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Method for leaving expansion joints of 11 kinds of kiln lining masonry refractory bricks
Dec 26, 2018

The expansion joints of various parts of the industrial furnace shall not reduce the strength of the masonry, and shall ensure that the outside air shall not enter the furnace or the gas in the furnace will escape outward. The position, structure and width of the expansion joints in different parts of the masonry shall be specified by the design.

When masonry is associated with equipment, components, embedded parts and holes, the dimensional change after expansion should be considered to determine the cold size or expansion gap of the masonry.

The expansion joints should be kept absolutely clean and there should be no blocks such as construction waste. The asbestos rope used to fill the expansion joint should be first immersed in a thin refractory slurry. The width of the expansion joint is usually 20 mm and should be filled with asbestos rope of 25 mm diameter.

1. The basic form of furnace wall expansion joint

The basic forms of furnace wall expansion joints are zigzag and straight through, as shown in Figure 1.

2, the method of leaving the vertical expansion joint

(1) The position of the vertical expansion joint of the masonry, the elevation of the low point and the high point shall be determined by the release line according to the design requirements.

(2) Once the position of the expansion joint is determined, it shall be determined according to the structural requirements of the expansion joint (either straight through or serrated seam, width, etc.) to determine the form of the masonry and to perform the inspection of the number of bricks.

(3) The masonry length outside the vertical expansion joint shall be controlled by means of drawing or clamping the wood template. When the expansion joint is zigzag, the vertical line should be controlled to control the verticality and width of the expansion joint; when the expansion joint is straight-through, the slightly inclined wooden panel should be used to control the straightness and width of the expansion joint.

3. Blockage of vertical expansion joints

(1) For straight-through vertical expansion joints, the asbestos rope can be hung vertically on the hob or temporary wooden pole.

Press the asbestos rope into the expansion joint and squeeze it during the laying.

(2) For staggered expansion joints, short asbestos ropes should be used, and the wooden strips should be properly pressed before filling.

Formwork form of refractory brick expansion joint

(3) When the expansion joint is filled with refractory fiber felt, the masonry on both sides of the expansion joint shall be constructed in sections. The refractory fiber felt is adhered to one side of the masonry by an adhesive, and the refractory fiber felt is squeezed when the other side masonry is built.

(4) When the filler is filled with plywood, cardboard or polystyrene foam board, it should be placed and clamped when the masonry is built. The thickness of the packing must meet the width requirements of the expansion joint.

4. Surface treatment of expansion joints

(1) When the asbestos rope is filled in the expansion joint of the masonry, the outermost asbestos rope on the working wall of the furnace shall be impregnated with graphite slurry or refractory mud along the brick joint, and the asbestos rope shall be kept flat with the wall surface. Straight, not convex and concave.


(2) When filling the felt or loose filler in the expansion joint of the masonry, if the filling in the joint is not uniform with the working wall surface in the furnace, a high-temperature binder or a small amount of short fibers of the same as the filler of alumina cement may be used. Mix evenly and use a hooking knife to flatten the expansion joint with the wall.


5. The retention of horizontal expansion joints


(1) When a metal pallet is installed on the horizontal expansion joint, the masonry of the lower masonry of the expansion joint shall be controlled by the actual elevation of the brick; when the upper part of the horizontal expansion joint is supported by the profiled brick support structure, it shall be first pressed. The design elevation marks the expansion joint on the nearby equipment, furnace shell or furnace skeleton to control the masonry of the lower masonry.


(2) During the masonry process, the size of the control line from the elevation should be detected at any time. If necessary, the positive or negative tolerance of the brick or the thickness of the grey joint should be used to make the whole brick layer reach the design elevation.


(3) When the expansion joint under the brick board cannot meet the design size, the brick in the lower part of the brick board can be processed. The thickness of the processed brick should not be less than 2/3 of the thickness of the original brick.


(4) When the structure supported by the upper part of the horizontal expansion joint is brick masonry, the actual elevation should be adjusted by the allowable error of the elevation, and the brick should not be processed.


6. Horizontal expansion joint packing method


(1) When the upper structure of the horizontal expansion joint is a profiled brick support structure, the filler shall be laid flat by the laying method according to the requirements, and then the support brick shall be built.


(2) When the upper support structure of the horizontal expansion joint is the supporting brick, the filling method should be used to fill the layer by filling.

7. Expansion joint of curved wall

For the expansion joint of the curved wall, a gap is left between the circular masonry and the metal casing to replace the expansion joint, and the filling is filled with a filling heat insulating material or refractory mud, such as perlite powder, vermiculite powder, etc. . As shown in Figure 5. The packing density in the expansion joint should be appropriate and uniform.


8. Furnace expansion joint


If a steel member is placed in the masonry of the furnace bottom, an expansion joint is left between the metal and the masonry to allow the metal to expand freely when heated, and the asbestos board is used as a filler in the joint.


When laying the bottom of magnesia brick or magnesia chrome brick, a 2~3mm thick expansion joint is placed every 3~4 bricks, and a 1mm thick cardboard is placed in the joint.


9, vault expansion joint


A straight through expansion joint is generally left at both ends of the dome. When retaining, in addition to considering the longitudinal elongation of the dome, the upward expansion of the furnace walls at both ends should also be considered. When the length of the vault exceeds 5 m, in addition to the expansion joints at both ends, the expansion joints shall be left in the middle of the vault according to the length of the sections. The expansion joint of the arch is covered with a layer of flat brick, as shown in Figure 6.


10. Hanging furnace top expansion joint


On the suspended roof, it is common to use an expansion joint on the side and bottom of the brick adjacent to the two sides of the wall, and the asbestos is filled in the joint, as shown in Fig. 7. The expansion joints left on the back of the first row of transverse arch bricks are identical to the sides.

11. Pipeline lining expansion joint


The method of leaving the expansion joint in the pipe is shown in Fig. 8. The transverse expansion joint ensures that the masonry expands in the longitudinal direction, while the circumferential seam between the inner liners ensures expansion in the diameter direction.


12, the expansion of the boiler furnace wall expansion joint


(1) Basic requirements. The boiler furnace wall shall be provided with expansion joints according to the technical documents of the equipment. The width deviation shall be plus or minus 3 mm and the boundary shall be flat. When there is no design, the average value of expansion joints per m length of masonry is 5~6mm for clay brick masonry and 6~7mm for high alumina brick masonry. The expansion joints of various parts of the furnace body are reserved. It is not allowed to reduce the strength of the masonry, but also to ensure the tightness of the furnace.


(2) The expansion joint is left behind. The asbestos rope packed in the expansion joint shall be soaked in the refractory mud in advance. In order to make the asbestos rope tightly fill the expansion joint, the diameter of the asbestos rope should be slightly larger than the gap of the expansion joint. In most cases, the width of the expansion joint is 20mm, with asbestos rope diameter of 25mm. The outermost asbestos rope of the expansion joint to the fire surface shall be flush with the refractory brick wall and shall not be convex and concave.

The expansion of the expansion joint in the furnace wall is shown in Figure 9. It is advisable to extend the wall or flame wall of the furnace into the refractory brick layer of 90~95mm. When the furnace wall is long, an expansion joint can be added in the middle, as shown in FIG. Except for the asbestos rope, the exposed part of the wall of the furnace wall shall be covered with a layer of flat brick, which is the same as the requirements of Figure 7-6.


(3) The expansion of the expansion joint of the metal members in the furnace wall. In order to ensure the free expansion of the boiler after heating, the outer wall of the wall, the box, the drum, etc. should be wound with a diameter of 10~20mm asbestos rope; the casting inside the wall should be filled with 10~15mm thick asbestos board; The expansion joint of the steam drum is to form a circular arch along the circumference of the steam drum, and a diameter of 25 mm asbestos rope is filled between the steam drum and the arch.


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