Heat resistant coating for high temperature 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 (or thermal management coating) works to protect the substrate from variations and extremes of temperature without losing functionality. As well as protecting from heat, these coatings:
- Protect from corrosion under insulation (CUI): High temperature coatings for steel provide an extra layer of protection between the hot surface and insulation
- Effective temperature range up to 1000°C: Different formulations of heat resistant coating for metal provide resistance to temperatures from -196°C to 1000°C
- Abrasion resistant: Suitable for rough environments
- Reduce thermal fatigue: Heat resistant coating improves performance of machinery and extend part life
- Allow for higher operating temperatures while limiting thermal exposure
In this article we look at the different categories of heat resistant coating, how to choose the right one for your project, and where to find products and contractors in the UK.
The different types of heat resistant coating
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 coatings can be divided into four types:
1. Epoxy-based, silicone-based, multipolymeric paints – Single or two component, water- or solvent-based, these paints are formulated to provide resistance to high heat when applied at new construction, on-site and as a maintenance coating. Usually the more silicone, the higher the temperature resistance. For medium to high temperature protection. Liquid paints have the benefit of being able to be applied to hot substrates without affecting the coating.
2. Sprayed metal and metal additive coatings – These coatings are particularly used for corrosion protection combined with heat resistance. Thermal sprayed aluminium is particularly used as high temperature coatings for steel for CUI prevention in onshore and offshore platforms and processing plants. Metal pigments are often used as stabilisers for temperatures above 400°C.
3. Ceramic coating – The heat resistance properties of ceramic coating are well known, and some of the highest heat coatings available are ceramics. Heat resistant ceramic paint also provides corrosion protection and chemical resistance and a hard finish.
4. Powder coating – As well as being corrosion resistant, high temperature powder coatings have been developed for heat resistance to temperatures ranging from 200oC to 550oC. The powders are usually epoxy and silicone-based (like the liquid paints), and silicone-based powders perform better at higher heats. These have the benefit of being VOC free and having a wide range of gloss and colour finishes. They are becoming more and more popular as heat resistant coating for metal.
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 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.
For example, International Intertherm 50 is recommended for temperatures up to 540°C
Is the substrate insulated?
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
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.
For example, Jotun Epoxy HR can be applied on substrates up to 150oC
Where to find high temperature coating manufacturers and specialists in the UK
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. Below is a table outlining just a few of the products and their costs, as an indication. Heat resistant coatings should be applied by a trained professional. 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.
For information on where to find high temperature powder coating, please visit our powder coating services page.
|Heat Resistant Coating Product||Product Description||Applications||Price||Theoretical Coverage|
|PPG HI-TEMP 1027||One component, sillicone-based ceramic coating for carbon steel and stainless steel||CUI prevention in chemical/petrochemical, power, and offshore market segments up to 650oC||£310-320/gallon (3.8L)||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||£160-170/6L||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 260oC||£90-100/5L||11.3m2 per litre|
|Rust-Oleum 4200 Heat Resistant Topcoat||Silicone-based topcoat with an aluminium finish for bare steel or primed surfaces||Heat resistance up to 425oC||£130-140/5L||16m2 per litre|
High temperature coatings for steel combat CUI
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. The trapped moisture has the potential to cause rapid rusting and corrosion on the surface of the steel.
CUI is particularly insidious as it can go undetected under insulation until the problem is severe. If it remains undetected, it can lead to shutdown of an entire facility, or even a safety incident. This is why high temperature coatings for steel are so important – they can coat the steel surface and protect it from the dangers of corrosion under insulation.