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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
Accident at Russia’s Biggest Hydroelectric
Registered Member People, The 'official' account as well as the Power magazine report seems to focus on the fatigue cracks on the cover flange and bolting, This does not explain the upward forces lifting the 1500T assembly through the roof. The article in the International Water Power & Dam Construction, Dec. 22, 2010, offers a more plausible theory of a water hammer as the main source, see http://www.waterpowermagazine....sp?storyCode=2058518 If true, there is nothing to prevent the disaster happening... [ more ]
Registered Member Terrence , do you know what the latest news is around this disaster? What happened to those who where responsible?? [ more ]
Registered Member http://www.powermag.com/POWERnews/2216.html [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
RCA Facilitators
Registered Member Aubrey, Try PROACTonDemand by Reliability Center Inc., they will have facilitators and the software is quite impressive. See the link below for some details: http://www.youtube.com/watch?v=McYJJK6EcOo and good luck. [ more ]
Registered Member Thanks. I am trying to tie up a few loose ends here. Moved up here from Georgia and it is beautiful here. I am amazed how beautiful. Just got notice I am moving to Northwest Alabama. Here I go again... Aubrey [ more ]
Registered Member http://www.sachssalvaterra.com/ I had some experience with them when I lived in beautiful upstate NY....... [ 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
Arc welding?
Registered Member Of course the boilermakers say they always ground within 6" of the piece they are welding on. Everyone knows the fitter always ground on top of the safety ground next to the welding machine. :-) Aubrey [ more ]
Registered Member As i come from a fitter and turner background my number 1 rule is Whenever possible, blame the boilermakers. [ more ]
Registered Member Yes they look outward also back of race all brown like it got hot. New and old folks have welded on machine lately. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Aircond spitting water droplets
Registered Member Causes: High humidity AND the heat exchanger won't properly drain the condensate. [ more ]
Registered Member They suspect dirty coild which is to be cleaned using water spray and chemical. [ more ]
Registered Member Dirty air filter, low freon charge, dirty coil that has air blowing across it, door left open and over working the unit with too much humidity, dirty condensor that normally sits outside to name a few possibilities Hope this helps Dave [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Sychronous Motor Problem
Registered Member The motor runs but will not get up to speed...Is the exciter developing correct voltage under a load to no load condition? Have you performed any advanced testing like motor circuit testing with pdma or baker equipment on both the stator and rotor? Do you have all three phases of power to the stator with proper voltage? Have you inspected the breaker that supplies the voltage to the stator? Because the motor does starts that's a good thing, if the stator windings had issues they would mostly... [ 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
Oil wirl or flow related instability
Registered Member See the link below. contains a nice description of stalling and surging. http://www.scribd.com/doc/2357...ntrifugal-Compressor Vibmaster [ more ]
Registered Member thanks vibmaster . The driver was steam turbine I was not able to analyse the load absorbed by the compressor since flow related instability was not envisaged during data collection . The orbits where very unstable with no noticeable shapes for the shaft precession . There was flow fluctuation . But is there any particular range in the subsychronus region which is caused due to flow related vibration ?l [ more ]
Registered Member If it is surging, it will reflect in variation of pressure, motor current also. The subharmonics series of small amplitudes you see , may be due to surge induced turbulence. This is only a guess since you have not submitted any spectrum/ orbits. Vibmaster [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
RCA Software
Registered Member Inspector, Software enables you to execute a process that you already understand well. RCA is a logical thinking process, that does not necessarily need any software to execute. It works best as a team activity. If you are operating a Process Plant, the team will have operators, discipline engineers and supporting department members e.g. stores or logistics, guided by a facilitator. RCA is entirely evidence-driven. So it needs a certain level of discipline; data has to be secured and not... [ more ]
Registered Member Before recommending software, it would be nice to know more about what you plan to do with it. What type of problems are you investigating? How do you see the software helping you perform your job? Software implements a root cause system. The system that would work for you depends on what you plan to investigate. Perhaps you should be picking a root cause system and software? Best Regards, Mark Paradies President, System Improvements The TapRooT® Folks http://www.taproot.com [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
BALANCING MACHINE
Registered Member HP, Frame, TEFC totally enclosed fan cooled, rpm, voltage. The motor base will most likely need to be changed. Match the VSD with the motor parameters. 22 kw is 30HP http://www.aqua-calc.com/conve...lowatt-to-horsepower Assume it is a belt drive, will most likely need to change the bushing on the motor pulley due to different motor shaft sizes. Dave [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Diesel Generator Fuel conversion from oil to natural gas
Registered Member Yes agreed! Thanks [ more ]
Registered Member At Fukushima, cooling water could be injected into reactor core due to flooding of the equipment (Main DG sets and fire water diesel engines) and failure of pipelines of fire water due to sunami and high seismic activity. The equipment availability is not only an issue of fuel availability. Also, this forum can not suggest you regarding conversion of diesel engines to gas fired engines . I have already advised to contact your OEM /established players in the field . Only they can advise... [ more ]
Registered Member @Vibmaster Technical skill and emergency planning as well as execution, all will be depended upon availability of equipmenets in case of Fukushima like situations. So diversity and availability of critical mitigational equipments are essential. [ 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
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
FAILURE OF 11KV HV CABLE
Registered Member Revan, Mail me at adityakorde@yahoo.com; will send you details. In general; On-Line PD testing is very effective in detecting faults in terminations & joints in all cables (XLPE & PILC). PD within the actual XLPE material itself will lead to fast failures & can be missed by the on-line PD test (unless you test the cables very often). PILC is much more resistant to PD, so material degradation in PILC can be detected well in advance. End user feedback though is that joint &... [ more ]
Registered Member Thanks Aditya for your reply. Any party in India which undertake these On-line partial discharge testing services and how effective the results. Regards, Revan. [ more ]
Registered Member Revan, Tan delta & partial discharge testing (off-line) of cables is now being done by Reliance Industries for critical cables. On-line partial discharge testing too is now possible, with PD mapping options. Regards, Aditya [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Vibration Shooting Circulating Water Pump (Vertical)
Registered Member what is meant by random? It shoots to higher values and then comes down automatically or after shooting persists there. So, these are vertical condenser circulating water pumps. Reverse thrust acting on the pump during start up is frequently responsible for teflon bearings damage which increases shaft eccentricity causing bearing clearance to increase even further. As a good practice, if the discharge valve is not MV, keep it closed at start up and after wards open slowly. Teflon bearings in... [ 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
Alup Positive Air Pressure, Air Compressor Over temp
Registered Member Hey Scoota, Great another Kiwi on here!! I am glad it wasn't my compressor hahah! it least they happy now it all fixed. I am down in Auckland work for a consulting company. I was up to your place up in Marsden Point last year, (April I think) when you had a problem with one of your Cooper Turbo Compressors.Small world!! What do you do up there? Cheers [ more ]
Registered Member Hey Kiwi, Good find! were they disapointed it came after the new cooling system was installed? Where abouts in NZ are you located? Im up in Whangarei at the NZ refining company. Nice to know there are some fellow Kiwi's around here. [ more ]
Registered Member hey mate! We sort of sat down and thought what the hell could be causing it. we had checked everything else so we thought lets have another look at the system and ..Bingo [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Cracks/failure of shaft
Registered Member I would like to follow up to support more generally the conclusion that misalignment will create less bending stress near outboard bearing than inboard. Attached is analysis of modeling of a wide range of shaft to shaft misalignment conditions. There are four variables: Shaft, Coupling, Bearing, Misalignment. Each of these variables is varied in two configurations: Shaft is thin or thick. Coupling is hard (stiff) or soft (flexible). Bearing is hard (stiff) or soft (flexible). Misalignment is... [ more ]
Registered Member I agree with the others that the cause is likely to be stress concentration of some type. We can support this conclusion by studying the loading present at the location of the failure. The failure occured where spider ends at the OUTBOARD end of the motor shaft. What kinds of stress are present at that location?: 1 - Torsional? None. There is no torque transmitted from the spider outward. 2 - Axial? None. This is a large motor so I assume sleeve bearings, which cannot give axial restraint. 3... [ more ]
Registered Member When the spider was welded to the shaft they made one big mistake that probably caused this shaft to crack. Welding the ribs of the spider to the shaft is fine as long as you are parallel to the shaft, when they welded the rib ends to the shaft is probably what caused this. When I was in the motor shop and a rotor come in with this we would sometime machine the weld out and relieve this point. More than likey this crack was from the stress risers created by welding the ends of the ribs to... [ 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
bearing failure
Registered Member Astroboy 1st Make sure that you did not have 2 held bearings on this fan. 2nd Was the bearing outer ring in the center of housing when you pulled bearing cap. 3rd If this bearing had a taperd sleeve - check the sleeve for proper taper. The Inner Ring fit on the shaft or sleeve will tell you if fit was correct. Mark alertanalytical.com [ more ]
Registered Member Hi Are any other fans running at interfalls to create change in ventilation velocities? [ more ]
Registered Member The one obvious issue here is this bearing presents itself as if the shaft was mounted vertically. That being said its not a big leap to say, that being a fan the shaft is horizontal, and the bearing has been exposed to a high axial load. Perhaps this has been caused by shaft expansion? What does the load path look like on the outer ring? the other side of the inner ring shows signs of pitting, possibly dirty oil caused by the wearing of the other side of the raceway. My initial thoughts are... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
piston melts
Registered Member what about your pre-conclusion as of now. by now you should have some sort of hypothesis since you have full picture on the issue at site. share what you think with us [ more ]
Registered Member thank you very much guys for you'r opinion, i really appreciate it. still looking for more. [ more ]
Registered Member valve is right,Lack of lubrication is the culprit, [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
fire pump engine
Registered Member Is this a new installation? If it is not new and has been running fine for some time I would think you can safetly rule out the discharge head being to high for the pump. If it is an old installation your cooling jackets can become blocked with mineral deposits/sludge, so even though your strainer may be clean you will not get the heat transfer through the engine. It would be a good idea to visually check the amount of cooling water being discharge to tank if possible then you can be sure... [ more ]
Registered Member thank you very much vibmaster for your time, any way, just for your info. I am a technician working for generator set here in the philippines, i am also not an engineer, so i hope you'll you can relate to me on the way you think it should be. In our company, we usually attend on generator problem and doing PM as well on various customers. We also covering maintenance work on firepump engine, for it was driven by an engine specially cummins engine where we are specialized, For so many years... [ more ]
Registered Member What is the discharge pressure of the pump? Can you check the flow through the jacket as well as temperature of inlet/outlet lines and compare with the other pump? I am talking of strainer provided in the cooling line to jacket and not of pump suction strainer? We have to clean the strainer frequently other wise if it gets clogged and reduces flow. How long have you been facing this problem? Vibmaster [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Thomassen Recip with no tempered water HAZOP
Registered Member During normal running, the piston is floating on gas bearing instead of rider rings. Rider rings come into play only during start up and stop. so, rider rings wear will not be an issue. Vibmaster [ more ]
Registered Member Thanks for the reply guys. Yes this is a cooling/tempered water circuit. The water is kept about 6DegC above inlet temp of the hydrogen to prevent liquid drop out in the cylinders. The head and cylinder jackets are all on the same loop. We have three identical machines all running to common headers, previously it was only possible to isolate individual cylinders. Recently we had to undertake fairly major foundation repairs which made it necessary to be able to isolate one complete machine... [ more ]
Registered Member Cylinder head temperature will increase. Normally, the material being Cast Iron, chances of crack developing are there. Is there separate loop for cylinder head and jacket? Normally, the loops are same and isolation of cylinder head means isolation of jacket as well? Vibmaster [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
High frequency impact peaks on motor bearing failure
Registered Member In data logger resolution on raw mode can't be changed. Sensors are with magnets and upper frequency 10 kHz. Rest of data existing after 10 kHz is probable ghost information - it is not real. Dynamic and fastening of sensors will not give reliable information definitely after 10 kHz. Poor lubrication is possible. [ more ]
Registered Member To reply at a basic level. At first glance at your data it appears to be a dry or under lubricated bearing. The data quality lacks resolution. 800 lines/50,000Hz in my opinion is too few lines and higher than necessary Fmax. There appears to be not much happening beyond 12KHz. Can you take data at 12,000Hz Fmax and 6400lines? and also post the W/forms? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Stator core repair problem
Registered Member It sounds to me that the stator and rotor are probably junk at this point. You can't turn the rotor down to reach better iron, you're messing with iron densities. The stator will need to be re-stacked and rewound. [ more ]
Registered Member Here are a couple of possibilities... http://www.kellerelectrical.co...repairdivision.shtml http://www.insulcoresolutions....nsulcoreprocess.html Dave [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Bearing NU2256 failure
Registered Member It is the only marck on the bering. Attached you can see also the rolls and the iner ring. [ more ]
Registered Member The original root cause is difficult to determine. Whatever caused the initial defect later spalled during running, and corroded from water contamination. The root cause may have been horrible corrosion from water ingress, brinell denting, or maybe even dragging damage from inserting rollers into the raceway. Are there similar ball-spaced indications on the raceway or is this the only spot like this? [ more ]
Registered Member Water and/or hard particle contamination would be my first thought [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
outer ring failure
Registered Member What you're seeing is overlapping roller-spaced damage. This bearing sat unrun multiple times. Each time the bearing stopped running, it stopped at a random location and the rollers left brinell fretting marks. [ more ]
Registered Member False brinelling is simply the rolling element marking the raceway. if you see false brinelling at roller spacing, and no where else, you know some impacting is occurring whilst the machine is at rest ie. bearing isn't rotating or the impacting is occurring in phase with the machine. If it is occurring 'randomly', it is not actually random, something is causing the rolling elements to mark the raceway at a frequency out of phase to the machine. a simple example is someone hitting the machine... [ more ]
Registered Member Thx dave for your input, your justification sound very logic, the photo for the 5 years old Brg. important information!, the inner race has also these random marking in axial direction (100% of the inner race), the roller very light axial marking, not sensable by finger Could be true Brinneling due to impacts ? , M2H was 0.16 IPS at 1x Could be true Brinneling due to impacts ? - M2H was 0.16 IPS, the history of M2H was about 0.06 IPS this motor runs continously it stops only within shoutdown... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
XE04 MDO fast roll #22
Registered Member Honestly, the failure is too far advanced to tell what happened from the pictures. The races appear to have uniform debris denting on the surfaces. You would need the grease sent to a lab where contaminants could be extracted and characterized using SEM/EDS methods. What is the bearing application? What is the lube maintenance history of this bearing? The bearing may have locked, which resulted in spinning of the bearing on the shaft. Lube failure often results in a shiny, mirror-like finish... [ 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
Angular contact Ball Bearing FAG 7218-B
Registered Member Be careful while installing the thrust bearing you have to install it in right direction otherwise your bearing immediately it will fail and the temperature it will shoot up fast. If you see the bearing cage shape almost tapered in that side you have to install the bearing in that direction and you have go through motor manual for more sure. [ more ]
Registered Member Yep, that's exactly what I understood you were saying. Just reinforcing with a picture. [ more ]
Registered Member The arrangement in the drawing is same as I mentioned. Irshad [ 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
steam turbine front radial bearng frequent damage
Registered Member Dear all, Thanks your response. Sorry for late to re-post the attachement. One and half months ago we finally resolved the high temperature issue . The root cause is due to coupling guard blocking the bearing house expansion and a loose bolt on the guiding support of the bearing house. Thanks lux [ more ]
Registered Member This is a very small file size for a power point presentation (PPT), so it is probably corrupt. Try attaching file again after verifying the file is complete. Walt [ more ]
Registered Member because it is from china, will not open. Hence, please create a PDF format and attach it [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
beaking bolts of sag mill
Registered Member Improper and (more important) inconsistent bolt preload could certainly be a major part of the problem. However, there could also be other contributing factors involved. Nevertheless, if the prime cause is the former, the solution is going to require much more than the millwrights simply rattling the bolts more with the impact wrench. First, one has to know the range of preload that one is getting using existing methods. This takes a bit of effort but can be done fairly quickly. Then, if... [ more ]
Registered Member Lets see if I got this rite. So plates welding themselves inplace would be structural failure or too small / undertorqued bolts allowing plate walk? Yeah I toured the plant already its huge, has a massive rotary kiln also. [ more ]
Registered Member @just - Some of these beasts can be quite large; SAG mills of 42' diameter are no longer just a dream. Here are a few things to keep in mind when you transfer: Bolts are critical mill components. A common but often misunderstood problem is breakage of not only liner Bolts but also of the structural bolts. When a mill throws a joint bolt, it usually result in a forced shutdown. Fatigue failure due to high dynamic loading and incorrect preload is often the root cause. However, in some of our... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
damaged on the steam tubine shaft end thread
Registered Member Lux, On mounting process the adaptor must be complete in contact with the shaft frontal face, which will undertake the axial force induced when remove/install the hub. If the adaptor was not screwed complete and it face was not in contact with shaft face, the hole axial force will be taken only by threat, which is not designed for the entire axial force. The adaptor thread should be longer as shaft thread. Also it is necessary to check if the clerances between adaptor thread and shaft thread... [ more ]
Registered Member I have not had much experience with this hub installation process, but would like to know if there is a recommended sequence to be fallowed when pressuring up the hub? Could pressuring the push side before the expansion side cause fluid hammer when the hub moves? [ more ]
Registered Member Hi valve and all, Attached is material inspection report from third party. From report view it is ok , no abnormalities were found. So at present , we had to again review whole coupling mounting process (coupling installation and removal using two hydraulic pumps). And discussed it with Siemens site service guys. The only difference between us is the "start" installation position of coupling . In my mind the "start" installation of coupling is a location when setting hub on the shaft and... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
bearing wear
Registered Member what about lube oil quality check. cleanliness check and ferrous or non-ferrous element from ferroghrapghy check. Furthermore, do you monitor the vibration symptom before it failure. Seemingly like rubbing and sliding effect. [ more ]
Registered Member Seems like metal to metal problem.what just happen? [ more ]
Registered Member It is difficult to tell from the picture but it looks like there is some abrasive wear. It looks minor to me but a clearance check should tell if the amount is excessive. [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Plummer block with special seal dedicated for metal rolling mill degreasing line
Registered Member If i were to decide since problems keep repeating 3-4 days???I would change to oiled bearings with labyrinth seals. [ more ]
Registered Member I am maintenance manager of a hot-mill strip steel mill but we have cold-rolling strip steel mill plant let me know what about machine exactly. I can talk about it by my coworkers in our cold mill plant [ more ]
Registered Member Nice find there GLT! That should do it. Ill bet the Baker guy in other post could use them. You wouldnt believe the wear flour salt and other bakery dusts cause, add the routine hot wash down with caustic soda. Believe me its a constant battle every week. [ more ]
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