1. After the installation of main girder of gantry crane is finished, the rails of trolley are welded in order to make sure the height difference of joints ≤1mm, and the lateral truss girder gantry cranedislocation ≤1mm, the deviation of track center line and the girder web center line ≤4mm, lateral straightness ≤1mm/2m, and the length of rails≤10mm.

2. After the installation of main girder is finished, the allowed deviation of length of every main girder is ±10mm, and the allowed deviation of the center line of legs 'connection is ±0.5mm, the allowed deviation of sidewise bending(allow bending outwards, not allow bending inwards) is 8mm, and the allowed deviation of warping is 1mm.

3. In order to convenient for the assembly,  after installed, every segment and connecting plate should be marked.

4. layer board and cradle should be laying off welded. The diagonal line deviation of trimmer connecting plate≤8mm.

5. If the weld seam isn't marked full weld, so the weld height≥the thinnest plate' thick

6. The main girder arch camber and  the segment shouldn't deflect.