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Before we discuss how to remove varnish buildup, it is important to understand what it is and how it occurs. As oil is heated and cooled under normal operations, oxidation in lubricants and additives creates organic by-products. This results in the formation of soft, sticky, polar insoluble particles floating in the oil and a varnish buildup on metal surfaces.
Varnish is most often found in areas of low flow and cool temperatures (tanks and reservoirs) and hot surfaces where oxidation is accelerated. Varnish reduces lubricating oil quality and needs to be removed periodically.
Varnish cannot be removed with mechanical filtration. Side stream or kidney loop filtration processes will need to be setup to treat and prevent varnish, but will not affect normal operations. Current varnish buildup may require chemical cleaning and system flush, but there are ways to prevent buildup from occurring in the first place.
There are three technologies that remove insoluble varnish precursors from oil:
Additionally, there is a new technology available to target soluble varnish precursors.
Charge Bonding, or ICB, targets soluble varnish precursors and works quickly within a few days. One drawback is that because it targets polar oil components this method can also remove polar additives like rust inhibitors. Currently, this technology is mainly focused on gas turbines which have low water content.
Varnish deposits remain an issue. However, as these technologies continue to improve and new ones are developed, varnish removal processes will continue to become more effective. If you are looking for an experienced varnish removal partner or chemical cleaning services, please don’t hesitate to reach out to one of our certified technicians to discuss your project today.
Brett, Caleb. “The Outsourcing Laboratory” www.intertek-cb.com, 2003.
Hetherington, Paul. “Round Table: Off-Site Labs, Industry Professionals Voice Their Opinions about Off-Site OIl Analysis” Machinery Lubrication. Machinery Lubrication, 1 January 2003. Web.
Clark, Randy. (May 1, 2003). Email Interview.
Hydraulic fluid is the lifeblood of your system, keeping everything lubricated and ensuring smooth machinery operation. It’s critical to regularly test your fluid to ensure contaminate levels are below ISO cleanliness levels and lubricant is circulating properly throughout your system. Unmonitored changes to your fluid could produce harmful effects that impact your system performance. But what do you do when your fluid is getting dark?
When Fluid is Too Dark
The first step is to have your fluid lab tested. Tests to uncover specific issues include:
Fluid Test Results Don’t Confirm Anything
If the fluid analysis comes back normal and the acid, viscosity and oxidation come back as stable, that indicates there’s no oxidation present in your hydraulic fluid. The next step is to inspect your valves. If there’s residue on the valves, there’s a possible indicator varnish is precipitating from the fluid.
What is Varnish?
Vanish is the byproduct of lubricant degradation and is generally unstable in oil. As such, it’s prone to form deposits or separate from your bulk oil. Varnish deposits can form on machine surfaces throughout your system, slowing down system performance, limiting valve function and shortening the life of your oil.
The primary cause of varnish is thermal degradation of some sort, which occurs in the absence of oxygen. Thermal degradation is caused by, you guessed it, heat! Typically, there are two broad causes of overheating in a hydraulic systems:
What to Do If You Confirm The Presence of Varnish
To solve the problem before it hurts your system performance, follow these steps.
Have a laboratory provide the FTIR curve of your oil. Don’t have them look at the wave-number region, where oxidation levels are measured. Instead, have them check for a peak in the nitration region. If a peak is present, then you’ve confirmed the presence of thermal degradation.
Investigate the source of heat in your system. Once you know where the heat is coming from, you can determine whether there’s a major system flaw or if it’s possible to engineer a solution that will remove the heat source.
If your heat source is some sort of entrained air, there are engineered solutions to remove bubbles from the hydraulic fluid. If there’s a system design flaw, use a separation technology to remove thermal degradation byproducts from your fluid. This provides a long-term stop-gap solution to the varnish formation until you can implement a system redesign.
More About Reliable Industrial Group
At RIG, we’ve served more than 400 companies nationwide and can help you get to the bottom of system issues with a range of equipment assessments, including:
We offer extensive varnish removal services and also carry a complete line of lubrication system accessories from filters, breathers and suction strainers to fill caps and site gauges.
Pre-cleaning and regular maintenance of piping, critical system components, and lube oil systems are critical to extending the life of equipment and ensuring safe operations. But every minute we spend cleaning means our plants are not operational. Fortunately, innovations in the pre-commissioning and preventive maintenance industries are helping speed cleaning processes up while improving equipment longevity.
Some of these new and improved technologies include:
High-pressure hydrolazing can be used to pre-clean the inside of steam pipes, just before steam blows, clean air-cooled condensers, and more. This allows for a reduced amount of chemical cleaning and zero need to handle hazardous chemical waste.
Some of the benefits of high-pressure hydrolazing internal pipe cleaning services include:
Dry silencers, which come in various sizes and configurations, help with noise reduction during the steam blow process. These silencers allow steam blowing on locations that were previously hindered by location size and available setup space. By reducing temporary piping requirements, dry silencers allow safe steam blows in these tighter worksites.
Modern hydraulic systems run at higher pressures and faster cycle times than ever before, making it harder to maintain fluid integrity under such demanding operating conditions. Glass or synthetic filters help address this problem by providing a better, more reliable contaminate removal method than cellulose filters.
There are several benefits to using Glass/synthetic filters. For example:
This type of varnish removal works quickly and is mainly used on gas turbines, targeting soluble precursors. ICB technology allows for faster cleaning in a less invasive manner than traditional methods.
New technologies continue to be developed, improving equipment longevity and driving better cleaning procedures.
When and why to use steam vs. air blowing is not always easy to tell. Both are good methods and have their use cases. Generally, air blowing is a less stressful method of cleaning than steam blowing, but it doesn’t do quite as thorough a job. Usually, the level of contamination and your target ISO cleanliness will determine which is most appropriate. Let’s dive into specifics though:
Steam blowing, one of the first phases of start-up, uses high-temperature and high-velocity steam to create a high drag force on piping surfaces. This force removes debris, grease and mill scale that forms during the milling, fabrication, and construction of piping and equipment. To remove mill scale the steam must be at a high pressure (usually 300 PSI) and temperature (usually at least 900 degrees Fahrenheit). At lower temperatures, mill scale will stay in place and can eventually break free and contaminate plant equipment during startup. Some best practices include:
There are two types of steam blowing, the puffing method, and the continuous blowing method.
Puffs of steam are injected into your system, beginning at low pressure and slowly escalating to higher pressures, typically about 150 percent of normal operating procedure. It’s performed in stages, across different parts of the system, clearing out debris and mill scale from each area.
The Continuous blowing method uses a similar process, but pressure is maintained continuously during one long blow to reduce force and stress on your system. It puts less stress on your system, but it delivers a slightly lower standard of cleanliness than the puffing method. Depending on the sturdiness and cleanliness requirements of your system, either method can be a good fit.
Air blowing is a similar method in which high-velocity air is pumped throughout your system. In terms of when to use it, air blowing works in great combination with chemical cleaning, such as in power plant systems. The chemical cleaning solution will dissolve mill scale, and then the non-soluble particles that have been dislodged during cleaning can be removed via air blowing. This process puts less direct stress on your system than steam blowing does, so if a chemical clean will be sufficient to remove mill scale, it’s easier on your system to combine it with air blowing.
With over 35 years of experience performing steam and air blowing in plants, we are always happy to help you determine the best methods of cleaning or pre-commissioning your systems.
Steam blowing is critical if you want to ensure piping, boilers, and gas turbines are not contaminated with mill scale, debris and grease before full operation. With proper steam blows, you can protect your turbines and plant equipment from damage upon startup or operation, potentially saving millions in repairs and unplanned downtime. This procedure forces steam through piping at high pressure, to create a drag force that will remove debris. If done improperly, steam blowing runs the risk of overheating sensitive elements, endangering the eardrums of unprepared bystanders and leaving the system unready for operation.
One basic precaution includes using dry silencers that don’t require water injection to reduce noise, which can make a huge difference in risk during the procedure.
When piping is attached to a steam turbine, the turbine OEM has a guideline for steam blowing. There are several methods, referenced in NEMA 23 and NEMA 24 guidelines.
The accepted method for a steam blow, per NEMA 23 and NEMA 24, is an impulse blow, in which you:
Historically, steam blowing has been a noisy, hot, dangerous process.
In the past, steam blows were louder than roaring jet engines. They used an open-ended pipe to vent high-speed steam into the open air, often breaking glass windows in nearby facilities — needless to say, the noise was well above OSHA standards.
In addition, rapid temperature increases and decreases can impair overall system performance, so manufacturers of boiler/heat recovery steam generators have put limits on the rate of temperature variation during steam blows.
The traditional approach to steam blowing is to pump puffs of steam through sections of a system. To reduce sound and temperature dangers, the key here is to use a system of:
In this approach, puffs of steam are blown through the system, beginning at lower pressure and slowly increasing in pressure as necessary, and regulated using quick-opening hydraulic actuated valves.
To control noise, a steam exhauster/silencer is also used. In addition, temporary piping from the temporary steam turbine exit is used with water injection along the temporary pipe, limiting the volume of steam before it reaches the steam exhauster/silencer.
Due to the high pressures of exhaustive steam blows, permanent and temporary systems are subjected to high vibrations and stress. In addition, puffing can take weeks to achieve OEM-specified cleanliness levels.
One way to control noise, limit temperature fluctuations, and speed up the process, is to use the continuous blowing method. In continuous blowing, there’s one continuous, low-pressure blow performed around the clock at a steady temperature and pressure. In this process:
An impulse, or puffing, steam blow requires many valves to close and open to exhaust steam at a good cleaning force, cleaning small sections at a time. But a continuous steam blow is always flowing, so the cleaning force is higher down the line as pressure drops near the exit.
At Energy Services International, we provide comprehensive steam blowing services that:
We’ve served companies nationwide and can help you quickly get your system up to specifications. Contact us to discuss your specific needs.
It can be daunting to try to verify the results of an oil flush. Particles as small as 2 microns can damage your equipment, but the human eye strains to see particles 30-40 microns in width. Besides super human eyesight or giant coke bottle glasses, we have six reliable ways you can personally verify your lube oil cleanliness. You should always use two types of verification; particle counts for microscopic contaminates and inspection media for particles visible to the naked eye.
1. Visual Inspection – While superhuman eyesight is required to see some particles, it is still a good idea to do a visual check. Using a 100-mesh screen (normally required by manufacturers), you can make sure nothing obvious is still running through your system.
2. Patch Kits – For quick checks and people who are okay with knowing they are in the ballpark instead of having a specific and reliable measurement, patch kits offer a fairly reliable and quick solution. Because they do leave room for human error, we recommend always backing up this method with laboratory testing (which can take longer).
3. Independent Lab Analysis – lab results are the most accurate way to know what precisely is happening with your lube oil. We work with an independent lab that returns results in 24 hours or less, but some analysis and labs can take longer. A patch kit for instant verification plus a sample sent off to the lab is always a way to have quick results now and peace of mind later with the certified lab results.
4. Portable Particle Counters – These are fast, reliable and great at identifying microscopic particles. You’ll want a unit that provides ISO and NAS cleanliness code counts. This is still a DYI solution, and false results can easily occur if the wrong type of particle counter is used for your application or you don’t check the calibration before each analysis. Our basic guide for selecting these is:
5.Strainers & Filters – strainers and filters offer tried and true ways to monitor your system for most particles but may miss microscopic contaminates. There are several choices when it comes to strainers, including:
5. Flange Screens (a.k.a. Slip Screens) – These are preferred by oil flush technicians, due to their ease of placement between flanges in gaskets with no disturbance to the piping or machinery. These screens are easily cleaned and reused repeatedly, especially during a flush. The drawback to slip screens is they can become clogged and back up fluid upstream or be destroyed.
Source: Larry B. Jordan
The most delicate moment in a plant project is between fabrication/construction and plant startup. Process systems and other critical equipment must be moved, installed, hooked up to utilities and set up correctly for a smooth startup. But surprisingly, it’s not problems in any of those areas that often cause bad or even failed starts.
Poor or skipped pre-commissioning work can have an extreme impact on the probability that systems will start up smoothly, resulting in significant cost increases and delayed project completion. Why is pre-commissioning so critical?
It’s easy to forget that assembling, welding, moving, installing, and hooking systems up to raw materials and plant utilities all represent opportunities for contaminates, part failures, and other problems to occur. Are you making sure that your piping is truly free of debris? Are you 100% sure that all your instrumentation and controls are working correctly?
Pre-commissioning makes sure all systems are up to ISO cleanliness specifications and functioning properly. The easiest way to ruin brand new equipment is to skip this step and not properly clean systems before startup. Do you want to take the risk a random shop rag got left in the mixing tank, or rust from a process connection hose has infiltrated your brand new piping system? Plan to pre-commission your systems and start your systems or plant off on the right foot.
It can be hard to tell which plant maintenance contractors are a good fit for your needs and trustworthy to hire. Online reviews, websites and experience can be fabricated in a few quick keystrokes, so understanding who you are inviting into your facility can be tricky. Here are a few key actions you can take to make sure you know who are hiring and they know what they are doing:
Ask probing questions – Invite contractor representatives to your facility, and really probe them while they are there. Question any statements or claims the company makes. For example: Question statements that reference the company’s strength’s or competitive advantages. If they claim to have world-class equipment, ask what makes the equipment world class. Find out what they claim as a difference from other vendors? How do they normally structure their projects, timelines, customer service, etc.? Who would you be communicating with throughout the process?
Request testimonials, case studies and other information – You can glean a lot from these materials. For an established, experienced company it should be easy to provide good testimonials and case study examples. Use the materials to try to assess things like:
Talk to past clients – Request a reference list or reach out to others who have used them before and go beyond “Would you this contractor again?” Previous clients are a wealth of detailed information that you want to hear. What went right with the project? What did the contractor’s equipment look like? Did the equipment come in clean and in working order? How did the labor/technicians act during their service? Were they knowledgeable? What would you do differently?
Visit potential contractors and get to know them – With planned maintenance, you sometimes have up to a years advance notice to prepare. Use this time to visit your contractor or potential contractors and get to know them. What is their facility like? Their company culture, safety practices, etc.? How contractors execute safety, cleanliness and training at their facilities will be a direct reflection of how they will act at yours.
Use expert help – If you don’t have an internal expert in the specific services you are looking to hire a contractor for, find a third party expert or request references from your contractor. Put the third party expert in charge of the selection process, or at least heavily involve them in it. Having a neutral third party facilitate execution of the services will keep everyone honest. This should not bother potential contractors worth their salt. In fact, it should actually help them to have someone who speaks the lingo in the room and help set realistic expectations.
Do your due diligence when selecting contractors, but keep in that every turnaround has its unexpected challenges. A good contractor will be open and honest with you, working to solve problems and respond quickly. You and the contractor should have a good working relationship that you both value, which started during this research phase.
Source: Larry B. Jordan