As one of the three major thermal equipment in glass production, the installation of tin bath bottom bricks is a high-standard and strict job. The installation quality of the bottom bricks directly affects the production of float glass after production, and is related to the service life of the tin bath and the quality of glass products. Since several tons of glass float on the surface of the tin liquid, and the density of tin is greater than the bottom bricks, the tin liquid will sink in the later stage of the tin bath, which is easy to damage the studs and cause the bottom bricks to float, so the construction must be strictly in accordance with the design.
General requirements for bottom brick laying
(1) The bottom brick laying should be carried out by a dedicated person in a strict and orderly manner;
(2) Correct construction methods and necessary special tools should be used, and the bottom bricks should be handled and placed gently;
(3) Strictly follow the construction procedures, otherwise graphite gaskets will be missed;
(4) Do a good job of vacuum cleaning and protection in each process;
(5) Before the tin bath is put into use, all metal gaskets in the bottom brick seams of the tin bath must be removed, and no leakage is allowed.
Key points for laying bricks at the bottom of the tin bath
01 Transportation of bottom bricks
Transportation is the first step of construction. All six sides of the bottom bricks have been processed and polished. According to the construction requirements, the bottom bricks of the tin bath are transported to both sides of the tin bath in sequence. The number of stacking layers is based on one layer, and the bottom bricks transported to the surrounding of the working surface are covered.
02 Review of the steel structure of the bottom of the tin bath
Check whether the distance from the 1# column of the tin bath to the center line of the 1# small furnace of the melting furnace is consistent with the design drawings; measure whether the horizontality and elevation of the bottom plate of the bath can meet the design requirements; whether the distance from the 1# column to the entrance lip plate can meet the size of the floor tiles; whether the longitudinal center line of the tin bath is consistent; whether the floor rust removal is thorough.
03 Laying out the bottom bricks
After the review of the steel structure of the bottom of the tin bath meets the requirements, lay out the lines. Take the center line of the column as the reference, mark the control line of each section, generally one control line is placed for every three rows of bricks, so that the error of each row of bottom bricks can be better controlled; mark the design elevation of the upper surface of the floor tile on the side plate of the tin bath, and mark all the points and lines clearly.
04 Bottom brick masonry leveling
If manual welding bolts are used, the bottom bricks must be pre-arranged before laying. Workers entering the trough need to change into soft-soled cloth shoes. Use a vacuum cleaner to clean the trough before laying the bottom bricks. The masonry floor tiles should be positioned from the inlet end of the tin bath and installed from both sides of the center line. Use a special crane to lift the first positioning brick to the position, drop the brick steadily, press the four corners of the brick hard to confirm the stability of the brick, and use a leveling instrument to measure the four corners of the plane on the brick. The elevation is within ±0.5mm. If the reading does not meet the requirements, use a leveling instrument at the four corners of the brick to Steel gaskets of different thicknesses are used for adjustment until the requirements are met, but the maximum adjustment distance between the bottom brick and the bottom plate of the tin bath is no more than 2mm, and all bottom bricks and side bricks are carried out in the same way. The longitudinal and transverse brick joints of the bricks are separated by expansion plates of different thicknesses to ensure the reservation of the brick joints. After every three rows are laid, the expansion plates are removed, the bottom bricks are wiped dry with a dry cloth, vacuumed clean, the brick joints are sealed with tape, and covered with fiber cloth. In terms of design, there should be a row of reserved processing bricks from the wide section to the contraction section. Because the longitudinal distance is long (dozens of rows of bricks), cumulative errors will occur. To ensure that the brick joints of each row of bricks can meet the requirements, when there is still one row of bricks left from the wide section to the contraction section, it will be reserved, and then the bricks will be laid from the contraction section to the narrow section. Before installing the brick bottom, the large tin bath cover should be installed first, and the lifting height of the large cover should be slightly higher than the height required by the operator. It is advisable to not install the side trough plate first, and build a 1500mm×2000mm steel platform on the outside of the edge of the tin trough. The bottom brick platform is hoisted into the trough, and each brick required for masonry is passed through the platform by manual hoisting, and then the brick is placed at the corresponding bottom of the trough.
05 After the bottom brick masonry is completed, the trough is thoroughly cleaned and stud welding is performed
To ensure the firmness of each stud welding, a stud welding test should be performed before welding to check whether the material of each stud meets the design requirements, whether the diameter of the magnetic ring matches the stud, and whether the angle and depth of the small hole under the cone tip of the stud meet the requirements. The bottom plate of each brick hole should be cleaned. If the brick hole at the bottom of the trough is damp, it should be blown dry with a hot air blower and cleaned, and finally the stud welding is performed. Put a special sleeve (with φ43 0mm×300mm steel pipe is suitable), then use a flat drill to rely on the inner wall of the casing, drill the mark of the fixing bolt position on the steel plate, and remove the bottom brick to weld the fixing bolt. Use an arc welder to manually weld the bolts. After welding, keep them warm and cool them to room temperature. Then use a torque tester to test the tensile strength of each bolt after welding. The test torque is required to reach 28N·m, and then use a 0.5kg hand hammer to hit the root of the bolt for re-inspection and remove the welding slag. The inspection workers should be responsible for a dedicated person. Cracks, pores, and shrinkage are not allowed at the welding point between the bolt and the steel shell. Unqualified ones must be pulled out, and the bottom plate of the original welding point must be polished flat and re-welded with qualified bolts.
06 Bolt hole sealing
After welding the fixing bolts, the bottom bricks of the slot can be hoisted, and the bolt holes are sealed after the bottom bricks are in place. First calculate the required amount of graphite powder (to ensure that the filling density is >1.3g/cm3) and put it into a small bag. After confirming that the bricks are placed properly and cleaning the bolt holes and tapered holes with a vacuum cleaner, fill the gaps between the bolts and brick holes with graphite and tamp them manually with a special sleeve; after the graphite powder is tamped and inspected by a dedicated person, place the graphite washers and steel washers, and tighten the nuts. The tightening degree of the nuts should be hand-tightened. After the graphite powder is filled, carefully check the installation of the bolts and vacuum clean them. To protect the bottom bricks and prevent debris from falling into the brick joints, the expansion joints should be sealed with tape, and plastic cloth and fiberboard should be laid on the bottom bricks.
07 Ramming of sealing materials
① Mixing and stirring of sealing materials The sealing materials should be mixed with water according to the instructions and stirred evenly before use. They can be stirred manually or with a mixer, but after stirring, they should be sieved with a 3.35mm sieve to remove the material lumps.
② The sealing material should be rammed after 5 rows of bottom bricks have been laid (to prevent vibration from causing displacement of surrounding bricks). Before ramming, fix the gap between the side wall bricks and the groove side (side board) with a wooden wedge, clean the brick holes with a vacuum cleaner, moisten the bolt holes with a wet cloth or brush, and then place the protection and feeding hopper above the inverted cone hole to start tamping. The first amount of sealing material added should cover the bottom bolts of the groove (about 60mm high). The sealing material is added while tamping to prevent stratification until the hole is filled and 10mm above the brick surface. The last feeding height is not less than 20mm.
③ Use a trowel to scrape the material pile above the brick surface, then flatten and smooth the joints, and cover them with 120mm×120mm×20mm rubber (or plastic sheet) for maintenance. The tamped sealing material is qualified if it does not produce sand when rubbed with fingers.
④ To ensure the quality of ramming, the ramming operation must be carried out continuously until it is completed. It is strictly forbidden to add materials in layers and ram layer by layer.
⑤ The ramming material must be used up within 1 hour after each 2 mixings, otherwise it must be re-prepared.
08 Filling of edge sealing material
① The mixing and stirring method of edge sealing material is the same as that of hole sealing material, and water is added according to the instructions. The mixed material must be used up within 1 hour.
② After all the bottom bricks of the tin trough are installed and qualified, remove the wooden wedges around, clean the gap between the side wall bricks and the side panels, and cover the surrounding bottom bricks with plastic cloth before ramming.
③ Place the special hopper in the gap between the bottom bricks and the side wall bricks of the trough, pour in the mixed edge sealing material, and tamp it with flat steel or special tools.
④ The edge sealing material must be filled densely, and it is strictly forbidden to construct in sections and block the expansion joints with edge sealing materials. 09 Pay attention to the position of the observation hole. When laying the breast wall bricks and the top cover bricks of the tin bath, pay attention to the position of each observation hole. The upper breast wall bricks and the top cover bricks should be laid simultaneously. The top cover bricks should be laid in sequence from the entrance section to the back. After laying one row, the next row can be laid. It should be noted that the position of each heating hole should not be left wrong. The height difference of the lower surface between the two top cover bricks should not be greater than 2mm, and the height difference of the lower surface of the entire top cover brick should not be greater than 6mm. Ensure the gap between the top cover bricks and the breast wall bricks on both sides.
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