Quality control of main works of steel structure.

    (1) Quality acceptance of steel members.The processing of steel members has been carried out in the factory, so the quality acceptance of steel members entering the site is very important. In addition to checking the quantity according to the detailed list, and checking the appearance sense, geometric dimension and qualification certificate, we also checked the following data: 

    ① Retest sheet of steel material (original); 

    ② Material certificate of steel (the copy shall be sealed with the official seal of the production unit, and the storage place of the original shall also be indicated);

    ③ NDT report (original).

    (2) Quality control of steel component installation.During the installation of columns and beams, we mainly check whether the sizing block under the column base plate is padded and leveled, whether the column is vertical and displaced, whether the beam is vertical, straight, laterally bent, whether the bolts are tightened and whether the friction surface is cleaned. After the acceptance, the lifting can be carried out.When the steel structure is installed to form a space fixed unit, and the acceptance is qualified, the construction unit is required to use the expansion concrete to pour the space of the column base plate and the top surface of the foundation twice.

    (3) Bolt installation quality control.In steel structure engineering, high-strength bolts and common bolts are generally used for bolt connection. Each bolt end shall not be padded with more than 2 washers, bolt holes shall not be expanded by gas cutting, and exposed threads after bolt tightening shall not be less than 2 pitches. Before using high-strength bolts, we check the bolt certificate and retest sheet. During installation, the contact surface of the plate stack shall be flat and the contact surface must be large.At 75%, the edge gap shall not be greater than 0.8mm, and the high-strength bolt shall be penetrated freely, and shall not be knocked or enlarged; the high-strength bolt shall not be used as a temporary installation bolt, and the bolt shall be tightened in one direction. The final tightening of the installed bolt on the same day shall be completed, and the final tightening shall be checked one by one, and the under tightening and over tightening shall be supplemented or replaced.

    (4) Control of welding quality.Before the welding of steel structure, the qualification certificate of welding rod shall be inspected. The welding rod shall be used according to the requirements of the instruction manual. The weld surface shall be free of cracks and weld beading. The first and second welds shall be free of porosity, slag inclusion and crater cracks. The first level welds shall be free of undercut, incomplete welding and other defects. The first and second level welds shall be subject to non-destructive testing as required. The welder’s steel seal shall be inspected at the specified welds and positions.Unqualified welds shall not be treated without authorization, and the modified process shall be determined before treatment. The number of weld repair for the same part shall not exceed 2 times.

    (5) Quality control of painting works.Before steel structure painting, the painted component surface shall be free of welding slag, oil, water, burr and other foreign matters, and the number and thickness of painting sides shall meet the design requirements.