Please could anyone advice me a LAB in Middle east or Europe where they are conducting tests to estimate Varnish effect on Gas Turbine Lube oil.
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I'm no UOA tech but I'm not even sure there is a "Varnish effect" test. You might want to give WearCheck a call and ask them what they would suggest. They have lab's all over the world inclucing the UK and ***many. I have used their USA lab for years and am happy with their service. Any time I had a technical question they were very helpful. http://www.wearcheck.com/contact/global_contact.asp
At the bottom of this page is a sample Industrial 2 and Industrial 3 UOA that should give you a idea of what their UOA's look like.
At the bottom of this page is a sample Industrial 2 and Industrial 3 UOA that should give you a idea of what their UOA's look like.
Due to the problem with varnish formation in turbine oils, especially those using Group II basestocks, there are definitely varnish potential tests. Analysts has one, WearCheck may have one, several labs have developed or are developing. ASTM has a working group developing an ASTM method based on color of material filtered onto a patch to deal with problem. ASTM held a symposium last year on problem and techniques being used to detect or better yet predict it - loss of phenol antioxidants seems to correlate with initiation of varnish especially when amine antioxidants are also in formulation. Greg Livingston has several links under oil analysis link, Andy Sitton also has some links describing problem.
www.focuslab.co.th/pdf/JFS_ResidueAnalysisonRPVOTtestsampesforsingleandm.pdf
Paper by Focus labs located in Thailand - not sure if that meets geography you were looking for
This is one of the ASTM papers invo**ed with varnish potential of turbine oils. Also shows RPVOT measures remaining oxidative life of oils with just phenols (older formulations) much better than those with phenol/amine combinations (newer formulations)
Paper by Focus labs located in Thailand - not sure if that meets geography you were looking for
This is one of the ASTM papers invo**ed with varnish potential of turbine oils. Also shows RPVOT measures remaining oxidative life of oils with just phenols (older formulations) much better than those with phenol/amine combinations (newer formulations)
We have been working with Analysts, for QSA tests and RPVOT. Of course, the lab is not in the middle east or europe. But I am from Canada and we don't have any problem shipping the used oil to the lab and the responce time is more than acceptable.
I am sorry, but I am not convinced that analysis of varnish potential has any value at all. I see folks giving great accolades to it, but nobody elaborates on usefulness of it and the follow up action to better it up. It is logical and undisputed that every oil tend to form varnish when in service; some more (group 2) than others (group 1). Knowing this, everyone that cares about his/her oil will employ some meaningful filtration system to keep varnish in check. If one does that, what practical value "varnish potential" test has, because there are no additives to add that would cure the oil showing positive potential. Also, how results are reported and who sets ranges (good to terrible) of this "potential" (individual labs setting their own or some standard organization like ASTM)? Are those ranges the same for gear oils, turbine oils, transformer fluids, hydraulic fluids, etc.? Nobody talks about practical aspect of this analysis and needed remedial actions following the testing. This “phenomena” reminds me of the hype about another “si**er bullet” – the electrostatic filters. The fact is, they are OK, but they don’t do anything that “classical” filtration cannot do equally or better in certain situations. Can someone shine some light on it?
You are right in a sense since once the oil starts to produce varnish, filtering simply removes the micron sized insolubles but doesn't stop their production. So as the rate or potential increases, the filtering is in a losing battle. The work I have seen - ASTM symposium - says that when the phenol antioxidants deplete, the varnish starts regardless of the amine antioxidants still in the oil. The amount of varnish that forms depends on the so**ency capability of the oil. Group 1 oils with phenol antioxidants - no varnish problems since when phenols deplete, RPVOT decreases, acid increases, and oil is able to keep the oxidation products soluble until RPVOT/AN limits have been reached. Group 2 oils with phenol/amine additive package - phenols deplete, RPVOT and AN don't respond since amine antioxidants still present allowing oxidation to occur but not at the expotential oxidation rate required to set off alarms, poorer so**ency of base 2 oil can't keep oxidation products soluble - also amine antioxidants can contribute to deposit/sludge - and varnish builds in group 2 both due to antioxidants and so**ency differences. So based on this you should monitor your oil for varnish potential with two techniques - one to monitor phenol depletion (e.g.,voltammetry)and other to monitor varnish potential since potential/so**ency will differ between basestocks. When phenols deplete -replenish with phenol only additive - filter to keep potential minimal. Using the two techniques, the varnish test has value and will allow you to extend the useful life of the oil without the risk of varnish until the RPVOT/AN increase due to loss of amine antioxidants.
Thank you Bob for nicely summing up much what has been written about measuring “varnish potential”. However, I still think that this method is too academic and fancy, and is not helpful to end-user at all. What it does is, it measures "potential" and refers to "trend", but does not express anything in exact values. I would like to know how many people who deal with oils on every day basis are not aware of the "potential" that their oil will varnish once in service? Do they need to test it to be told what they already know, and what is perfectly logical:..."yeah, your oil exhibit "potential" to produce varnish of X points on the scale of XXX points” (?). In addition, it seems that there could be only two remedial actions, providing that someone's housekeeping include use of a meaningful filtration system. One, to readditized the oil (as you suggested), and second, to condemn the oil and dump it. I have serious problems with both.
1. Readditizing turbine oils, on its face, is not recommended step by anyone I've talked to from oil manufacturers/blenders world. There are several things why this approach is not recommended:
a) Additives in turbine oils are delicately and meticulously balanced, and possible under- or over-additizing can negatively affect oil’s characteristics (demulsibility, foaming and air release first come to mind)
b) Every time one tries to add something to the oil (despite oil manufacturer’s warnings and recommendations), there is always looming danger of mixing incompatible additives (between new and ones already in oil). Choosing the right additive could be very, very tricky, because there are not only one kind of phenolic and amine based antioxidants out there on the market.
c) Process of adding additives efficiently and in the right amount to the oil is additionally complicated by low so**ency of the oil where the added additive should disso**e (providing that one deals with group2 oil, which is more than likely the case since these oils exhibit greater “varnish potential”).
d) This process also requires use of additional conditions (e.g temperature and mixing equipment) to make sure that additives will be completely and evenly distributed/blended throughout the entire bulk of oil. There is a huge problem with logistics of such approach, if, for example, the bulk of 60,000 gal of oil is contained in individual and not inter-connected sumps, and each containing from 400 gal to approx. 2,500 gal. It is impossible to do it without stopping the whole plant or at least part of it, drain the oil back to main storage tanks, somehow readditized it (at least put up the best effort), and pumping it back to sumps (e.g. thrust bearings, guide bearing, governor and accumulator tanks, and turbine hubs if one operates Kaplan turbines). Let as don’t even think of the amount of non-additized oil that did not get drained out when we attempted to do so, and how it would affect the final desired outcome once it get mixed in, and necessary extended downtime, which would cause enormous financial drains during such effort.
e) After all this work and endured expense, I am almost certain, such readditized oil would sooner rather than later again showing “varnish potential”.
2. I would never accept, nor suggest to anyone, to go ahead and replace entire bulk of oil, just because it showed “varnishing potential”.
Note to all posters: Please don’t take my remarks as offensive, because that was not my intention. My only intention is to ask your assistance in understanding the practical benefit(s) of this test method. I hope I am not the only one needing to touch the bottom line.
1. Readditizing turbine oils, on its face, is not recommended step by anyone I've talked to from oil manufacturers/blenders world. There are several things why this approach is not recommended:
a) Additives in turbine oils are delicately and meticulously balanced, and possible under- or over-additizing can negatively affect oil’s characteristics (demulsibility, foaming and air release first come to mind)
b) Every time one tries to add something to the oil (despite oil manufacturer’s warnings and recommendations), there is always looming danger of mixing incompatible additives (between new and ones already in oil). Choosing the right additive could be very, very tricky, because there are not only one kind of phenolic and amine based antioxidants out there on the market.
c) Process of adding additives efficiently and in the right amount to the oil is additionally complicated by low so**ency of the oil where the added additive should disso**e (providing that one deals with group2 oil, which is more than likely the case since these oils exhibit greater “varnish potential”).
d) This process also requires use of additional conditions (e.g temperature and mixing equipment) to make sure that additives will be completely and evenly distributed/blended throughout the entire bulk of oil. There is a huge problem with logistics of such approach, if, for example, the bulk of 60,000 gal of oil is contained in individual and not inter-connected sumps, and each containing from 400 gal to approx. 2,500 gal. It is impossible to do it without stopping the whole plant or at least part of it, drain the oil back to main storage tanks, somehow readditized it (at least put up the best effort), and pumping it back to sumps (e.g. thrust bearings, guide bearing, governor and accumulator tanks, and turbine hubs if one operates Kaplan turbines). Let as don’t even think of the amount of non-additized oil that did not get drained out when we attempted to do so, and how it would affect the final desired outcome once it get mixed in, and necessary extended downtime, which would cause enormous financial drains during such effort.
e) After all this work and endured expense, I am almost certain, such readditized oil would sooner rather than later again showing “varnish potential”.
2. I would never accept, nor suggest to anyone, to go ahead and replace entire bulk of oil, just because it showed “varnishing potential”.
Note to all posters: Please don’t take my remarks as offensive, because that was not my intention. My only intention is to ask your assistance in understanding the practical benefit(s) of this test method. I hope I am not the only one needing to touch the bottom line.
I am a researcher but do realize there are many difficulties when trying to scale up lab experiments to industrial processes. Obviously these procedures would have to be tested out on the large scale by oil/additive companies with the assistance of equipment/plant personnel.
The comment of carefully balanced additives I have always found puzzling - obviously over additization must be advoided - but used oils' additive systems are quite different from their fresh oils and are affected by application (Group 1 used in gas turbines - phenols deplete, corrosion inhibitors unaffected but when used in steam turbines - corrosion inhibitors deplete, phenol unaffected), mixing of different manufacturers using different additve ratios, different batches having different amounts. Sometimes additives change with time: there are numerous turbines that were originally filled with Group 1 oils containing only phenols getting topped off with Group 1 oils containing phenol/amine antioxidants. For years people have put ZDDP additives in car oils for longer life, better performance. Have seen transformer oils where new oils contain 10% of the antioxidants in the used oils since the antioxidants were not depleting.
So if the replenishment of the phenols was shown to minimze the varnish problem while extending oil life would think some enterprising people could find a way to get around the difficulties you detail.
One other item: it is my understanding the varnish potential is being written into an ASTM method to give the user some standards to compare against.
si**er - wanted to see if "l" and "v" come out as ** - as happened before
The comment of carefully balanced additives I have always found puzzling - obviously over additization must be advoided - but used oils' additive systems are quite different from their fresh oils and are affected by application (Group 1 used in gas turbines - phenols deplete, corrosion inhibitors unaffected but when used in steam turbines - corrosion inhibitors deplete, phenol unaffected), mixing of different manufacturers using different additve ratios, different batches having different amounts. Sometimes additives change with time: there are numerous turbines that were originally filled with Group 1 oils containing only phenols getting topped off with Group 1 oils containing phenol/amine antioxidants. For years people have put ZDDP additives in car oils for longer life, better performance. Have seen transformer oils where new oils contain 10% of the antioxidants in the used oils since the antioxidants were not depleting.
So if the replenishment of the phenols was shown to minimze the varnish problem while extending oil life would think some enterprising people could find a way to get around the difficulties you detail.
One other item: it is my understanding the varnish potential is being written into an ASTM method to give the user some standards to compare against.
si**er - wanted to see if "l" and "v" come out as ** - as happened before
is ther some hidden meaning to "l v" that I am unaware of?
si**er disso**e so**ency invo**ed
si**er disso**e so**ency invo**ed
Bob - I agree with all of your points. Measuring phenols and amines are a key part to understanding a fluid's degradation and when varnish will start to become a problem. RULER should be part of any turbine oil condition monitoring program.
John - you are correct; it is very complex to mix additives in used turbine oils. There won't be a single oil company that will support such efforts. That being said, reformulating phenolic antioxidants as Bob suggests has no inherent risks if it is done by an experienced formulator. There is much research that is going on in this field and the data is convincing. If done properly, this is a safer practice than topping up used turbine oils with a product of different additive chemistry as there are many new additive components that may be incompatible, like corrosion inhibitors and foam inhibitors. This practice is done in the field all the time without concern.
The risks with additive replenishment are real and should be taken seriously. However, one must realize that the oil companies, who do a phenomenal job of creating mystic about their oil formulations, do not have a business case for participating in additive repenishment. This doesn't help their bottom line...and the last time I checked, their bottom lines aren't doing too badly.
John - you are correct; it is very complex to mix additives in used turbine oils. There won't be a single oil company that will support such efforts. That being said, reformulating phenolic antioxidants as Bob suggests has no inherent risks if it is done by an experienced formulator. There is much research that is going on in this field and the data is convincing. If done properly, this is a safer practice than topping up used turbine oils with a product of different additive chemistry as there are many new additive components that may be incompatible, like corrosion inhibitors and foam inhibitors. This practice is done in the field all the time without concern.
The risks with additive replenishment are real and should be taken seriously. However, one must realize that the oil companies, who do a phenomenal job of creating mystic about their oil formulations, do not have a business case for participating in additive repenishment. This doesn't help their bottom line...and the last time I checked, their bottom lines aren't doing too badly.
