Heat resistant coating for increased efficiency and surface protection
When a substrate is subject to heat and rapid temperature fluctuations, it can lead to surface breakage and corrosion. Electrical and engine components, chimneys and ovens, pipework and chemical plants, all these are exposed to possibly damaging temperatures and conditions. A heat resistant coating works to protect the substrate from variations and extremes of temperature without losing functionality. As well as protecting from heat, these coatings:
- Allow for higher operating temperatures while limiting thermal exposure; increasing efficiency
- Protect from corrosion under insulation (CUI): provide an extra layer of protection between the hot surface and insulation
- Resist temperatures up to 1000°C: Different types of heat resistant coating provide resistance to temperatures from -196°C to 1000°C
- Abrasion resistant: Suitable for rough environments like industrial and offshore
- Reduce thermal fatigue: Heat resistant coating improves performance of machinery and extend component life
In this article we take a look at the different types of heat resistant coating and reveal how to choose the right one for your project. Here you will also find some product suggestions and heat resistant coating suppliers and contractors in South Africa.
Heat resistant paint for various needs
It is important to note that while high temperature coating does provide some protection from flames, it is not a fire resistant coating. Essentially, heat resistant paints can be divided into four types:
1. Sprayed metal coatings
Heat resistance: from -50°C to +550°C
Of all the sprayed metal coatings, thermal spray aluminium (TSA) is the most common as it offers excellent corrosion protection in high temperatures. TSA and other sprayed metal coatings are usually applied on steel to provide protection from corrosion and high temperatures.
Thermal sprayed aluminium is particularly used as high temperature coatings for steel for CUI prevention in onshore and offshore platforms and processing plants.
2. Heat resistant ceramic coatings
Heat resistance: from -196°C to +1000°C
The heat resistance properties of ceramic coating are well known, and some of the highest heat coatings available are ceramics. Ceramic coatings are known among car enthusiasts for manifold and engine component protection, but they also have a reputation as industrial heavy duty and offshore high temperature coating.
The high temperature ceramic coatings are widely used in industrial and offshore applications due to the fact that next to heat resistant they are also resistant to corrosion and a wide range of chemicals.
3. Epoxy and silicone based liquid coatings
Heat resistance: Up to +550°C
The liquid high temperature coatings are usually either epoxy or silicone based. The general rule is that the more silicone the coating contains the higher temperatures it can resist. These coatings exist as single and two component systems and are formulated on water or solvent base.
These coatings can be applied at new constructions, on-site or as maintenance coatings. The liquid coatings have the advantage of being able to be applied even on heated surfaces, meaning fast return to service time.
4. High temperature powder coatings
Heat resistance: From +200°C to +600°C
As well as being corrosion resistant, high temperature powder coatings have been developed for heat resistance to medium to high temperatures. The powders are usually epoxy and silicone-based (like the liquid paints), and silicone-based powders perform better at higher heats.
Powders are becoming more and more popular as heat resistant coating for metal and they can be applied instead of liquid heat resistant coating on ferrous metals (steel) offsite. The reasons why powders may be chosen over liquids include wide colour and finish range as well as zero VOC content.
How to choose a heat resistant coating for metal
As with any coating application, understanding the needs of your substrate and the application process is crucial for making the right coating choice. As well as knowing the substrate type, you need to know its environment, its use, the coating time parameters, and the likely ways it will fail. Here are some questions you need to ask before you can choose a high temperature coating:
What is the maximum temperature of the substrate that you wish to protect?
One of the most common reasons for coating failure is expecting high temperature coatings to perform outside of the temperature range they were manufactured to tolerate. Each coating type has a specific temperature range, and outside it the functionality and efficacy fails. Make sure not to understate the maximum temperature. Note also that many coatings are given the maximum continuous operating temperature and the maximum peak temperature.
For example, International Intertherm 50 is recommended for temperatures up to 540°C
What will the substrate temperature be during application?
There are high temperature coatings formulated for hot (up to 300oC) and ambient temperature application. A hot application may be required to avoid needing to shut down operations, spot coating problem areas, and generally not disrupting a facility. Before choosing the coating it is crucial to know at what temperature the application will take place; some coatings may be heat resistant but do not cure properly if heated during application.
For example, Jotun Epoxy HR can be applied on substrates up to 150oC
Is the substrate insulated?
Insulating steel structures is very common in industrial environments; it can minimise heat gain or heat loss, reduces costs, improves efficiency, and improves staff safety. The problem starts when water penetrates the insulation, collecting in the space between the insulation and the steel. When this happens it is the perfect environment for corrosion. If you are choosing a heat resistant coating for metal to combat CUI, that coating needs to be specially formulated for the purpose. It needs corrosion resistance, but it also needs to be able to be applied to hot substrates and deal with boiling water exposure.
For example, PPG HI-TEMP 1027 is designed to prevent CUI and can be applied to hot substrates
Heat resistant paint South Africa – An overview of products & services
Heat resistant coatings are used across a wide range of industries, as well as by homeowners and barbecue enthusiasts. As such, a wide range of products and services are available across the country, no matter your project. Heat resistant coatings should be applied by a trained professional. The manufacturers having business units in South Africa Include AkzoNobel Powder Coatings in Alberton, DuPont South Africa in Cape Town and NIC Industries South Africa in Johannesburg. Coatings from these and other manufacturers are trusted by professional heat resistant coating applicators; you can find a couple of these in the following table.
|Heat resistant paint specialist||Address|
|Thermo Shield SA||Cape Town 4D Montague Drive, Montague Gardens, Cape Town, South Africa|
|Power Kote||Johannesburg, Gauteng Office, 195 Booysens Road, Selby|
For information on where to find high temperature powder coating, please visit our page dedicated to powder coating services.
A selection of heat resistant coating products
In case you are not looking for a contractor but rather a product, we have compiled a sample of some heat resistant coating products available in South Africa. If you would like more information about heat resistant coatings, or would like to connect with one of our partners to coat your project, contact us! Our experts are here to help, just use the “Request a quote” button below the article and take advantage of our 100% free quote service.
|Heat Resistant Coating Product||Product Description||Applications||Theoretical Coverage|
|PPG HI-TEMP 1027||One component, silicone-based ceramic coating for carbon steel and stainless steel||CUI prevention in chemical/petrochemical, power, and offshore market segments up to 650°C||5.8m2 per litre for 125 microns|
|International Intertherm 50||Single components, silicone-based high temperature coatings for steel||Corrosion protection in fire stacks, chimneys, exhausts, vents and pipework up to 540°C||18m2 per litre at 25 microns|
|Jotun Solvalitt Midtherm||Single component silicone acrylic heat resistant coating for metal; steel and aluminium||Corrosion protection for insulated and non insulated surfaces up to 260°C||11.3m2 per litre|