Painting a hot water tank: how the work can be done, pre-treatment

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Published: 04/22/2020

Reading time: 4 min

1 Material requirements
2 What can you paint with?
3 Painting process
4 Pre-treatment
5 Features of applying the material
6 Need for air circulation
7 Time to put products into operation
8 Advantages of the AntikorBEP-M material

Ethyl silicate with zinc powder

They are made from two parts: a base of ethyl silicate and zinc powder. Which are mixed before directly painting the product.

After 24 hours have passed, you can start using hot water from the tank without fear that the coating may be damaged.

It is very important to remember that all work on preparing the tank for painting must be completed 6 hours before painting is carried out. To ensure excellent grip, it is better to work at temperatures from -15 to +40 degrees.

Product commissioning time

After what period of time can a freshly painted tank or container be used?

This question is asked by many customers who buy the material. At first glance, the answer to this seems obvious, but upon a more detailed study of the issue, everything turns out to be not so simple... As specialists who have been involved in the development and production of anti-corrosion materials for a long time, we want to draw the attention of clients to the fact that the flow of physical and chemical processes inside the coating does not end upon reaching the so-called degree 3.

Customers often mistake a partially dried surface for a fully formed and ready-to-use coating. This is a grave mistake! Commissioning (filling with water) of containers protected with KO-42 is possible no earlier than 6 days after the last layer has dried. However, this value is indicative, since it depends on the air temperature, humidity, air exchange rate, etc.

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Cetra

This is not a capricious paint, which has a high level of resistance to moisture and temperatures, and can withstand high temperatures in the tank for about 7 years.

This paint substance is used in oil and gas processing plants for painting the inside of special containers.

In addition, such a coating is not afraid of moisture and high temperature, but does not yet react to various chemicals. If you take this paint to cover the inner surface of a tank in a bathhouse, it will be an excellent option for protection against rust.

Traditional technologies for combating corrosion in sauna tanks

In private homes, gardens and summer cottages, almost every owner has a bathhouse. Before the invention of two-component enamels, anti-corrosion, and high-quality paints and varnishes, three technologies were used:

Aluminum powder - diluted with liquid glass, withstands extreme temperatures of 700˚C, does not change water quality, is considered environmentally safe
Lime/cement solution - the components are mixed to a creamy state of 1/1, after which the tank is coated, the inner surface is dried either with wood chips (those that have absorbed moisture are removed, the tank is filled with a new portion), or with the heat of a hairdryer
Red lead - present on the shelves of most stores, is a filler for weather-resistant paints (a mixture of powder with pentaphthalic varnish)

Modern coatings for corrosion protection

There are several groups of products that reliably protect periodically heating/cooling water vessels from rust. For example, CVES No. 2 is a two-pack anti-corrosion agent based on episilicate and zinc powder. In the field, the product is applied to rust-free surfaces with a brush or roller. When making the mixture, the B-component is constantly added to the container with the A-component.

After some aging, it is enough to strain the mixture to begin work. In winter, the product to be painted must be heated to a temperature of “dew point + 3˚C”. Indoors, surface preparation should occur no earlier than six hours before painting begins. Recommended temperature range for corrosion protection is +40˚С – -15˚С. Humidity above 80% and below 30% is not recommended.

Heat-resistant Certa is created for extreme operating conditions and is used in petrochemicals, hydraulic and thermal structures. She is not afraid of superheated steam with periodic or constant contact. Chimneys, stoves, boilers are painted with this paint in one or two layers. Mineral oils, petroleum products, and saline solutions do not affect the protective film obtained after painting. The coating life exceeds 7 years (for baths); in atmospheric conditions it doubles.

Lead dyes containing iron

There are a large number of such paint materials on the market that reliably protect against moisture and corrosion.

Most of these materials tolerate temperatures up to 300 degrees. Before buying such a dye, you must read the instructions.

Any of the red lead preparations are excellent for painting hot water tanks.

A mixture of cement and lime

Parts of such a mixture are taken 1:1. The result is a consistency that is diluted with more water, and then this material in the form of porridge is applied to the inside of the wall, then allowed to dry. And this procedure is carried out about 7 times.

The protective functions of this composition are not very good, so today this mixture is almost never used.

Preparatory work

Just painting the inside is not enough. It must be prepared in advance; if this is not done, then the entire painting job will be ruined (as soon as the water heats up, the coating will immediately begin to peel off, and the water will become very dirty and unusable).

Therefore, to avoid this, it is recommended to carry out the following work on the inside of the tank:

Clean off rust, dirt and scale well;
Go through with degreaser;
Apply anti-corrosion material if there is rust;
Apply a primer if necessary (a large number of rust protection materials are also primed at the same time).

Features of material application

After drying, KO-42 forms a uniform, rough, gray coating. Material consumption is about 250-330 g/m2. When using a hand-held painting tool, these values increase; when using an air or airless application method, they decrease accordingly. To obtain the estimated service life, paint is applied to the metal in 4 layers. In this case, the thickness of one layer should not exceed (30-40 microns).

ATTENTION: We strongly do not recommend changing the thickness and number of layers. Otherwise, cracks and other defects may form on the resulting coating.

One of the advantages of this composition can be considered the fact that the properties of the product allow the painting of structures in sub-zero temperatures - the minimum temperature for applying the material is minus 10 ° C. In this way, metal structures can be protected from corrosion not only in summer, but also in winter or in the off-season.

One of the features of cold galvanizing compositions is quite high requirements for the quality (cleaning) of the metal surface of the product being painted. Thus, to obtain a durable coating that retains the properties declared by the manufacturer throughout the specified service life, it is extremely important to ensure the required level of metal cleaning. So, before applying the composition you should:

Clean metal surfaces from traces of corrosion and any other contaminants that reduce adhesion (blast or mechanical cleaning to Sa2, Sa2½ or St3)
Carry out metal degreasing work
Remove the old protective coating (sometimes you can apply the composition to the old coating, provided there is sufficient adhesion of the material to the base)

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Particular attention should be paid to the issue of mixing the components of the KO-42 composition with each other. So, the first condition that must be met is the temperature of the components. The temperature of the ethyl silicate base, as well as the zinc itself, should be from 15°C to 30°C. It is better to use mechanical mixers for mixing. In this case, a hand tool is unlikely to be able to ensure uniform mixing of the base with zinc.

There are many subtleties. At the same time, even experienced painters cannot always achieve the required quality.

Cleansing

It is better to clean the inside of the container where hot water is stored by hand. To do this you need to have:

A wire brush with stiff bristles;
Metal grinding machine.

Scale, sediment, and corrosion are removed from the metal surface. After this cleaning has been done, the tank is washed with the product and then rinsed with plain water.

If the tank is new and you want to paint its inner surface simply to prevent rust, then it will be enough to wash and rinse it with plain water. Next, take rags and wipe the tank so that the walls are completely dry.

How to degrease

Even if you very carefully carry out the procedure for cleaning the inside of the hot water tank, there is a possibility that some greasy stains remain, which usually spoil the process of adhesion of the products to the surface, and the painting will not be of high quality.

Therefore, after washing, it is imperative to degrease the surface; for this use:

Solutions that contain alcohol. They do not leave a smell after drying completely.
Gasoline and other solvents. Such compositions work well with grease, but the water will have an unpleasant odor the first time you use the tank.

Such compositions are applied to the surface and left until the base for hot liquids is completely dry.

Treating the base with anti-rust agents

If there is rust, then you can at least stop its spread, and anti-corrosion agents will help with this.

When you buy such a drug, you need to look at how it affects rust, as well as how this drug is combined with the paint that will then cover the tank.

For such work they usually buy:

Insulators are such compounds that form a film on the surface through which water does not penetrate. Insulating agents are based on lead white and therefore are excellent for lead paints.
Passivating - they slow down the spread of corrosion. They can be used in conjunction with epoxies and paints. Very often, epoxy products have broad characteristics and can immediately protect the base, act as a primer and paint, so they are applied immediately after degreasing.
Protectors - they contain small grains of metal, so after complete drying, a thin film of metal is obtained. This product is used when the finishing coating is a preparation of glass and aluminum powder.
Products with orthophosphoric acid. Thanks to the presence of such acid, it is possible to avoid the appearance of rust, and it is also possible to “repair” areas with rust, if any. This acid turns rust into iron phosphate (and it is not at all afraid of chemical compounds). It is recommended to use such compositions if the rust is very old and deep, and the walls of the tank are thin.
Based on silicic acid - such compositions are usually taken from a car shop if it is necessary to paint the inside of the tank. This material is diluted with water 1:3 and left in the container for 12 hours, then the tank is washed well and allowed to dry completely. In this way, it will be possible to eliminate chemical conflict with the finishing layer almost 100%.

Painting process

Paint KO-42 is a complete composition intended for cold galvanizing of the internal surfaces of metal containers with drinking water. The intended location of operation, as well as the location and size of the tanks, do not matter in this case.

Thus, it can be used to paint containers placed on ships, mobile tankers and stationary tanks. The composition is two-component, so before application it requires mandatory mixing of the ethyl silicate base and zinc powder.

The paint has high protective characteristics - 4 layers of material applied to a previously prepared metal surface in contact with water retain their properties for 3-4 years. Material KO-42, which acts as a coating for water tanks, is an environmentally friendly product.

To paint the inner walls of a vessel, it is impossible to use the so commonly used and economical roller or spray gun; only a brush can be used. For work it is recommended to purchase:

wide paint brush for painting walls;
a small brush to paint seams and joints.

You can paint the inside of the tank in the same way as other metal surfaces:

Using a wide paint brush, apply a layer of paint onto large substrates without drips or streaks.
Weld seams and corners are carefully painted with a small brush.
The product is left to dry completely for several hours (drying time is indicated on the packaging of the product used).
After the first layer has dried, re-painting is carried out following the same steps.

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The instructions for most coloring compositions state that one coat of paint is enough to provide reliable protection, but experienced craftsmen recommend applying another one. This is based on the fact that beginners can make mistakes in their work, for example, unevenly distributing the composition over the surface, poorly painting individual areas. In any case, applying an additional layer will take a little time and money, but the quality of the work will significantly increase.

After painting with paints and varnishes that prevent the development of corrosion, a sauna heating tank will last much longer. The main thing is to use the selected product in accordance with the attached instructions and carefully follow all stages of preliminary preparation of the product for painting.