What are the regulations for the construction of grid structures?

　　 I. General Provisions 　　 (1) The steel material must meet the design requirements; in the absence of a factory certificate of conformity or when doubts exist, mechanical property tests and chemical analyses must be carried out in accordance with the current **standard, the ‘Code for Acceptance of Construction Quality of Steel Structure Projects’ GB50205—2001. It may only be used after it is proven to meet the standards and design requirements. The quality of concrete shall meet the current **standards

1. Strictly follow the design drawings and **specifications in organizing construction and quality inspections to ensure project quality. 　　2. The processing of components follows a \"four-inspection system\", namely self-inspection, mutual inspection, specialized inspection, and final inspection for confirmation. 　　3. For each component, record in a table the operator responsible for each processing step, the inspector, and the quality status. 　　4. Material requirements: Materials entering the factory must come with a warranty certificate; after arrival, random inspections are carried out in accordance with relevant standards to check the chemical composition and mechanical properties of the steel, which must meet the specified standards and design requirements. 　　5. The grid members, cone heads, end plates, sleeves, high-strength bolts, set screws, and supports are all manufactured in strict accordance with the requirements of the design drawings. Throughout the entire production process, it is essential to adhere to the principle that raw materials and components that fail inspection shall not be used in production; defective semi-finished products shall not be moved on to the next stage of processing; and faulty parts shall not be assembled or welded together. 　　6. After the steel pipes have been cut to size and the aforementioned components have been manufactured, they must all be inspected by the quality control department; only after it is confirmed that they meet the requirements specified in the drawings can they be assembled and spot-welded. 　　7. The assembly and spot welding of the rod members are carried out on a dedicated assembly table. The weld gaps between the steel pipes and the end plates (conical heads) are even on both sides, their dimensions are controlled precisely, and an appropriate amount of space is reserved for weld contraction, so as to ensure the length of the rod members after welding. 　　8. After the members are welded, ultrasonic or magnetic particle testing is used to inspect the quality of the welds. 　　9. During the manufacturing of bolt balls, both the chemical composition and mechanical properties of the material must meet the requirements of the specified steel grade. The blanks must be free of cracks, and their roundness must be within specified limits; only then can they be processed on specialized machines for precise indexing, surface cutting, drilling, and tapping. After a ball is completed, the operator should check it in accordance with the requirements specified in the drawings, apply a stamp and assign a serial number to it; it can only be put into use after passing inspection by the quality control department. 　　10. After welding the grid members, stamp the welder’s code on them to assign responsibility to a specific person. 　　11. Welders may begin welding only after passing the assessment conducted by the **relevant authorities. 　　12. Conduct comprehensive tensile failure tests on the nodes to examine the ultimate tensile bearing capacity of high-strength bolts, the strength of the members and welds, as well as the shear strength of the conical base plate (or cover plate). 　　13. After derusting the surfaces of all components, anti-corrosion coating is applied. 　　14. Before installation, each component shall be rechecked in accordance with the drawings; after assembly, a torque wrench shall be used to check the tightness of the grid bolts, and the elevation of the grid shall be checked throughout the assembly process. 　　15. Once the grid is installed, it is necessary to check whether the welded areas are secure, and fill any excess ball holes with putty.