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Why Flow Coat Paint Beats Other Types of Transformer Repainting


A transformer is a crucial electric device that transforms electric energy from one circuit to another without any change to the frequency. It is done by the mechanism of electromagnetism, and for the process to happen smoothly, it is extremely important that the body of the transformer is well-maintained.

With modern society relying more than ever on uninterrupted power systems, the demand for transformers is consistently high for a good portion of the several last decades. It provides a reliable power supply, often controlled by a utility or a power company that ensures the transmission is smooth, and that everyone is getting their fair share.

For obvious reasons, electric transformers are expensive assets for utility or power companies, and they spend quite a lot of money every year for their maintenance and upkeep. Even if customer demands force an installation of a larger and powerful transformer at a location, the companies usually put the older one at another location i.e., reuse it to save cost. Not to mention that transformer downtimes and service interruptions tend to be more expensive for the companies.

For transformers to work better, regularly scheduled maintenance check-ups are important.

Transformer Coatings

Even though the chassis and other physical components that make up the electric transformers are built to last for many decades – even 50 years -- the outer coating of the system is often not done to build to last.

Outer paint coating also plays a crucial part in maintaining the system working effortlessly. There are many environmental factors that escalate the paint erosion including moisture and rust, to name a few. Transformers with deteriorating paint risk severe corrosion developing which can result in leaks and subsequent tripping out of electricity. Out of all the components, cooling radiators are the most sensitive, and hence even a little damage due to faulty coating can cause long-term problems.

When planning on transformer repainting, a good portion of the budget goes to the surface conditioning. It includes cleaning the surface as well. The worst the shape of the transformer is, the more effort you need to make it paint-ready.

For the companies to schedule transformers repaint, they must check the condition of the transformers. It is better to call for a paint job before the corrosion has set in, as it increases the costs.

What is Flow Coat Paint?

Flow coat paint is used in paint jobs that involve spraying a surface with paint in large amounts. The whole system design manages to collect the drip-off paint and automatically induct it back to the spraying component. With this method, there is almost no loss, and its performance is 90% better than any other painting method.

Since painting transformers is a job that requires extreme precision, professionals take care of flow coat coverage that it is done evenly. The coat can flow freely over the entire surface, and it leaves a thin layer of the film once it dries. To get this thin layer, professionals usually use a low viscosity liquid paint. Some surfactant substances such as sodium stearate, docusate, and alkyl ether phosphates are used to make the flow well-ordered.

Flow coating process is usually done vertically to take advantage of gravity so the paint streams that run off the surface fall into a collection system. It increases the flowchart coverage as well, leading to this method being the preferred choice of many companies. Another common term used for this method of painting is “curtain coating.”

Spray Paint vs. Flow Coat Paint

The two main choices while painting transformers are spray paints and flow coats. The significant difference between spray painting and flow coating is the flowchart coverage percentage. Spray painting is cheaper than flow coating, but it does not last long and does not have adequate corrosion-resistant properties like flow coat does.

Applications of Flow Coat Paint

Flow coat painting is done on various surfaces and objects manufactured and assembled in a factory. Electricity companies use flow coat paint for transformer coating because of its flow coat coverage. It provides a 100% flow coat coverage of radiator surface area, including backsides and other restricted surfaces, e.g., fins, tubes, stabilizer bars, etc. It also completely covers the joints, seams, and crevices of radiator banks that are difficult to access because of the built of the system.

Another common application of flow coat paint is that it is used as a rust-resistant coating. It is mainly done while transformer repainting is done to strengthen the body of a transformer against rust. The rust prevention works like a barrier using chemicals that neutralize rust and its causing likelihood by trapping the corrosion and weather-induced erosion underneath subtle coating layers.

For transformers that immediately need paint rework to include those which have paint blistered, flaking, or peeling. It is especially important for places where you cannot usually reach due to the structure of the electric device. Problems like these are also furnished with chemical surface treatments that include soluble salts such as chlorides, sulfates, and nitrates. These are applied to bare metal surfaces to provide a coating replacement that is corrosion free for a significant amount of time. These salts are great against moisture damage as well.

Why Is Flow Coat-Painting Better?

When it comes to the question of why flow coat paint is better than any other transformer paint, there a number of reasons. Some of the prominent ones are listed as follows:

  • 100% flow coat coverage: We know that flow coat coverage is 100% on transformer surfaces, but it is most widely used because you do not need to disassemble the whole system and paint them individually. It is one of the biggest reasons many electric utilities prefer getting flow coat painting for their transformers

  • Causes no service disruption: Because you do not need to separate transformer parts to paint them using flow coat paint, there is no effect on the performance during transformers repaint or paint for the first time

  • Weather-resistant: Unlike many paint jobs, flow paints tend to stick longer and provide better weather-related damages, e.g., from moisture, rust, etc. If you choose simple spray paint, you will have to treat rust separately, which costs more than flow coat paint job

  • Cleaning: Another advantage of flow coating is that the coating itself removes any dirt or dust particles on the surface of the transformer

  • Coating material usage: With this method, a very little amount of coating material is actually required because any excess paint falls and is reused, making it a very effective painting method because it costs less and has recyclable properties

  • Miscellaneous: The coating provides some other performance benefits including protection against UV radiation, chemical irritants, scratch and abrasion resistance of the finest international standards

Equipment Used to Flow Coat

The equipment required for flow coat painting is straightforward. It would help if you had a motor-driven pump of 10 to 20 GPM capacity with a by-pass valve to regulate the flow of paint. You would also need a 3/4 -inch hose, a few 3/4 -inch pipe fittings, and some metal catch pans for catching the dripping paint.

The paint which is most widely used is oil-based that is prepared specifically for flow coating. Some companies also recommend using relatively modern paint that uses a water-based polymer and needs a two-coat system to dry. It dries faster, even at 6 degrees Celsius, making it cost-effective. The smaller number of coat application is another cost reduction benefit. Some professionals also recommend using an alkyd paint with a three-coat application.

Surveys Leading to Flow Coat Paint

Before coating transformers, the specifications of the coating system are essential to assess. The professionals assess any damage to the original coating before proceeding any further. Much of the damage to the outer layer of the body of the transformer is caused by bad handling of the product, probably during shipment. The environmental situations are also checked to see what kind of finish coatings should be done to make the coating last longer. Some companies send their teams on routine surveys every two years to check the situation of the transformers. If the damage is minimal, often a water-based epoxy is used to plaster over the damager spots to hold the coating a little longer until the whole unit is refurbished.

How to Flow Coat

The necessary process of flow coating is to paint the transformer includes specific steps. You have to clean the panel thoroughly and then allow it to reset. You also need to sand it and apply a clear base on the surface; it is better to use two or even three layers. After that, you can go ahead and paint the transformer body.

These are explained in detail as follows:


The first step of any transformers repaint is to clean the outer surface. You have to make sure that the outer surface is free from any chalk, oil, or dirt. Also, check for loose paint. Some companies also use pressure washers and grinders to get down to bare metal on points where the paint cannot stand longer. You can also use soluble salts for cleaning that includes chlorides, sulfates, and nitrates for any invisible residues and impurities.

Transformer Protection

Transformer protection includes wrapping and masking the insulators, gauges, and other sensitive equipment to avoid spraying over to them and damaging them as a result. The heavily rusted areas are treated with epoxy pre-prime that acts as an anti-corrosion agent.

Flow Coating

This process is painting the radiators uniformly with a single coating. You should erect a containment system surrounding the radiator bank before starting anything. This system will help you with the paint regulation as it reuses the dripping streams as they collect at a collection reservoir at the bottom of the system. You can use mineral spirits to thin primers. It makes the paint less dense and allows maximum flow coat coverage.

Another essential point to remember here is that a lot of damage to the radiators is caused by improper paint job, and it is another reason to choose flow coating over any other painting system to minimize that damage.


A primer coat guarantees long-lasting results and provides a firm bonding surface to the finished flow coat coverage surface. This is a very vital step if you want to get excellent results that can sustain the test of time and weather. The most widely used primers include zinc phosphate.

Finish Coating

You can apply some poly-silicone topcoat to strengthen the skin further. The gloss of this coating is not only aesthetic but also provides protection from excessive heat as it cools the temperature while the transformer is in use.


In the end, you have to remove the tape and protective covering over insulators and other components, clean the area around your workstation and replace the fans and signs to give a fresh and clean look. You can also reassemble any substation structures and transmission towers of hot-dip galvanized steel. Galvanizing makes the components last for up to half a century, so it may be a smart choice for you if you wish to invest a little further in the maintenance. It would help if you also boxed away from any equipment you used during the painting process.

After the paint, your transformer will look bright and brand new, as well as ready to work smoothly for a good number of years.

When Should Transformers Repaint Be Done?

Ideally, the utility servicing transformers should not wait for the corrosion to take over, or wait to see when the paint wears off. Transformers repaint should be done every five years in heavily polluted locales. It also includes areas that are closer to coasts and the marine environment. For areas that are medium polluted or are more comparable to industrial estates, it is better to re-coat every ten years or so.


The most common method of repainting transformers also happens to be the greatest in terms of flow coat coverage, its benefits for the overall performance of the system, and longevity. The amount of layering done for the process is usually more than twice to make the paint stick for a longer period. Modern methods also use electric flow coating nozzles that supercharge the paint particles. This method is mostly used in automobile production and finishing.

If you want to know more about transformers repainting and how it is effectively done on any such device, you can feel free to visit for a better understanding of how the painting procedure is done by professionals.

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