Before passivation or any other precision-cleaning process, all system hardware must undergo degreasing.
If you’re wondering what degreasing is and why it’s necessary, we’ve got you covered. In this article, we take a deep dive into degreasing, the different types of degreasers (including solvents and aqueous-based cleaners), and when and why we use this process at Precision Fabricating & Cleaning (PFC).
- Degreasing is a crucial process that removes dirt, grit, scale, corrosion, grease, oil, and other foreign matter from system hardware parts before undergoing any precision-cleaning process like passivation.
- There are different types of degreasers available, including solvents and aqueous-based cleaners. Solvent degreasers are used to remove organic contamination, while aqueous-based degreasers are used to remove both organic and inorganic contamination.
- Degreasing is essential before passivation, as it ensures the removal of all excess grease, oil, lubricants, and other contaminants from the surface of the system hardware beforehand, which is necessary for the passivation process to succeed.
- There are different methods of degreasing, including vapor, immersion, steam, high-pressure water jet, and ultrasonic cleaner, among others. The degreasing process involves an initial cleaning to remove gross contamination, followed by degreasing with alkaline or solvent solutions.
- The choice of cleaning agent depends on the type of part and material, and PFC works together with customers to ensure the best degreasers are used for the job.
Degreasing is a process in which system hardware parts are cleaned to remove dirt, grit, scale, corrosion, grease, oil, and other foreign matter.
Depending on the type of part, the type of debris and its level of thickness, a variety of degreasing methods may be used. They include:
- Immersion in, spraying or swabbing with alkaline or emulsion cleaners
- High-pressure water jet
The parts may also be submerged in an ultrasonic cleaner, a machine that helps remove stubborn contaminants using high frequency sound waves.
System hardware is always degreased before undergoing a precision cleaning process like passivation. This way, the surface of the hardware is cleaned of any debris that would render the next stages ineffective.
Degreasing also removes substances which may be incompatible with the hardware’s intended service media.
Degreasing is especially important for passivation. Without removing all the excess grease, oil, lubricants, and other contaminants from the surface of the system hardware beforehand, the passivation process will fail.
In case you aren’t aware, passivation involves submerging stainless steel hardware in a chemical solution consisting of citric acid or nitric acid. The acid removes all free iron from the surface of the hardware, leaving it with a higher proportion of chromium than the rest of the part. Once the hardware is taken out of the bath and exposed to air, the chromium on the surface binds with the oxygen in the air and forms a layer of chromium oxide. This renders the surface non-reactive as well as resistant to rust.
If there is any lingering debris on the hardware left on it as it goes into the passivation process, the acid will not be able to do its job. For that reason, at PFC, we always subject system hardware to degreasing before passivating them.
Degreasing chemicals fall into two main categories: solvents and aqueous-based.
A solvent is a substance - typically a liquid - that is capable of dissolving or weakening other substances. They are used as degreasers to remove some forms of organic contamination (e.g., oils, grease, and hydrocarbon fuels).
Below is a list of commonly used solvent degreasers.
- Isopropyl Alcohol (IPA)
- Ethyl acetate
- HFE 7100
- Vertrel MCA
- Solstice PF
- Coventry 12830
An aqueous-based solution contains water and is typically milder than a solvent, which is acid-based. Aqueous-based degreasers are mild alkaline cleaners, soaps, and detergents used for the removal of organic and inorganic contamination (e.g. oils, fats, soil, and grease). They still contain chemicals, but at low concentrations. Furthermore, they are heated to improve effectiveness.
Below is a list of chemicals that you’ll typically find in an aqueous-based degreaser.
- Turco 4215 NCLT
- Naval Oxygen Cleaner (NOC)
- Brulin 815GD
- Daraclean 282
- Amway nonionic L.O.C
There are several different methods of degreasing, which we’ll get to in a moment.
But before any of them can begin, an initial cleaning must take place. It involves the removal of gross contamination from the hardware to reduce the amount of contamination that is introduced into the degreasing tanks.
A pressure washer is used to remove gross contamination on large parts with the aid of demineralized (DM) water. Small parts are cleaned using a smaller pressure washer and alkaline cleaners and detergents.
It’s important to note that all cleaning agents are determined by PFC and the customer. Different parts and materials require special cleaning solutions, and we always work together with customers to ensure we use the best degreasers for the job.
After all gross contamination has been removed, it’s time to move on to degreasing. For this process, there are two main methods we typically follow: one for degreasing with an alkaline solution, and one for degreasing with solvents.
- Rack or position parts in a processing basket, so that full contact with process solutions and accessibility with rinse waters will be achieved.
- Completely immerse items/parts in the alkaline degreaser. Where complete immersion is not feasible or immersion method is not effective, apply the degreaser to the items/parts with a swab or soft nylon brush and scrub until the visible contamination is removed.
- Thoroughly flush or rinse parts with DM water until a neutral pH is reached. Ensure all cavities and possible entrapment areas are exposed to the rinse water.
If a part has a fluorocarbon lubricant, then it must be subject to cleaning with a solvent. For this type of degreasing, we will often use an ultrasonic cleaning tank.
Here is a brief overview of the steps involved in this process.
- For hardware which may have fluorocarbon lubricant on it, wipe those areas first with a clean cloth that has been dampened with the solvent. This step will remove the majority of the lubricant from the item/part before it is placed in the ultrasonic tank.
- Place the item/part in the solvent in the ultrasonic tank and run the tank for 60 seconds at ambient temperature.
- Perform visual inspection of the items that have been cleaned to verify that no visual evidence of fluorocarbon lubricant remains. Items that fail visual inspection shall be re-processed until all visible evidence of fluorocarbon lubricant has been removed.
By degreasing system hardware prior to passivation and other precision cleaning processes, we ensure that those processes will be successful. It may seem like an extra step to some, but to PFC, it’s one of the most important steps of all.
Contact us today to learn more about all the steps, expertise, and experience that go into our precision cleaning processes.