Electrochemical Weld Cleaning - The Fastest and Safest Way to Clean Stainless Steel Welds
Electrochemical weld cleaning is a process by which post-weld impurities such as rust, heat tints, and discoloration are removed from metal surfaces under the effect of mild electrolytic fluids and a weak electrical current.
But what makes weld cleaning a necessity?
Is electrochemical weld cleaning effective and how effective is it actually?
How does this technique compare with other weld cleaning methods?
To learn more about these and other points related to electrochemical weld cleaning, please continue reading below.
Why is Weld Cleaning Necessary?
Weld cleaning is done to increase the corrosion resistance of metal surfaces after TIG and MIG welding.
Metal surfaces and welds are quite susceptible to different types of degradation – Rust and cross-contamination are just some of the examples.
Problems such as discoloration and heat tints often occur after certain welding techniques are applied.
Both sets of problems can be eliminated through proper cleaning and finishing.
What Causes Corrosion?
Preparation of metal surfaces for welding leaves them exposed to different atmospheric elements like oxygen and humidity which creates perfect conditions for rusting.
This is why weld cleaning (and polishing) is crucial for the preservation of strength, shape and other properties of steel structures. Increased durability and attractive appearance of metal surfaces are additional benefits of the cleaning process.
Types of Weld Cleaning
MECHANICAL WELD CLEANING
Mechanical weld cleaning includes use of grinding machines and abrasives to remove the upper layer from the metal surface where rust and other imperfections are formed. This process is time-consuming and rarely achieves clean results with necessary aesthetic value.
CHEMICAL WELD CLEANING
Pickling paste is the most commonly used chemical for weld cleaning. The process is fairly effective but is increasingly unpopular due to obvious shortcomings:
Health hazard - Pickling paste contains hydrofluoric, nitric and sulfur acids. All of them are highly dangerous for the human body and can cause serious and long-term damage to the skin and internal organs.
Ease of use - Pickling paste can be used only by certified operators. In addition, the entire body has to be covered so no contact with the acid occurs. This adds a whole new level of complexity to your weld cleaning process.
Environmental impact - Immediate damage to the human organism is not the only negative side effect of using the pickling paste. Air pollution and waste materials pose a serious threat to the environment.
Read more about the dangers of the pickling paste here.
ELECTROCHEMICAL WELD CLEANING
Electrochemical weld cleaning is faster and more effective than the other two methods. Also, it does not pose significant danger to human health.
This method is exceptionally effective with removal of cross-contamination, rust and other forms of impurity on metal surfaces.
Electrolytic Weld Cleaning Process
The electrolytic cleaning process is extremely simple.
A mild electrolytic cleaning fluid is applied to the surface of the weld by using a conductive weld cleaning brush. Electric current (AC/DC) is employed so desired cleaning and passivation results are accomplished.
Here is a nice demonstration of the electrochemical cleaning process:
Understanding the difference between manual electrochemical cleaning and electrolytic baths
The process described above refers to the manual application of electrolytic liquids to the workpiece using a carbon brush.
However, the electrochemical method also involves another approach, which is the use of special electrolytic baths (not to be confused with chemical pickling baths).
Instead of using a brush, the metal parts are immersed in electrolytic fluid where a chemical reaction occurs to remove rust and other contaminants from the surface.
Although very similar in principle, there are several significant differences between the two techniques that should definitely be considered.
- Work flexibility
Thanks to the easily portable equipment, manual electrochemical weld cleaning can be done on- and off-site. Contrary to this, electrolytic baths are constructed and kept within designated production areas.
- Surface treatment
When you submerge metal parts in electrolytic fluid, there is no choice but to affect the entire surface. Manual weld cleaning is most often done locally (weld area and the Heat-Affected Zone). This is a much more delicate and precise approach that gives greater control over how electrolytes affect the surface.
When it comes to manual weld cleaning, the initial investment in equipment and the cost of consumables are kept to a minimum. With electrolytic baths, the associated costs (construction, maintenance, and operation) are much more pronounced.
Below we list several other distinguished benefits of manual electrochemical weld cleaning.
Benefits of Electrochemical Weld Cleaning
Here are the main benefits of weld cleaning with electrochemical machines:
Flexibility - Electrochemical cleaning systems are portable and you can easily use them on-site – you are not confined to a controlled area.
Safety - Electrolytic fluids only contain a mild phosphoric acid (also used in soft drinks) and can be used by both hobbyists and professionals. Protective equipment (gloves excluded) is unnecessary in most cases.
Process speed - Electrochemical weld cleaning is extremely fast. Good machines will clean and passivate the surface at the same time – no unnecessary hassle and repetitions.
Optimal corrosion resistance – Our research suggests that the electrochemical process provides the best corrosion resistance compared to other cleaning methods.
Electrochemical weld cleaning is especially effective with stainless steel welds.
Why is this important? - Stainless steel is widely used in all industry branches due to its appearance, durability, maintainability and high corrosion resistance.
Electrochemical Weld Cleaning vs Electropolishing
Although essentially similar, electrolytic weld cleaning and polishing differ significantly in how they affect the surface.
Specifically, weld cleaning removes surface contamination without altering the surface itself.
On the other hand, polishing removes a microscopic layer of the surface and, consequently, also removes surface contamination.
Naturally, the primary goal of electropolishing is to reduce surface roughness and improve the aesthetic appearance of steel.
If you want to know more about electropolishing, read our comprehensive article here.
Surface (re)passivation and its Role in the Electrochemical Weld Cleaning Process
When compared to other steel alloys, stainless steel is unique in its ability to fight corrosion and preserve its structural integrity.
However, it is still far from being completely rust-resistant.
Here is why.
Thanks to its specific structural composition, stainless steel is equipped with a passive surface layer that stops oxygen particles and moisture from reaching its iron base.
This protective surface film is often heavily damaged during different types of fabrication (e.g. welding) and is then no longer capable of inhibiting corrosion.
After losing its passivity, stainless steel will naturally fall prey to rusting and – sooner or later – succumb to corrosion-induced decay.
But all is not lost.
The good news is that the passive protective layer can be completely rebuilt.
This process is called (re)passivation.
When utilizing the electrochemical method, surface passivation is conducted simultaneously with weld cleaning, which means that you will effectively finish both processes in one pass.
You will be able to successfully remove different types of weld contamination (heat tints, discoloration) and protect the surface from future corrosion - all this at the same time.
It really is that simple.
This is actually one of the greatest advantages of the electrochemical method over other weld cleaning techniques.
Mechanical grinding and chemical pickling can provide decent results, but unlike electrochemical weld cleaning, these methods do not guarantee re-passivation, which is a huge disadvantage when it comes to stainless steel.
If you want to know more about the benefits of proper passivation, we recommend reading our detailed article on the subject:
READ MORE: Passivation of stainless steel after welding
Are Stainless Steel Welds and Surfaces Easy to Clean (and Passivate)?
The material is exceptionally resistant to corrosion. Under normal conditions, it will easily maintain its appearance and integrity – kitchen sinks are an excellent example.
However, the industrial environment is rather harsh so it is extremely hard to avoid rust – particularly in the area of the weld.
Majority of common defects appearing on stainless steel welds – rust, discoloration, heat tints, weld and burn marks – can be easily and successfully removed through basic electrolytic treatment.
Electrolyte fluids can penetrate even the smallest cracks on the surface of metals and prevent further problems like pitting and corrosion build-up.
Electrochemical cleaning does not change the metal surface - it only returns it to its original (bright and shiny) condition.
Maintaining the attractive appearance of stainless steel is an important aspect of electrochemical weld cleaning.
So, are stainless steel welds easy to clean? – The answer is yes, but...
You need to make sure you use the right equipment (machines, accessories, and consumables) for the job.
Our Recommendations for Stainless Steel Weld Cleaning
Cougartron’s proprietary weld cleaning systems have been developed to answer the rising demand for fast and safe stainless steel cleaning solutions.
Weld cleaning machines for stainless steel
Weld cleaning machines from Cougartron are compact and lightweight but strong enough to remove all imperfections on stainless steel after welding.
InoxFURY is the most powerful electrolytic weld cleaner currently available on the market. It is built to withstand heavy-duty use on larger stainless steel and aluminum welds and surfaces. Suitable for all weld types.
ProPlus is a superior solution for cleaning MIG and TIG stainless steel welds. The system weighs only 15 kilos and can be used off- and on-site. Use Cougartron ProPlus to clean up to 60m of welds per hour.
Cougartron Plus is lighter and less-powered than ProPlus but still highly effective on stainless steel TIG welds.
The machine is ideal for on-site use and smaller production environments.
InoxMuscle has the highest power-to-weight ratio in the market.
The machine weighs only 3.7 kilos but does wonders with weld cleaning and electro-polishing. This is a flexible and mobile solution for stainless steel TIG welds.
InoxPower is an affordable entry-level weld cleaner for occasional use on smaller stainless steel welds. It lacks the electropolishing functionality but still provides amazing results with weld cleaning and surface passivation.
Weld cleaning fluids – electrolytes
Electrolytes are liquid chemical compounds used to protect the steel surface against formation of oxidized stains and rust.
Here are some of our major liquid solutions for stainless steel:
Cougartron CGT-550 Weld cleaning and polishing fluid
When used with Cougartron weld cleaners, CGT-550 achieves impeccable results on stainless steel welds. The liquid can be used for weld cleaning, passivation and polishing.
Cougartron CGT-350 Weld cleaning fluid
CGT-350 is a milder version of CGT-550 and gives great cleaning results with both TIG and MIG welds.
Cougartron CGT-N1 neutralizing fluid
Neutralizing fluids are applied after weld cleaning to ensure that no acid residues are left on the weld surface. CGT-N1 is especially effective with white acid marks.
Cougartron CGT-N5 neutralizing fluid
CGT-N5 is our new neutralizing fluid for brushed steel surfaces. It effectively removes acid residue from steel grooves.
Weld cleaning brushes
Importance of using quality brushes when weld cleaning cannot be emphasized enough. Hair thickness and fiber structure are just some of the elements to consider. We offer different brush types for different applications – below you can see some of the models:
Powerbrush has a particularly strong fiber structure which is ideal for the most demanding weld cleaning operations. The brush is also highly durable and resistant to heat – it will last longer and do more!
Superbrush with hex crimp
Superbrush is a thick and dense weld cleaning brush for heavily-oxidized stainless steel welds and surfaces. Best used with Cougartron ProPlus and InoxFURY.
Specially designed brush for InoxFURY, used in combination with the triple brush adaptor to provide effective weld cleaning results on larger steel surfaces and welds.
Thunderbrush is a thick and flat weld cleaning brush with a dense fiber structure. Thanks to its design, the brush provides effective weld cleaning results without being moved in different directions.
Pipebrush PRO weld cleaning brush
It is quite challenging to clean interior welds on tubes and pipes – if you are not using the Pipebrush PRO. This brush was designed to thoroughly clean hard-to-reach surfaces and welds within stainless steel pipes.
Weld cleaning is a key post-welding process used to prevent corrosion on metal surfaces.
Three weld cleaning methods are distinguished:
- Mechanical (grinding with abrasives)
- Chemical (pickling paste treatment)
- Electrochemical (Cleaning with electrolytic fluids)
Mechanical process is fairly ineffective and time-consuming. Pickling is more effective but poses a dangerous threat to human health.
Electrochemical cleaning is a safe and fast alternative to these methods. It also provides better protection against corrosion and rust.
The method is particularly effective when applied to stainless steel welds. Rust and other impurities are quickly removed and/or prevented.
However, this cannot be achieved without proper equipment.
Cougartron has developed a line of compact and strong weld cleaners designed to provide unrivaled cleaning performance and optimal results on stainless steel welds.
Get a free consultation
If you need help with your production or a specific weld cleaning project, please contact us for a free consultation at any time.
Weld Cleaning Q&A
When you start to see excessive arcing at the tip of the brush, it’s time to dip again. When there is not enough fluid in the brush, weld-cleaning performance will be reduced, and the brush will start to burn away.
It is a manual process and a visible decision. It is important to understand that the machine does not easily remove slag or oxides but the passivation will still be complete.