First, determine the location and spacing of expansion joints
Usually, expansion joints need to be set at the corners of the furnace, the junction of different materials, around the furnace door, and the middle part of the long wall where thermal stress concentration is likely to occur. For general industrial furnaces, the spacing of expansion joints can be around 2-4m. When the operating temperature is high and the furnace size is large, the spacing should be small; otherwise, the spacing can be appropriately increased.
Next, prepare the expansion joint material
Commonly used expansion joint materials include ceramic fiber, polystyrene board, rubber board, etc. These materials have good elasticity, high temperature resistance and corrosion resistance, and can adapt to the extrusion and friction of refractory castables when they expand due to heat.
Construction method of reserved expansion joints
1.Vertical expansion joint: The pre-prepared expansion joint material can be vertically inserted into the formwork according to the designed position and width, and then poured. During the pouring process, care should be taken to prevent the castable material from entering the expansion joint and affecting its expansion and contraction function.
2.Horizontal expansion joint: You can first lay a layer of expansion joint material on the base layer, and then pour the refractory castable on it. You can also lay the expansion joint material flat on the surface of the castable after pouring a certain thickness of castable, and then continue to pour the upper layer of castable.
3.Annular expansion joint: The expansion joint material can be made into a ring, put on the furnace body or pipeline, and then poured. Or during the pouring process, the expansion joint material is embedded in the refractory castable at a certain interval to form an annular expansion joint.
Treatment and protection of expansion joints
After the construction is completed, the debris in the expansion joint must be cleaned to ensure that the width and space meet the standards, and high-temperature sealant must be applied to prevent impurities from entering. Only by strictly following these steps and allowing the expansion joint to function normally can we effectively avoid material damage caused by thermal expansion and contraction and ensure the safe and stable operation of the furnace.