High temperature coating for protection from heat
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 high temperature coating works to protect the substrate from variations and extremes of temperature without losing functionality.
In this article we take a look at the different categories of high temperature coatings and explain how to choose the right one for your project. Here you will also find some product suggestions and heat resistant coating contractors in Ireland.
Benefits of high temperature coatings
The primary task of a high temperature coating is to protect a surface (usually steel or other metal) from extreme temperatures and temperature fluctuation. However, the heat resistant coatings also have other benefits; they:
- Reduce thermal fatigue: High temperature coating improves performance of machinery and extends component life
- Allow for higher operating temperatures while limiting thermal exposure
- Have an effective temperature range up to 1000°C: Different formulations of high temperature coating for metal provide resistance to temperatures from -196°C to 1000°C
- Are abrasion resistant: Suitable for rough, heavy duty environments and applications
- Protect from corrosion under insulation (CUI): Heat resistant coatings for steel provide an extra layer of protection between the hot surface and insulation
High temperature coating types for different purposes
Essentially, heat resistant coatings can be divided into four types: liquid resin and polymeric coatings, powder coatings, metal and metal additive spray coating as well as ceramic coatings.
1. Liquid resin and polymeric coatings
The liquid resin and polymeric coatings are usually epoxy based, silicone based or multi-polymeric. These coatings exist as single and two component paints on water and solvent base. These liquid coatings are formulated to resist medium to high temperatures and they are applicable at new construction, on-site and as a maintenance coating. As a rule of thumb; the more silicone the coating contains, the higher the temperature resistance.
The absolute advantage of liquid high temperature coating is that it can be applied to heated or hot substrates without affecting the coatings properties and characteristics.
2. Heat resistant powder coatings
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. The reasons to consider using powders include environmentally friendliness (VOC free) and wide range of gloss and colour finishes.
Even though powders usually cannot be applied in hot substrates, they are becoming more and more popular as high temperature coating for steel and other ferrous metals.
3. Metal and metal additive coatings
These coatings are particularly used for corrosion protection combined with high temperature resistance. Thermal sprayed aluminium is particularly used as high temperature coating for steel for preventing corrosion under insulation (CUI) in onshore and offshore platforms and processing plants. Sprayed metal coatings are somewhat heat resistant however, it is common to apply a topcoat of another heat resistant coating to maximise the protection. Metal pigments are often used in liquid paints and powder as stabilisers for temperatures above 400°C.
4. Ceramic Coatings
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. Therefore the common applications of ceramic high temperature coatings include automotive underhood parts, vehicle exhausts and heavy industrial machinery.
Looking for a high temperature coating? – Consider this!
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 factors you need to consider before you can choose a high temperature coating:
Maximum operating temperature
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
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
Is the substrate insulated?
If you are choosing a high temperature 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
Reduce the risk of Corrosion Under Insulation with high temperature coating
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.
Heat resistant coating products and suppliers in Ireland
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 Ireland, 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 high temperature coating, 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|
|Rust-Oleum 4200 Heat Resistant Topcoat||Silicone-based topcoat with an aluminium finish for bare steel or primed surfaces||Heat resistance up to 425oC||16m2 per litre|
For information on where to find high temperature powder coating, please visit our powder coating services page.
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