General provisions

In addition to the "Grid Structure Design and Construction Inspection" JGJ7-91 and "Grid Structure Engineering Quality Inspection and Evaluation Standard" JGJ78-91 or the industry standard "Steel Grid Bolt Ball Node" JGJ75, the production, installation and inspection of the steel grid .1-91, "Steel Grid Welded Ball Joints" JGJ75.2-91, "Steel Grid Inspection and Acceptance Standards" JGJ75.3-91 and other relevant grid standard standards, should also comply with national standards "construction engineering quality Inspection and evaluation standard GBJ301-88, current national standard "Steel structure engineering construction and acceptance specification" GBJ50205-95 and "Bolt ball joint steel mesh weld seam ultrasonic flaw detection and quality classification method" JG/T3034.2-1996, "welding JG/T3034.1-1996, and other national standards for steel and steel, etc.

1. material

The materials used for steel grids vary according to their location in the grid. For example, rods, seals, cones, sleeves and welded hollow spheres are all Q235 steel or 16Mn steel; solid bolt balls are 45. No. steel; bolts, pins or screws are 40Cr, 40B, 20MnTiB; 8.8S high-strength bolts can be made of 45 steel.

The materials used in the production must meet the design requirements. If there is no factory certificate or if there is any doubt, it must be tested according to the current national standard "Steel Structure Engineering Construction and Acceptance Specification" GBJ50205-95 for mechanical performance test and chemical analysis. Standard and design requirements are available for use.

2. Quality Evaluation

At present, the production and installation process of the grid project has two forms. The first is that the production and installation of the grid are completed by the production and installation qualification; the second is that the components of the grid are manufactured by professional products. Provided by the factory, it is installed by the construction team with installation capability. Due to the characteristics of the grid itself, most of the grid projects are currently produced and installed by the manufacturer.

The grid project is part of the structural division of a single building project. If the grid project is completed using the second form described above, the joints, bars and various fittings shall be in accordance with the "Steel Grid Bolt" during the production process. Ball node "JGJ75.1-91 or "Steel grid welding ball joint" JGJ75.2-91 and "Steel grid inspection and acceptance criteria" JGJ75.3-91 for inspection, the test results do not participate in the quality assessment of the main part. If the grid project is completed by the first form mentioned above, in the production and installation process, each sub-project (node fabrication, rod fabrication, installation, painting, anti-corrosion, fire prevention) shall be evaluated according to the quality inspection of the grid structure engineering. The standard "JGJ78-91" is inspected, and the test results are all involved in the quality inspection and assessment of the main division project.

If the quality of the sub-projects included in the grid project is all qualified, the overall quality of the grid structure can be assessed as qualified. If the quality of the sub-projects included in the grid project is all qualified, and 50% or more of them are excellent, the overall quality of the grid structure project can be assessed as excellent.

According to the requirements of "Construction Engineering Quality Inspection and Evaluation Standards" GBJ301-88, the quality rating of the sub-projects shall be carried out according to the following rules:

qualified:

(1) Ensure that the project must meet the requirements of the corresponding quality inspection and evaluation standards;

(2) The basic project sampling inspection department (pieces) shall comply with the requirements of the corresponding quality inspection assessment criteria;

(3) Among the points that are allowed to be sampled by the deviation item, 70% or more of the measured values shall be within the allowable deviation range of the corresponding quality inspection evaluation standard.

excellent:

(1) Ensure that the project must meet the requirements of the corresponding quality inspection and evaluation standards;

(2) The basic inspection items (pieces) of each basic inspection project shall comply with the requirements of the corresponding quality inspection assessment criteria, and 50% or more of the qualified personnel shall meet the excellent requirements, and the project shall be excellent. The number of good items shall be 50% or more of the number of inspection items;

(3) Among the points that are allowed to be sampled by the deviation item, 90% or more of the measured values shall be within the allowable deviation range of the corresponding quality inspection evaluation standard.