Many electric heating tube manufacturers use magnesium oxide powder treated with silicone oil. The reason is that the internal temperature of the water-fired tube is low, and the magnesium oxide treated with silicone oil does not absorb moisture, which is easy to control during the manufacturing process of the electric heating tube. But when the surface power density is higher. Or due to the thick scale of the outer tube. The internal temperature rises. Silicone oil will decompose at a temperature above 500 ℃ for a long time to produce gas (hydrogen. Carbon dioxide). This gas generates huge pressure inside the electric heating tube. This produces a burst tube. One reason for the burst tube is 91, after the tube has a hole. Water enters the electric heating tube. After the heating tube is energized. Water quickly vaporizes. Generate pressure and burst the outer tube. Or when not in use for a long time. Magnesium oxide and water form a larger volume of magnesium hydroxide.