Construction of Furnace Refractory Line: Arch, Vault and Suspended Vault

1. The arch as well as its column wood should comply with the selecting criteria of load-bearing structure in the existing national standard Construction and Acceptance Specification for Wooden Structural Engineering. The wood can be chosen according to the actual situation in the region, but it cannot be lower than grade Ⅲ. 

2. The radian of the arch should comply with the design. Its surface should be smooth. The setting of arches should be proper and firmly. And it should be checked and accepted before the construction of the arch or vault. 

3. Before the construction of vaults, the arch foot beams and steel columns should be close together tightly and pass the inspection. When constructing vaults with adjustable steel frame, the steel frame and rod should be adjusted and fixed and pass the inspection. 

4. The surface of the arch foot should be smooth and the angle should be correct. The arch foot cannot be made level by thickening the brick joints. 

5. The arch foot bricks should be laid close to the arch foot beams. If there is masonry behind the arch foot bricks, the masonry should be completed before the construction of the arch or vault. Insulation bricks and diatomite bricks should not be constructed behind the arch foot brick. But behind the arch foot bricks of vaults built with insulation bricks, the same insulation bricks can be used. 

6. Unless there are specific provisions, the arch and the vault should be laid with joints staggered with each other. Pull a line longitudinally to keep the arch and the vault straight. Except the 160mm-thick arch or vault, the bricks of the first and last rings should be avoided being cut and made level with 230×172×65/45 and 230×172×65/55 vertical wedge bricks if necessary. 

7. The bricks in the leveling layer of the fire clay brick arch or vault can be replaced with corresponding refractory castable materials. 

8. The arch and vault with different spans can be laid by rings. The brick ring should be flat and at the same center line. 

9. The arch and vault should be laid symmetrically from the arch foot to the center. Avoid laying the wedge bricks upside down. 

10. The radiation seams of the arch and vault should coincide with the radial direction. The inner surface of the arch and vault should be flat. 

11. The lock bricks should distribute along the center line symmetrically and evenly. A lock brick should be inserted into the arch and vault when the span is less than 3m, 3 lock bricks when the span is more than 3m and 5 lock bricks when the span is more than 6m. 

12. The depth of the lock brick into the arch or vault should be 2/3-3/4 of the length of the brick. The depth should be consistent in the same arch or vault. The symmetrical lock bricks should be inserted evenly simultaneously with a wooden mallet. When using a hammer, pad with a wood plate. 

13. Do not use lock bricks with more than 1/3 of the thickness cut or a wedge broad face. The vault should be finished in the same day. After the lock bricks are inserted, fill the seams with mud. 

14. The spherical vault should be constructed by combining metal hook and arch. It should be constructed ring by ring. The door should be closed in time and the stubble should not be more than 3 rings. The closed door bricks should be distributed evenly. The geometry dimensions and radiation seams should be constantly checked. 

15. Suspended bricks of the suspended flat top should be laid from the center to the sides. The inner surface of the suspended flat top should be smooth. If there are gaps between the suspended bricks and suspended beams, plug it with thin steel plates. When constructing the suspended flat top, expansion joints should be reserved between the side bricks and the wall. Slope roof should be constructed from the turning point to the two ends. 

16. Suspended bricks should be pre-built, selected and numbered. Process them if necessary. Note that there should be no cracks in the stress points of the suspended bricks. 

17. After the construction of suspended bricks is completed, fill up the joints of the roof and then lay the insulation layer. 

18. After the construction of suspended bricks with suspenders and nuts is completed, tighten the nuts. When tightening the nuts, avoid the rising of the bricks and keep the hook close to the top edge of the bricks. 

19. The suspended vault should be laid by ring. The seams should be parallel to each other and perpendicular to the longitudinal center line of the roof. 

20. The suspended vault should be locked ring by ring and the locking degree of each ring should be consistent. After the lock bricks are combined tightly, the pin should be installed in time. 

21. Before dismantling arches with a span of more than 5m, measure the sinking of the vault bricks and make signs. After dismantling the arches, record the sinking of vaults. 

22. Before dismantling the vaults, complete the construction of the grooves at the arch foot and tighten the nuts of steel rods. After the vaults are dismantled, the lock bricks should be tightened. Before dismantling the arches, complete the construction of suspending structure. 

23. When filling up the joints and laying insulation products, expose the metal suspending pieces outside the mud and insulation products. 

24. The reserved holes can be filled with shaped bricks, standard bricks or castable according to the size.