See the national standard GB 50205-2001<+0. Main control items: 4.2. 1 The varieties, specifications and properties of steel and steel castings shall meet the current national product standards and design requirements. The quality of imported steel shall meet the requirements of design and contract standards. 4.2.2 In any of the following circumstances, steel products shall be sampled for re-inspection, and the re-inspection results shall meet the current national product standards and design requirements. 1 imported steel; 2 mixed batch of steel bars; 3 thick plate with thickness equal to or greater than 40 mm and designed with Z-direction performance requirements; 4. The safety level of the building structure is Grade I, and the steel used as the main stress component in the long-span steel structure; 5 design steel with reinspection requirements; 6 steel with suspicious quality. 4.3. 1 The varieties, specifications and properties of welding materials shall meet the current national product standards and design requirements. Inspection quantity: all inspections. 4.3.2 The welding materials used for important steel structures shall be sampled for re-inspection, and the re-inspection results shall meet the current national product standards and design requirements. 4.4. 1 High-strength large hexagon-head bolt connection pair, torsional shear type high-strength bolt connection pair, high-strength bolts for steel grid, ordinary bolts, rivets, self-tapping nails, nails, anchor bolts (mechanical and chemical reagents), anchor bolts, nuts and washers and other standard parts. Its varieties, specifications and performance should meet the current national product standards. High-strength hexagon-head bolt connection pair and torsion-shear type high-strength bolt connection pair should have inspection reports on torque coefficient and fastening axial force (pre-tightening force) respectively. And so on, to name a few, see for yourself.