Requirement 4.1 The materials used to manufacture flanges should comply with the design documents. When the design documents do not clearly specify, materials with properties better than Q235 should be used. 4.2 The thickness of the flange plate should comply with the design documents. Its tolerances should comply with the requirements of GB/T 709. 4.3 The size of the waist-shaped hole should comply with the design documents, and its diameter tolerance should not be greater than ±0.5mm. 4.4 The rotation of the waist-shaped hole should be ±5°, that is, the rotation angle β should not be greater than 10°. 4.5 The tolerance of the side length and outer diameter of the flange plate is ±3mm, and the tolerance of the pitch circle is ±1mm. 4.6 The roughness of the waist-shaped hole wall should be, and the roughness of the outer peripheral wall of the flange plate should be. 4.7 The flatness tolerance of the flange plate should not be greater than 1.0mm. The appearance of the flange plate should be clean, with no obvious rust and no obvious sharp edge burrs.