Seamless high temperature tubes made from iron-chromium-aluminium alloys (Powder metallurgy or conventional metallurgy), heat resistant casting alloys, or nickel based alloy are called radiant tubes. All above alloys have different compositions & choose according to application.
Highly customized to meet specifications, they are mostly used for gas heated or electrically heated furnaces. General designs include straight, U shaped and W shaped radiant tubes in any desired length. Used in extremely demanding environments, leak-proof and corrosion resistant are other unique features of radiant tubes. Heat resistant casting alloys allow operating temperatures up to 1100 °C. Radiant tubes can be used as standalone elements or in collaboration with bundle rod heaters. But when used with bundle rod heaters, can be used for temperatures up to 1400 °C and have superior performance. Some of the advantages of radiant tubes include :
Longer service life : Due to the capability of forming a dense and adhesive oxide film and excellent mechanical properties of radiant tubes, superior resistance to corrosion, thermal shock, sagging and atmospheric attack are provided which increases the operating life.
Superior power rating : Ferritic alloys provide higher power rating than any other metallic heating system
High temperatures and severe conditions : Powder metallurgy radiant tube can withstand carburizing and sulfurizing atmospheres. So furnace temperatures can be increased leading to reliable and cost efficient process.
Medium temperatures : When furnace conditions are not too demanding, a heat resistant casting alloy based radiant tube can prove to be the most economical choice.