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Reliability Engineering for MaintenancePosts about Root Cause Analysis
what is the difference between root analysis and common analysis
Registered Member I haven't heard of "root analysis" or "common analysis". I would guess that maybe the two terms you wanted to address were "root cause analysis" and "common cause analysis" Root cause analysis was discussed above. It attempts to establish the fundamental cause of a single event. Common cause analysis examines many events at a given facility or company and attempts to identify whether there is a small group of factors that contributed to most of the events ((common causes). Factors which... [ more ]
Registered Member I think the term you're addressing is: Root Cause Analysis which is the problem's source. Common analysis may take on a variety of subjects but in the vibration world it may be: PdM route analyses which may entail exception reports and/or basic approches to spotting trouble - or vibration trouble-shooting which should take on a set pattern of data collection and information gathering utilizing more advanced techniques or more complex methods that also incorporate RCA (root cause analysis)... [ more ]
Registered Member China Girl, I believe these two terms should be addressed to a computer programmer or someone with programming knowledge. Both root and common analysis are used in program development and its sub-routines. However, if you are referring to root cause analysis (RCA) and common analysis. The difference is, RCA is a problem solving process that engages various tools to identify and resolve the origin of a problem; while common analysis is used to identify failure rates and mechanism in software... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
Sundyne oil pump failures
Registered Member Thanks for the reply. I also discovered the metallurgy of the pump shaft has changed. It is softer than the drive pins. [ more ]
Registered Member Yes, I also had this problem with cotter pin. Also I had once obserevd that the oil pump seazed due to improper air venting from the system. actually the vent was chocked and operating temerature was high. [ more ]
Registered Member Frank, One of the main problems with these p[umps is the drive pin. Sundyne is using a cheap cotter pin, which is getting damaged during pump starts due to impact forces. I indicated this issue to Sundyne management about 7 years ago and they stated that I was the first one complianing about it. Many of my counterparts in different facilities throughout the US had the same issues. We corrected it by replacing these pins every time the gearbox is opened and adding auxiliary oil pump on auto ... [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
75kW PUMP MALFUNCTION - SUPPORT REQUESTED
Registered Member What is the distance from the power supply to the pump? What is the cable (wire) size? What is the voltage at the power supply, itself? What is the nameplate voltage and current for the pump? Howard [ more ]
Registered Member What is the nameplate speed rating and what speed is the machine actually running? [ more ]
Registered Member Vmac, So you have lower starting & running currents? This is quite strange. Normally people use soft starter to reduce starting current but your problem is the reverse. Read here about what is a pump diffuser: http://www.engineersedge.com/pumps/diffuser.htm Rennie, did you mean the diffuser vanes got worn out and their lower halves broken off or detached from the impeller? Vmac, even though the pump still evacuates water, is it at the right discharge pressure & flow rate? [ more ]
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Reliability Engineering for MaintenancePosts about Root Cause Analysis
5 Whys
Registered Member This is the article. I sharpened the best practice using the documents cited in the bibliography, which are free to download. The purpose of the best practice, in the previous post, was to push the concept of RCA down to the floor level. Howard [ more ]
Registered Member Mike: Here is the sanitized best practice. In the actual best practice, the first step is to determine if the problem is safety related, has a production value over a certain value or is on equipment over a certain value (as well as a few other requirements of the company). If they exceed the selected requirements, they are shunted over to another, more complex, RCA system which requires corporate engineering. In my travels, I will use the five why system that I am outlining here as a quick... [ more ]
Registered Member Terrence, The 5-Whys is a well established RCA methodology, but it is not much favored by the Gurus of the Root Cause Analysis methodology. Mike points out some of its structural weaknesses. It is a simple technique very suitable for the less complex problems and hence for the shop floor. [ 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
Where does the problem live?
Registered Member Thanks Phil, that's a lot clearer now for me. ....i like the website & articles. cheers Rennie [ more ]
Registered Member Rennie, I do not take any offence from your comments, let me try to explain what I was saying. In your note you said: But I can't understand how, if these people were logical thinkers and had good technical skills, they missed the "good maintenance practices". What they did was focus on finding a 'silver bullet', the technical breakthrough that would 'solve all their problems'. This focus blinded them to the management approach that they should have applied. Worse than this, if asked, they... [ more ]
Registered Member I go to the source and analyze the failure and work backward from there. I do only machines and not people. If the fault was lack of training, so beit! No one is at fault: a problem exists - fix it and move on. Finding underlying causes and removing them so the problem does re-occur is a mark of success IMHO. [ 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
RCFA Basic Steps
Registered Member Hello All, RCFA is always recommended for a group of people involved in the asset, Fractography, failure analysis, can be done by a single person with extensive knowledge on the aspect. Shoul I perform an RCFA investigation team, I'll place an operations, maintenance, PM person, PdM person and even contractors if third party is involved. My Warm Regards, Rolly Angeles Teacher [ more ]
Registered Member I gladly welcome the input from anyone with deep knowledge on the equipment operation, maintenance, failures and performance. If the maintenance organization has a PdM team (even a team of 1), their (his/her) participation in the RCFA group would be valuable. [ more ]
Registered Member Eugene, what about having the PdM guy/girl on the RCFA group if available? Seems like one more perspective on the equipment would be valuable. Have to admit a vested interest, that is my current postiton & I am trying to get a formal RCFA program started here. [ 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
RCA for a broken down submissible pump
Registered Member What can cause journal bearings inside a motor to fail? [ more ]
Registered Member Point noted. I agree that the nearest people should know better. However, sometimes it opens the mind a bit by listening to external views at the brainstorming stage. [ more ]
Registered Member Josh, I understand you and your colleagues have had formal RCA training recently. The best people to understand your pump failure are your own operating and maintenance staff, not some of us guessing from 000.s of miles away. Others can tell what they found in their situation, but that may not apply in your case. All they can suggest is a laundry list of failure modes for you to investigate. With these provisos, it would appear from the pictures that you might have had a lubrication failure. [ more ]
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