The electric heating tube housing is made of carbon steel, stainless steel (corrosion resistant), copper (good plasticity and thermal conductivity), titanium, tetrafluoroethylene, and the like. In addition, the heating temperature conditions have certain influence on the selection of materials. Generally, the heat resistance temperature of stainless steel 304 is 600 ° C. When the heating temperature reaches 800 ° C, it is necessary to select stainless steel 316 or 316L, when it reaches 1000 degrees, It is necessary to choose stainless steel 310S to ensure the service life of the electric heating tube. The reason why the electric heating tube can generate heat is that the electrothermal alloy wire is indispensable, that is, the electric resistance wire that we usually know. The electric heating tube is heated at a high temperature, so nickel-chromium-aluminum and iron alloys with high strength and high heat resistance are selected.
In the detection of electric heating pipes, the environmental requirements are relatively high, and thus more stringent research is required in the production of materials and processing techniques. The electric heating tube is obtained by placing the electric heating element in the metal tube with the extraction rod, and the void portion is closely filled with the crystalline magnesium oxide powder having good heat resistance, thermal conductivity and insulation, and the screw sleeve for fixing installation is added at the tail portion. The barrel and the sealed porcelain head, and finally the electric heating element processed by other processes. In the heating medium of the electric heating tube, different media have different characteristics, such as: water (oxidation), some chemical media (acid |, alkali corrosion), molten salt (chloride ion corrosivity), etc. There are different requirements for the selection of materials when heating the outer casing of the tube. It is necessary to use a voltage of 1800V for the breakdown test to ensure that the shape of the resistance wire is evenly wired and the heating effect of the electric heating tube is ensured. After being heated, the most indispensable problem arises, insulation.
The whole body of the heating tube is basically an electric conductor, which requires excellent thermal conductivity and excellent insulating magnesium oxide to fill the gap between the electric resistance wire and the outer casing to have the effect of insulating and conducting heat, and the insulating ceramic head is used at the tail to cooperate with 704. The high temperature rubber seal achieves the best insulation (insulation degree ≥ 500MΩ) to ensure the safety of the electric heating tube when heating.