Optimizing the sealing of tubular heating elements

Abstract: Tubular heating elements, produced by Backer AB are today commonly used, serving as systems for intelligent heating in automotive, medical and household industries. Tubular heating element consists of a mantle, resistance wire, electrical insulation (magnesium oxide) and a sealing. When active, an electric current transfers heat from the resistance wire of the heating element to the surroundings without the risk of current leakage. This is due to electrical insulation obtained by magnesium oxide (MgO), which possesses low electric conductivity making it an excellent electric insulator. MgO is hygroscopic and in the presence of moisture, MgO absorbs water and forms magnesium hydroxide (Mg(OH)2), which if hydrated causes bad electrical insulation of heating elements. This makes moisture a major problem and necessitates insulation through the usage of a sealing. Today, the application of sealing takes place in the latter stages of production, increasing the risk of moisture penetration of the heating elements during fabrication.