pre-stretch. Lack of thrust bearing temperature reading, was a factor that early action... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Reference for root cause analysis
Registered Member Thanks dear john for useful information [ more ]
Registered Member Conceptually, RCA is a wide field, but I assume you mean with respect to machinery. One starting point might be https://conference.reliablepla...root-cause-analysis/ . I would also suggest you look around that Conference operator for related info. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Motor triping issue
Registered Member Thank you for the update. [ more ]
Registered Member Finally we found the problem for Motor Tripping issue ...... Rated AMPS = 88 Before tripping rely was 80 AMPS after that rely set 80 to 88 AMPS. Now equipment healthy condition and running smoothly . [ more ]
Registered Member Bijoy, Try to replace the thermal overload relay. regards, [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Is Bearing having fluting marks?
Registered Member First time on this blog and I see these postings are a couple years old, but here goes it anyway: I reviewed the pictures and agree you are experiencing electrically induced bearing failure. Incidence rates of bearing failure on VFD motors is at least 60% by 2 years and only continues to climb from there. It is a well-accepted and pervasive problem that particularly plagues operations that run 24/7. The following information is based on long-term field and lab studies over 30 years. 1)... [ more ]
Registered Member Yes, that's textbook fluting. There have been many good discussions here about it over the years: https://www.maintenance.org/top...63202347#77420702863 [ more ]
Registered Member innner race of NU230 Brg. in zoom view. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Generator Shaft wear where the bearing sits.
Registered Member Thank you very much for the help gentlemen (Mark and Dinh) i will check my grounding [ more ]
Registered Member Please check your ground system especially shaft ground and casing ground. In normally, for motor, we usually see insulation bearing at NDE side. But your case, it is not. I think Mark have the same case. YOu should learn from him for solution. [ more ]
Registered Member Hi mark thank you, the wear you had on the shaft of your motor is very alike as the one I have in my generator, so I guess you are correct this electrical erosion is caused by shaft currents, no issues in the motor driven by the generator, but yes the generator is on VFD. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Helical Gearbox failure and sub-synchronous axial vibrations
Registered Member NOT the expert on this subject, what I see in data provided is axial thrusting on the double helical gear teeth. This can be caused by unlevel gearbox and worn gear tooth profile to name a couple. The gear tooth broke toward the outer edge of the gear which too can indicate axial thrusting. Sub synchronous, do you mean vibration is below motor or compressor shaft speeds? Are the failed gear teeth next to each other or just a couple of teeth apart? Can you share more data, gearbox... [ more ]
Registered Member John in PA would be your best resource on this board in this matter. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Bearing temperature swings
Registered Member I have heard presentations by UE Systems. Check their website. Ken On Jan 18, 2016 7:38 PM, AMP - Asset Management Professionals < forum@maintenance.org > wrote: > > == To reply by email, write above this line. == > Hello, lubeguy: > We're sending you this notification because you are either following the forum, the content, or the author listed below. > New Reply To Topic > Subject: Bearing temperature swings > Reply By: Missisquoi > In: Reliability Engineering... [ more ]
Registered Member I like SDT's line of products. They have different models to fit any program. Simple meter with a digital readout and a magnetically held transducer is all you need. Procedures are very simple...less than 30 minutes of training until you are making a positive impact on your program. Same meter can also be used for air leaks and steam traps! Great little piece of equipment. [ more ]
Registered Member I have read about ultrasonic devices for guiding greasing. Any recommendations on which ultrasonic device to use or the best place to get one? Thanks! [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Generator overcurrent trip
Registered Member If no doubt about the generator, you should check the electrical transformers on the line just after. You should also check that the AVR is working without any problem (observing the trending photos, even before the problem electrical parameters are not stable) . To get more precise and significant data, an oscilloperturbograph report is better for instant recording of generator outlet electrical current, voltage and frequency, and excitation voltage and current measurements. Good luck. [ more ]
Registered Member After 4 hours of running, does this mean this is the first time the unit has generated power since rewinding? Was there a problem before and that is why the generator was rewound? Have you performed and infrared scan of ALL electrical components while in operation? Even though rewinding has been done, I would not think the problem would jump from phase to phase. If you are feeding parallel to a grid, is the grid also seeing this same amp swing or it is just your system? [ more ]
Registered Member Dear colleagues, Sorry for my late response, I have just collected some information. The generator is feeding a network as parallel to grid. Current increasing occurs on individual phases An AVR is used to manage excitation and stator voltage The generator is driven by a MAN engine. The customer checked all related issues about engine side and additionally generator (rotor, stator, excitation windings,diodes,..) No abnormal findings. Meanwhile both rotor and stator have been rewound by a... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Electrical or mechanical Vibrations
Registered Member Thanks Electricpete,thats the infomation i was looking for. [ more ]
Registered Member I'll assume you're talking about an electric motor and distinguishing vibration from pure mechanical causes (unbalnce, misalignment for example) with vibration from electromagnetic causes (magnetic force). I agree with rgf.... it's a broad question, and I guarantee my answer will not cover all the angles. Here's what is typically taught in training: 2*LF frequency means electrical causes. Most commonly associated with: static eccentricity of airgap, motor foot conditions (especially 2-pole... [ more ]
Registered Member Any chance you really mean electrical and mechanical "runout"? John from PA [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Ejector shutdown in Steam turbine
Registered Member jawal, it is very subjective. few things; 1. steam seal is having signifant leak if you can feel the steam is blowing from any of the end seals. if you confirmed that your ejector is working fine, then yes, your seal clearance is already off. if ejector is not working, your seal may ok that you verify that after correcting the ejector. for good seal + good ejector, normally you will find the the loose fabric get sucked. i nromally used loose fabric tied to a long stick and direct the fabric... [ more ]
Registered Member good you opened this case since. Well, the shaft is equipped with deflector disc on both ends. yes there is was significant amout of leaks steam then it went away after we lined up ejector again. two things worth ask about: 1- is there a standard for minimum diameter for delector disc? 2- lately we started to find too much water migrated inside lube oil. I was thinking if the steam seal is stated to leak, is there a way i can verify if clearanc is too high without opening unit. our unit has... [ more ]
Registered Member the only impact i can see is steam leaking out from the end seal. should your turbine shaft is not equipped with a deflector disc between end seal and bearing seal, the subsequent impact would be direct jetlike steam hitting the bearing seal and result in moisture ingression into oil system. if you have deflector disc, then it will be significantly minimized, hence, depending upon the amount of leak steam (depends on your current seal clearance) you can run without the gland ejector for a... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cooling tower fan motor current variation
Registered Member Is a 10 amp swing really a problem with this unit? [ more ]
Registered Member Sometime problem rotor cage can be seen and measured only with load , increasing temperature and growth cracks and poor joint between rotor cage and conductor . Motor offload running with nearly synchronous speed it may not be sufficient to confirm a problem with the rotor in some cases . Good luck [ more ]
Registered Member There is no abnormal sound so far yet. As far as the fan stallation is concerned how could that be analyzed? Our electrical section is neglecting the rotor problem they are saying if problem is due to motor then it must be reflected on motor offload condition which we tested and found normal. [ more ]
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A screw compressor was seized
Registered Member Dinh! You’re right! So we are waiting the analysis result. For further information i will post what i have. You known without knowledge of the machine this is likely too much of a guessing game. Regards Vastocean. [ more ]
Registered Member The bearing is rolling element bearing, isn't it? If so, the clearance is very tight. It is not exactly the rule but normally, clearance of compressor must bigger bearing clearance. [ more ]
Registered Member Dear Dinh! We sent them for analyzing but not yet receive a result. Regarding the bearing clearance we checked yet. But we do not have compressor’s clearance, so that no way to compare. Regards Vastocean. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
what is feature about "False Brinelling" ,why the bearing failed
Registered Member Only select equipment. The practice was initiated after root-cause analysis indicated false brinelling. This lead to vibration analysis of the standby pump, showing that it indeed was being excessively vibrated by the pump next to it. I know that we then used vibration analysis to check the standby pumps that were critical service or had a history of similar failure to find other examples of high standby vibration. I think that is the right approach. The rotation, especially in a nuclear... [ more ]
Registered Member Rich, do you rotate all rotating equipment in standby mode or only for selecte equipment? [ more ]
Registered Member In addition to the advice about grease, periodic rotation of the stationary shaft will minimize the effects of the false brinnelling. We used to do this with a weekly operator task to rotate the shaft of a standby high pressure pump that had experienced false brinnelling failures, and we had confirmed high vibration levels during shutdown, due to the adjacent pump. Since yours is a crushing application, you are probably talking about high levels from the adjacent machine. In some cases,... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Tube bundle failure
Registered Member My observatio is 1.looks like that the temperature had gone high due(tube side). 2.Thinning of tube due to corrossion at elevated temperaure. 3. Something like Gas formation on shell side(may be nascent hydrogen release) the bucking is inside in all the cases as could be seen in the picture. 4. Has any alalysis been carried on steam quality,Where is the steam inlet in relation to the damage area shown in picture? [ more ]
Registered Member May be bi-metallic corrosion has caused the failure of the joint between tube and tube-sheet which resulted in buckling of the tube inwards due to weight of water flowing through it and its. velocity [ more ]
Registered Member Is it known for sure that the indentations did not exist when the tube bundle was new? I vote along with those who say it must have seen a large differential pressure (lower within the tubes). But I'm not a mechanical guy. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
GEAR FAILURE AT SCREW PUMP
Registered Member Thanks Dave for material. the lubrication is just follow the manufacturer and no any abnormal. The spec for oil is VG100, The oil was maintaining and changing as manufacturer then i have no doubt in oil issue. As see the defect mark, look like a very excessive load effect on gear and broken the teeth surface, the spectrum also shows high GMF relate to gear wear , also indicates very high load. then the next question is why the high load on the gear , i keep going my investigation on this... [ more ]
Registered Member https://www.machinerylubricati...ad/150/gear-failures https://www.rexnord.com/conten...ments/108-010_manual Here are a couple of links showing different failure modes Your images show the gear was loose on the shaft, lubrication is in question, gear material may not have been hardened to proper levels Dave [ more ]
Registered Member Dear DOMINICH.VO , increased noise floor with gear impact indication , are you maintaining and changing its lubrication as per the manufacturer recommendations and grade . Do you mean viscosity of pumping fluid , low viscosity might have some effect but i don't think so it is the main cause .For better understanding on this you can refer the manual and contact the support service . [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Mechanical seal failure
Registered Member Which fluid and which o-ring material. I think here is the answer. [ more ]
Registered Member Thanks Dave for some throwing some light [ more ]
Registered Member https://www.marcorubber.com/o-ring-failure.htm https://www.prepol.com/solutio...o-ring-failure-modes http://www.dichtomatik.mx/cata...alisis-de-fallas.pdf http://www.pspglobal.com/seal-failure.html http://www.madgetech.com/pdf_f...app_notes/orings.pdf Could be the type of barrier fluid you are using that is causing the oring to fail, could be the fluid you are pumping is attacking the oring, could be too hot for oring abilities. The above links have some good images and details of what to... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Submersible pumps burn out every week
Registered Member Thanks Dave, very helpfull. I will now gather data based on your suggestions, then analyze afterwards. [ more ]
Registered Member As others stated, need more details. Burn out, you mean the motor windings fail? Is there any temperature alarms for winding, moisture alarm for seal? Who is the OEM, the model, all will help in the diagnosis of your problem. IF the system has ran fine for years and you are now having issues. KISS principle, keep it simple stupid is a good practice, pardon the analogy, have you checked the discharge check valve for proper operation? Just because you see movement on the outside of the check... [ more ]
Registered Member Yes, it has enough power. It is the original design. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Problems in Gear Couplings, and their Remedies
Registered Member Well again, if you have some specific problems, post some pictures. I would suggest you visit http://www.rexnord.com/Content...ll-Types-Failure-Ana or http://www.tribology.co.uk/wp-...o-Gear-Couplings.pdf and download the content. One of the likely key issues with a gear type coupling at 13000 RPM will be sludge collecting in the teeth which can in time partially or totally lock up the coupling; see the attached diagram showing lubricant path through the teeth. This causes forces to be... [ more ]
Registered Member RPM: ~13k; Oil Lubrication [ more ]
Registered Member Share some photos of the failed coupling to start with. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Vacuum Pump grid coupling failure
Registered Member I wouldn't make any assumptions about alignment not being a problem without having checked it first. Overload is also a possible factor in a machine train like this where all shafts are the same size and in general designed for driving one machine. The middle machine coupling has to carry it's own load and the load of the machine after it. The first coupling (at the motor) carries the greatest load, I'd inspect it as well. [ more ]
Registered Member Alvin, 2 cents, the coupling hub teeth appear to be severely worn, the wear allows the grid to put pressure at the corners of the teeth instead of even pressure distribution across the tooth face. The teeth to the left of the three that are missing appear to have a very wide gap between the teeth? The teeth that are missing, the break appears to be old, suspect they have been cracked for awhile Do you have pics of the grid? It too holds valuable visual evidence Dave [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
U tube Heat Exchanger Failure in Tri Ethylene Glycol Service
Registered Member ITT Standard has an engineering staff to assist you in your questions. You will need to have all the data on you application for sizing a proper exchanger. Engineering a solution for your application will not be for free Dave [ more ]
Registered Member Thanks Dave for your input. Do you have any suggestions for material selection in this regard or reference to any technical literature so that we may look for the solution to this problem. [ more ]
Registered Member Wrong material of construction, too thin of tube wall thickness, blockage causing pressure to build just to name a few. You are dealing with a very tough service, high temp and high pressure. Was recently involved with a similar application and the cost to build a new exchanger was around 80,000 USD. Special materials of construction and precise engineering numbers are important to this application. Sounds more and more like the exchanger is not suited for the service you are operating it... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
High Vibration in Vertical direction and resonance
Registered Member Vertical vibration data are missing. Non synchronous single peaks are generally external to system.I think it is a VFD? Try changing your pump RPM.Since your bump test shows 1.6X as natural frequency, try to can find visible base frame flexibility too. Any soft foot checking? Compare with other similar pumps. Regards Irshad [ more ]
Registered Member Dear Akhtar pl find the spectrum attached . Pl note visibaly line stress doesnt seem thr in the system. [ more ]
Registered Member thanks akhtar ..will revert back with answers [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Criteria of Preventive maintenance
Registered Member Vinay, Yes, that is the correct approach. Note that the MTBF you want is for the failure mode "Fail to start and take full load". Based on generic data sources and a 2% unavailability, we get to the 4-8 weeks interval I mentioned earlier. The formula is good enough but there is a somewhat more accurate one also available. [ more ]
Registered Member Gentlemen, Can we use the 'Failure Finding Interval' concept of RCM here. In this case the interval to diagnose the Standby Saltwater Pump should be equal = 2 X Unavailability of DUTY Pump X MTBF of DUTY Pump Its like if Unavail = 1 %, MTBF = 1 Year Then Interval should be = 2 X 1% of 1 Year = One month. So the pump needs to be inspected with the desginated checklist once a month. AM i right folks ? ? -Vinay [ more ]
Registered Member Shahid, from your description of the pump, I suspect that you do not change oil (so we can skip oil analysis ) What happened? Rotor came off the shaft? Guide bushings/bearings worn? Suction screen plugged? Corrosion? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Taper roller bearing cage defect
Registered Member Mike, Your approach can work well too,but personally I have found I get more information out of the blokes if I show them that I'm there to make the job easier for them, I'm not there to point fingers and blame people. Lets find the root cause as quickly as possible and see what we can do to eliminate it. Hooch [ more ]
Registered Member In direct contradiction to what I said but I'd have to say some really good points Hooch. Thanks. Mike. [ more ]
Registered Member One thing to remember when thinking about this failure, WHAT DOES THE REST LOOK LIKE. I see it this way,the cone/cage is damaged (by a rotational style lock up)but the cup section of this bearing was not able to be recovered. Does this mean that there was excessive clearances as suggested? When looking at the rest of the bearing it does look to have excessive wear and a lack of lubrication (unless the rust marks occurred after the bearing was removed, which I very much doubt due to the... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
A separate posting board for RCFA
Registered Member If you do not get answers for the 5 whys... then you need to perform a RFCA analysis to find out the 5 because? [ more ]
Registered Member When you requested a new forum, I was going to ask: 1) why? 2) why? 3) why? 4) why? 5) why? My feeble attempt at maintenance humor (the 5 why's) Terry O [ more ]
Registered Member Not many questions asked. Thank you very much indeed, Terry!. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Shaft Failure of Turbo Type Air Compressor [PAP]
Registered Member Do the key and its groove have sharp angles or radius? [ more ]
Registered Member Hi Seo, Based from our failure analysis, we have ruled out the possibilities to two causes: 1) unbalance and 2) SCC; with unbalance as the more likely of the two. Similar to your case, we are now considering the upgrade of the impeller attachment to shrink fit (stud attachment is completely eliminated in this method). May I ask specifically what you mean by disturbance due to dust influx? In our case, we found dust/coal accumulation in the impeller shroud and blades which may have caused... [ more ]
Registered Member Dear Jeff We're still experiencing shaft failure repeatedly, so now I'm about to improve rotor design including fit type. Cuase our team conclude current design is too weak against disturbance like dust influx. Your case SCC seems really interesting to me. Could you let me know where SCC is found or initiated? If you don't mind me asking, can I see your upgarde method which you mentioned above? Regards. Seo [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
pillow bearings running hot
Registered Member It's better to determine the Root cause. What temperatures are you seeing, has the machine always had excessive temperatures or has this only recently started to occur. What is the brand, size and sealing arrangement of the Pillow Block. I have seen contact sealing arrangements in integrated pillow blocks such as the Dodge grip tight used in high speed applications (such as fans) cause high temperatures [ more ]
Registered Member Blow it on the shaft instead. Blowing it on the bearing cools the bearing housing and shrinks it on the hot insert. Cool the shaft and allow it to cool the bearing from the inside. Better yet, find out why the bearing is hot and fix it. This is an extremely expensive way to cool it. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Compressor abnormal sound
Registered Member Dear Pawanlng, I have gone through the various communications you have had. I wish to only know is whether the vent line on the clearance pocket outer head is open once the clearance pocket outer head unloads from 25% to No Load condition. If this is blanked due to some reason, then the chattering may occur in clearance pocket outer head. The OEM(Original Equipment Manufacturer) generally mention this in the compressor maintenance manual. Another aspect is to be checked is whether Road... [ more ]
Registered Member Hi pawan, It's really intresting. Could you give the following information. During startup you mentioned that the compressor is running smoothly at 0% load. Pls note down all the parameters including the motor amps and compare with that readings while you decrease the load from 25% to 0%. Which parameter is varying. Something is going wrong while you decrease the load from 25% to 0% Check from operation point of view. We faced one similar problem in one centrifugal compressor but there the... [ more ]
Registered Member no sir temperature is normal. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Motor Insulation Resistance
Registered Member Thank for your information.The motor is ok its just that the overload setting was wrongly set such that when you start the motor in delta it was tripping because it was drawing more current than the overload setting. [ more ]
Registered Member IR drop when you perform delta connection shoud occur because you have each of three phase insulations in paralel connection and also the leakage throug the motor TB. It is not a earth fault problem, it seem to be an overcurrent. You should measure the amps during the start. Does it reach rated speed? [ more ]
Registered Member A "Y" connected motor resistance is in series where the resistance adds together, delta is a parallel connection, see this link. http://www.firstelectricmotor.com/images/motcon17.jpg Not sure if you have any motor experience but a motor your size should have a LOW resistance between phases, typically I would anticipate using a Wheat Stone Bridge to measure motor resistance. Values should read like 1.04984 ohms, not Mohms. REVAN is correct, 30Mohm to ground is not a concern. You typically use... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
rolling bearing failure analysis documents
Registered Member Here is another one. I guess it´s for trucks but it looks the same inside. http://www.generalbearing.com/...iles/Hyatt%20BFA.pdf Olov [ more ]
Registered Member Electricpete After downloading all the posted links from your post i felt that i have to thank you for these invaluable documents. Thank you so much. Best regards Yousef [ more ]
Registered Member Pete, would you be able to share your Kingsbury material once again? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Fan Vibration spectrum analysis
Registered Member I think you are dealing with critical mechanical looseness, probably coming from the fan DE bearing (bearing housing / coupling / attachment as alternatives). Your spectra should have better resolution for detail analysis with some peak markers. Besides, imbalance could also be well increased, although it is hard to say in such bearing condition. I wouldn't operate much longer [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Bearing Failure
Registered Member Good catch with the feeler gage issue. The bearing being improperly set up with insufficient clearance creates the hoop stresses needed to crack the outer race in the way that you showed here. Rich Wurzbach MRG Labs [ more ]
Registered Member That's a really good point rich, to be honest I hadn't even thought about it, I should have really collected some of the old grease for that purpose. I'll remember that for next time. Yes so the grease line has been installed due to the access restrictions, it looks like it's achievable to just grease normally but it's actually about 7 feet off the platform, making it hard to reach. The grease line was checked after to make sure there wasn't any blockages. But I understand you're point , if... [ more ]
Registered Member There is another piece of information that can be added to help make the true root-cause determination more likely, and that is the analysis of the oil/grease and debris found in the failed bearing. While an outer race can crack due to significant weakening after a substantial amount of material has been removed, that is not the case here. It is more likely that a significant piece of the broken cage got trapped between the roller and outer race and caused deformation to induce the crack. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Two Speed Induction Motors
Registered Member https://www.allaboutcircuits.c...or-induction-motors/ http://i-gard.com/site/assets/...und_rotor_motors.pdf https://easa.com/resources/res...und-rotor-windings-1 Now what you describe is a wound rotor motor design If you take the resistors/speed control out of the picture you can narrow down the problem. Put a short lead on the three slip rings and tie all three leads together. This essentially is causing the motor to operate at high speed with no resistors in the circuit. If the motor... [ more ]
Registered Member Thanks for taking the time to reply. I forgot to mention this is a 3 phase unit, low speed is 1440 and high speed is 2900RPM. The motor has 6 wires emanating from the frame with 3 field resistances at approximately 25 ohms and the other 3 at approximately 16 ohms. It uses a rotary switch with a number of bridges or links to energize the appropriate winding. Also, here's a good article on 2-speed motors. https://precisionautomation.ne...on-two-speed-motors/ [ more ]
Registered Member Assume 3 phase motor, what you describe is a single phase condition or shorted winding. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Dry Gas Seal Failures
Registered Member How about materials of construction and pH of product, is the piping associated with the failing seal made of different material? Dave [ more ]
Registered Member Dear Ahmed contamination is from the gas process inside de compressor which brings with it particules of iron same problem for our case that happened last year , but with oil which came from another equipement and flood the compressor slowly . [ more ]
Registered Member Dear SAAD AHMED ! I don't know why iron can enter dry gas seal, because pressure of filtered gas always higher process gas at compressor. At our plant we have same problem with DGS, however root cause to failure DGS is liquid enter DGS to damage seal face. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cracks in impeller of three stage integrally geared centrifugal Air compressor
Registered Member I highly recommend the use of HEPA Filtration system, to avoid impeller erosion and incustration. Freudenberg EMaxx E10 or equivalent could be a good option [ more ]
Registered Member Dear Mr. Kanzariya, We too clean the impellers on a regular basis because we observe coke dust deposition on the impellers and it causes some unbalance in the rotors and cleaning does improve the vibration. We observed some erosion (not corrosion) on the impeller vanes. This could be due to moisture or coke dust on these high speed machines. And in one case pitting at the impeller backside where it sits on the tie rod. Don't just eliminate FOD. I have seen many cases where the foreign object... [ more ]
Registered Member Dear Yasaswy Thanks for sharing information. Bent...I think the bent one vane due to previous broken piece got chocked between diffuser and impeller that could damage the consecutive vanes....If it could be FOD that there might be any hitting marks in impeller eye but there is nothing in eye...Another way my point to share is that when there is long time deposits and fouling on impeller vanes that creats pitting on impellers ...same has been experienced in same make other compressor of same... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Bearing seizure and cage crack with out any high vibration
Registered Member Quote..."we inspect this bearing every fourth nightly but the vibration is in with in limits 2.1mm/sec and 0.5g before failure ." I see this was posted 6 months ago but I was wondering, since you said "we inspect this bearing every fourth nightly", can you post a few spectrums from this "inspect" ? My first impression is lack of lubrication, but seems like the data should have shown something, even lack of lubrication, during this inspection period. I am not sure what is meant by " every... [ more ]
Registered Member What's your said vibraiton point and direciton? How about axial vibraiton? it seems your bearing once bear high temperature from your photos [ more ]
Registered Member Actually here floating bearing is NDE , fixed bearing fan DE. if it is axial load damage it has to damage on inboard race way but inner ring two race ways are damaged [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Gas turbine - Compressor blade damage
Registered Member In this case, we test micro structure of blade we found some micro crack on blades tip start point of fracture and found vibration phase change after HGPI. and talk with OEM.>> rubbing is cause of fracture. But, a cause of rubbing, we're finding together with OEM. In normal case of rubbing is show in compressor blade clearance and rotor position but in this case compressor blade clearance and rotor position is not problem, it's on criteria. OEM find RCA around 3 month. Now we don't know. [ more ]
Registered Member What caused the rubbing? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Low Steam Turbine Performance
Registered Member Go to http://turbolab.tamu.edu/proc/...oproc/T42/index.html and then scroll down to the Case Studies section, specifically CST13: Successful online and offline cleaning of steam turbines without disassembly by Bladimir Gomez (PDVSA CRP Refinery) and Barry Snider (Small Hammer Incorporated). There is also content at http://turbolab.tamu.edu/proc/...proc/T33/index.html; scroll down to the Lectures section, specifically page 57 and the title NEW TECHNIQUE FOR ONLINE WASHING OF LARGE... [ more ]
Registered Member When is the last time the steam turbine is overhauled? Is water treatment and cooling water treatment proper as per specifications? Have you checked the troubleshooting guide by the OEM? [ more ]
Registered Member Carry out a borescope inspection [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
RCA Team
Registered Member Mr. Sohail In our site each area are responsible for your RCA. The security department uses the 5-Why and department maintenance / reliability analysis using a spreadsheet based on Reliability Centered Maintenance. All depends on how your system is organized. [ more ]
Registered Member Josh, The titles I quoted are mainly software solutions with different flavors. RCA is NOT software. I like to see it as 'thought-ware'. One can follow the RCA process without any software , but using them can help us with the process. I conduct RCA training courses (next one in KL in Nov. through petroEdge Singapore) w/o the use of software, so people know the process first. I do mention the various packages they could use to speed up and to organise rheir work. In a public forum, I do not... [ more ]
Registered Member Vee, I learnt about Kepneo-Trego but only heard of other RC methods. If you are familiar with all of them, could you comment on each suitability for what kind of failure scenarios for sharing purposes? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
gearbox shaft broken
Registered Member David, i do not think so no ,only measure vib usually there is a flexible coupling to reduce misalignment.however,in"HS3"picture,i cannot see the elastomeric flexible coupling only the coulping locked on the input shaft of gearbox. may be the elastomeric flexible couping lock on the motor output shaft. in this case,i have to check the gearbox input shaft diameter,does it larger than motor shaft.if the motor shaft is larger.i should incrise the gearbox shaft diameter or intall a elastomeric... [ more ]
Registered Member Leisure, Are there ( such as in the the keyway, coupling ) any physical signs of torcional vibration? Can you measure motor current in order to detect variable torque. Also shaft misalignment will also contribute to shaft bending fatique in particular if coupling is locked. [ more ]
Registered Member sorry add again [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Bearing failure
Registered Member You may have something wrong with the bearing housing, like a bump or something taking clearance out of the bearing if it's doing it again. [ more ]
Registered Member Rennie, Just edit your message and delete. Strange thing. I posted a reply with a file attached and mine was the only posting I could see. Maybe something is wrong with this part of the board. Hmmm. The attachment posted this time. Strange. [ more ]
Registered Member Rennie Did you witness/quality control the replacement of the latest bearing that failed? cracked inner ring????? was the shaft greased to assist fitting because of heavy interference? was the bearing heated prior to fitting? if so what method was used? or was the inner ring bashed on with a hammer. Was the work carried out in a clean enviroment? Just some thoughts Jonesy. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Dry gas seal leak
Registered Member You should check your buffer gas(nitrogen) supply.I gues that I would be because of high pessure or high flow of buffer gas.Just lower the pressure of buffer gas [ more ]
Registered Member Which standard is it? [ more ]
Registered Member Yes,we checked with the dry gas seal standard. But this case has the commercial reason. We want some explanation or comment for dicuss with OEM. [ more ]
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