The grid structure should be made on a special mould to ensure the accuracy and interchangeability of the rods and nodes. The butt welds in the fabricating and assembling of the grid structure should meet the requirements of the secondary quality inspection standard specified in the current national standard "Code for Construction and Acceptance of Steel Structure Engineering" GBJ205, and other welds shall comply with the requirements of the tertiary quality inspection standard. The gusset plate of the welded steel plate joint should be cut with a grinding wheel cutting machine. The allowable deviation of the length of the gusset plate is ±2mm, the allowable deviation of the thickness is ±0.5mm, and the allowable deviation of the angle is ±20'. It can be checked with a square or a template, and the contact surface should be tight. For the semi-circular ball of the welding ball joint, the machine tool groove should be used. The surface of the finished ball after welding should be smooth and flat, and there should be no local protrusions or wrinkles.

For the allowable deviation of the welding ball diameter on the site structure: when the diameter of the ball is less than or equal to 300mm, it is ±1.5mm; when the diameter is greater than 300mm, it is ±2.5mm; when the diameter is less than or equal to 300mm, it should not be greater than 1.5mm ; When the diameter is greater than 300mm, it should not be greater than 2.5mm; the design wall thickness reduction should not be greater than 13%, and should not exceed 1.5mm; the allowable deviation of the misaligned side of the mouth should not be greater than 1mm. The bolt ball joints must not have cracks. The thread should be processed according to 6H precision and meet the requirements of the national standard "Common Thread Tolerance and Fit" GB197-81. The deviation of the distance from the center of the ball to the end face of the screw hole is ±0.20mm, and the allowable deviation of the angle of the bolt ball screw hole is ±30'.