I have three turbine consoles with Mobil DTE 797 Turbine oil. What is the recommended ISO Code. Thanks Thomas

Bently Nevada Orbit 4th Quarter 1999 (available free on-line) has an article from Dave Whitefield "Clean up your oil and keep it clean". He recommends 17/15/12 for journal bearings and 18/15/12 for steam turbines (I'm not sure why a separate higher number for steam turbines).

I have an SKF publication which lists 18/15/12 for journal bearings.

I'm pretty sure Jim Fitch has made some recommendations at machinerylubrication.com but I don't have a link.

I think the way to go is to establish where you are now and set a target. In my case we have a GE 1800RPM 14-stage turbine generator with oil that historically runs clean and water free. We have a very efficient oil conditioner and an Operations staff that pays good attention to oil condition. We centrifuge every outage also so my target is 16/14/12.
rgf

we have some geothermal power plants here in the philippines and have established some oil analysis program but almost always we encountered contaminated oil due to corrosive environment caused by hydrogen sulfide/silica/and water contamination. we use the oil tribology concept.
but to come up with cleanliness standard we are at a loss. Do we need a particle counter to check the cleanliness of the oil?
pls recommend what type of equipment to use. most probably a portable one so we can bring the test equip at diff. site/plant.
thanks for any reply.

ianski,
I am not an expert by any stretch and I am not familiar with your application but all my research on this topic indicates the cleanliness target really should be a function of the components in the system (eg very fine clearance valves need cleaner oil than gear pumps, for example).

I found a couple of good references here:
http://hydraulics.eaton.com/products/filtration.htm
Look for the "Target Cleanliness Worksheet" and "The Systemic Approach to Contamination Control" links on that page.

In terms of portable automatic particle counters, we have had good results with the Pamas S40.

We have also done some investigation into patch testing because an automatic particle counter will obviously count water, additives agglomeration, bubbles etc and in our application seems to give us a result that is 1-2 ISO codes higher than patch tests and comparator photos.

Thomas,

The first place to start is with your turbine manual. For example, for large GE steam turbines, the GEK manual has cleanliness limits for operation and for lift pumps. The reason is that when the unit is on lift pumps, the clearances in the journal bearings are smaller, so the cleanliness requirements are tighter. These limits should be part of a procedure that lays out the proper sampling technique, the frequency of testing, and what specific actions and timeliness of those actions when a limit is exceeded. Typically, during an outage, plants want to reach the "lift pump" limit as a minimum level of cleanliness before putting the unit online. If the unit is online, and an operating sample is taken, there needs to be very clear guidelines on what steps are taken if the "operating" limits are exceeded (typically immediate shutdown of the turbine is not the standard practice!). Corrective actions include evaluation of online purification systems, use of supplemental filtration systems, and sometimes an ultimate limit for preventing operation to avoid serious damage.

Some of the other replies here are actually talking about "targets". In addition to operating limits, targets are even tighter values that the facility tries to achieve to reduce the rate of wear of system components, and extend oil life. The cleaner the oil, the longer the lubricant will last and the less damage that will be inflicted on the lubricated parts. Finding out what your current cleanliness levels are, ensuring that your sampling and analysis methods are proper and consistent, is the starting point for establishing targets. As a lubrication program matures, cleanliness targets should be re-evaluated and adjusted to continually improve machine performance.

Rich Wurzbach
CLS, OMA-1, LLA-1
MRG Power Labs
MRG Power Labs

Dear all,
I am not an oil specialist however I need to learn something and maybe some guys out there can help.
I have seen that for hydraulic oil systems the acceptable impurity level is specified and expressed in a contamination code according to ISO4406 par example like this: 17/15/11 and this seems to refer to 4 micron/6micron/14 micron contamination traps. (Also equivalent to NAS1638 class 6). I have seen also that such hydraulic systems are equiped with an oil filter with a 10 micron filtration grade.
My question Q1 is: how can class 6 be maintained during operation if the oil filter is 10 micron, taking into account that during operational life internal wear will produce particals smaller than 10 microns?
Or in other words Q2: at initial filling of oil into a tank, why should this oil contain no, or limited amount, particals of 4 .. 6 microns while we know that these particals will inevitably be produced by internal wear and never be trapped by a 10 micron oil filter?
Q3: Doesn't the nature of the contamination make any difference, aluminium, (stainless) steel, carbon, etc.?
Regards,
Arie Mol, NL

Who do recommend the cleanliness? It's the manufacturer, and why do they do it?
1: Because they want to deliver a lot of parts and work when equipment fails.
2: There has not been systems that can clean the oils lower than about 14/12/10.

In my opinion the goal should be as low as possible, to save money and increase the lifetime of the equipment for you.
-Or what do you say to a hydraulic oil with a lifetime of 18000 (eighteen thousand) hours by today. And still in use and cleaner than "new oil"!
-A marine engine, Volvo Penta 400 HP, has been in use for more than 40000 hours without any oilchange, and the oil still in good shape.
-A wellknown oilcompany saves handling of about 70 000 l of oils a year, because they do clean the oil where the oils are. And have saved this for many years.
These companies, amongst many more, have taken our oilcelaning system in use and have seen results in saving money, increased lifetime and safety.

A lot of companies; Shell, SKF, GM, Statoil, and more, say that it is importent to have an oil as clean as possible. I agree with that but I don't talk about ISO4406 14/12 or 15/13. I talk about lower than 10/7! So you as a customer should demand better filtersystems and cleaner oils when buying.

Arie,
Again I am not an expert, but as far as I can tell, "10 micron filter" can mean just about anything. I would be inclined to call in a reputable vendor to help select an appropriate filter media and element size to maintain the cleanliness you want.

Consider a 10 micron filter is not a 10 micron mesh screen for example, so it is probably not as simple as saying 4-6 micron debris will pass through the element.

In terms of contamination type, again as far as I can tell from my reading, yes, the hardness of the contaminate has an impact on the rate of wear.

I found a lot of educational reading at the National Fluid Power Association website. They post all their conference proceedings at no cost:
http://www.nfpa.com/Tech_Papers/search_techpapers2000.asp

Regards,
Matt.

Kjell,
I work in product support for an equipment vendor. Our company is always working on improving equipment reliability with the view of lowering life cycle cost. Failures are nothing but downside for our customers and subsequently our reputation.

We see improved oil filtration as a valid activity to extend the life of wet compartments, so I would be interested whether there is anything I can learn from your experience to share with our engineering people.

However, just like any business, we need to justify a case for spending engineering money, so any cost for improved filtration must be offset by the probability of lowering our customer's life cycle cost. It is easy to say "as low as possible" but it is often difficult to verify the benefit of doing so.

Would you be prepared to share details of the examples given? Specifically 18,000 hour hydraulic oil and 40,000 hour engine oil?

Also, by which method do you measure oil contamination at levels as low as -/10/7?

Regards, Matt.

Matt McLeod
First of all I have to confess: I am an agent for this system. But all I'm telling you is from the real world, we have nothing to do with the statements of use. This comes from our customers themselves.
1: It's a norwegian researchinstitute that have this oil in use. (18000 hours)
2: Here it is a swedish public ship-owner. (40000 hours)

In both cases they use ordinary ISO4406 with two levels, but they use more than one sample. They then recieves trendresults.
Additional they use microporefilter of 0,8, 0,45 and 0,22 micron to confirm the cleanliness. When you cannot see any particles or anything else on this microporefilters, you can be sure that the oil is clean down to the level of at least 0,22 micron.

It's also important to tell that an oilcompany asked an unindependece analysingcompany to count all particles from 0 and up to find where the dirt are. The result showed that 98% of the particles are below 5 micron! That means that a filter of "absolute" 2 micron will be in ISO4406 cl 0/0. But none of them are, the best are class 14/12, as far as I have seen. This show us that they are just a little bit better than ordinary componentfilters.

The Oil is like "blood" for the machines and the equipment. Therefore it is important to keep the oil in a good condition during the whole lifespan to be able to perform its vital duty. If the oil is incapable to do so, technical problems or unwanted operation will sooner or later be the case.
The oxidising of the oil is a mechanical + chemical process witch continusly is going on. This process is dependent of oxygen but also of how much energy that is added while operating. Energy or temperature is added as friction. The more energy, the faster the oil is oxidising.
Both hard and slimy depositions are created, (Varnish). In an engine/motor, oxidised oil leads to different depositions that can initiate a break down.
In an hydraulic system oxidation can lead to restriction in oil flow, power loss, sticking valves, shortage in solenoid valves, cavitations, seizure of system components, corrosion, pitting.
Oxidation pollution products in the oil often results in unpredictable and unnecessary stop of the production line. Resin deposition which is a oxidation problem, can only be mastered by removing the micro mass to a particle size < 0,1 micron. And even lower.
Oxidation speed coincides with the square of the particle surface area. and
Oil + micro mass = Abrasive paste
So I repeat; As a customer you should demand better filtersystems and cleaner oils when buying.

To arie mol
That asks how NAS class 6 be maintained during operation if the oil filter is 10 micron, taking into account that during operational life internal wear will produce particles smaller than 10 microns. The answer is no, it can't. New hydraulic oil achieve about 2-4 millions of particles/l. These particles will be crushed down during use and will increase. Se above.

David Cummings

Oil Health has be come a much more holistic approach much like medicine. Buy testing the following:

 Assess the basic health of the lubricant and turbine system (IP Package)
 Determine the Varnish Potential of the lubricant (QSA)
 Look at potential degradation mechanisms in the oil (FTIR)
 Identify changes in turbine oil formulation or the presence of incorrect lubricants (FTIR, RULER)
 Calculate the antioxidant health of the lubricant (RULER)
 Determine if the fluid is susceptible to auto-degradation (FTIR, RULER, QSA)

This will show the health of the oil and how dirty the oil is. Keep in mind the two are different. As Matt said "The oxidizing of the oil is a mechanical + chemical process witch is continually going on. This process is dependent of oxygen but also of how much energy that is added while operating." The chemical make up of the oil is the health of the oil. If the oil is healthy, additive pack still within 50% of new, you are testing the oil on a regular basis to trend QSA and ISO numbers and additive pack health (especially anti oxidants levels) and use an active filtration system your oil could last a very long time. We have a customer with 5 steam turbines that has not changed their oil in 8 years the oil is within 90% of original additive pack and has eliminated oil related shut downs on their turbines.

Get healthy oil, Filter it with an active system (electrostatic) and trend the indicators with good testing. With an electrostatic filtration system the ISO codes will always stay within spec. Please contact me with any questions dcummings@isopur.com