High Temperature Coatings
High temperature coatings are paints, stains and other coatings designed to resist corrosion caused by extreme heat. They are most commonly used in industrial settings, such as refineries, power plants, offshore rigs, cement and concrete plants, chemical plants and military facilities.
High temperature coatings have a poor reputation for their quality. Many high temperature coatings suffer problems such as color instability and lack of available colors, as well as heat curing issues. They are frequently unable to withstand boiling water or application directly to hot steel.
Some of the more potent brands are able to overcome these shortcomings. They are able to be applied to directly to hot steel at a temperature of 500 degrees Fahrenheit, and are generally stable up to 1,000 F. Available in many colors, some high temperature coatings can be applied directly to rusted areas with no loss of effectiveness. These products can be used as high temperature coatings for gas turbine vanes or gas turbine blades.
One major area of research among high temperature coating companies is how to prevent corrosion under insulation. Corrosion under insulation accounts for a significant amount of the downtime and expense incurred by major industries. Many of the recent improvements in high temperature coatings are made to fight this problem. For instance, resistance to boiling water is important, because when rainwater hits a hot smokestack, it almost instantly boils. If a coating cannot resist the boiling water, then moisture seeps through and affects the metal beneath the coating.
Similarly, being able to apply to hot steel is key. Since many companies cannot afford to shut down their machinery, they end up applying high temperature coatings to hot steel. This often fails, leaving the coating weakened and susceptible to corrosion.
For high temperature coating on a smaller scale, there are high temperature powder coating masking tapes made of polyester or polymide available. The polyester tapes come in various sizes, and are designed to withstand temperatures up to 425 F for up to one hour. Polymide tapes are sturdier, able to withstand 400 F temperatures indefinitely, as well as short bursts of up to 700 F.