1. Shrinkage and expansion of refractory castable

Castable refractory castable in... During the heating process, there will be two volume shrinkage when dehydration at 50℃ ~ 200℃ and sintering at 900℃ ~ 1000℃. In other temperature ranges, heating will cause the castable to expand. Go through After secondary heating, the castable generally no longer shrinks.

In order to prevent the stress caused by the volume change from causing damage to the castable, the lining must be divided into cells with a diagonal size of no more than 1.5m, and the partition of the pouring zone with expansion and contraction gaps at the boundary of each pouring zone.

2. Influence range of expansion joint

The size of the castable gap should maximize the free expansion of the pouring material in each cell, and the expansion joint with the appropriate location can also become the control joint. In the high temperature section (> 600℃), the width of the expansion joint should be controlled at 3 ~ 4mm according to the spacing of the expansion joint. The expansion and control joints are arranged on the plane above and below the convex Angle 200mm, rather than in the convex Angle and the sharp cone. The cracking tendency of castable on both sides of expansion joint and control joint is large, and the nail density can be appropriately increased.

3, expansion joint width control

The width of the expansion joint is related to the operating temperature and the controlled line length. The temperature is higher, the control length is longer, and the expansion joint can be appropriately widened. In relatively low temperature areas (<400 ° C), the equipment housing can be directly used castable, no thermal insulation layer. Under such conditions, inserting 2mm thick cardboard or plastic film every 1.5m can meet the requirements of expansion space.

4, expansion seam position of the first

When determining the expansion position, the reasonable arrangement of the vibration process should be taken into account, and the vibration of the castable on one side of the gap should not affect the castable that has finished the vibration and started the initial hardening. The position of the expansion joint avoids the stressed part, the hole of the furnace skeleton and the inner lining. In the area with complex shapes, such as edges, ridges, etc., the expansion joint suitable for its surface should be set at the convex Angle and the curved surface with small curvature radius. When the two pouring surfaces intersect into a concave Angle, a ┖ expansion joint should be set at the concave Angle. The lining diagram should show the location and size of the expansion joints in the main parts. If the working temperature of the pouring material exceeds 1200 ° C, an expansion joint with a width of more than 3mm should be set and the fiber felt should be stuffed into it.

5. Control the setting of the joint

Due to the shrinkage of castable will cause cracking, it is necessary to set the control joint at about 200mm of the convex Angle, so that the shrinkage crack can occur in the predetermined, relatively safe part. The setting of the control joint can be filled with paper, paraffin or thin wood at the predetermined gap part, and the combustible or lost materials are poured under high temperature conditions, and the combustible materials are burned or lost, leaving the control joint.