Dapeng Town Industrial Park, Tongshan District, Xuzhou City, Jiangsu Province, China
To prevent the accident of steel structure, it is necessary to carry out strict quality control on the fabrication of steel structure, welding, connection of high-strength bolts, installation, anti-corrosion and so on.
1.Quality control during steel structure fabrication mainly includes.
(1) The yield strength, tensile strength, elongation, section shrinkage and limit content of sulfur, phosphorus and other harmful elements of steel should be guaranteed, and the limit content of carbon should also be guaranteed for welded structure, and the cold bending test should be guaranteed to be qualified if necessary.
(2) To strictly control the quality of steel cutting, cutting should be cleared before the cutting area of rust, oil, after cutting the fracture shall not have cracks and greater than 1.0mm of the lack of prongs, and should be removed from the edge of the fusion tumor, spatter and burrs.
(3) To observe and check the appearance of the component, to the front of the component without obvious concave surface and damage to the qualified
(4) A variety of structural components assembled on the top of the tight surface tightly not less than 75%, and the edge of the largest gap does not exceed 0.8mm.
(5) The production deviation of the components shall conform to the Standard for Quality Inspection and Evaluation of Construction and Installation Works.
2.Quality control of steel structure welding mainly includes.
(1) Welding rod, flux and protective gas used for welding must meet the design requirements and special provisions for steel structure welding.
(2) The welder must be qualified by examination and obtain the certificate of corresponding welding conditions.
(3) The weld that bears tension or pressure and requires equal strength with the base material must be inspected by ultrasonic and X-ray flaw detection in accordance with the relevant national regulations.
(4) The surface of the weld is strictly prohibited cracks, slag, weld tumor, arc crater, pinhole and fusion spatter and other defects. Pneumatic holes and biting edges must be in accordance with the provisions of the construction specification.
(5) The appearance of the weld should be quality inspection, the requirements of the weld wave is more average, the obvious place of welding slag and spatter should be removed. The deviation of weld size and inspection method should be in accordance with the specification.
3.Quality control of high strength bolt connection of steel structure mainly includes.
(1) The type, specification and technical conditions of high-strength bolts must meet the design requirements and relevant standards. High-strength bolts must be tested to determine the torque coefficient or double-check the pre-tension of bolts. When the result is in line with the special provisions of high-strength bolts for steel structure, it is allowed to be used.
(2) The friction coefficient of the connecting surface of the high-strength bolts of the member must meet the design requirements. The surface is strictly prohibited to have oxidized iron skin, burr welding scars and oil contamination.
(3) High-strength bolts must be tightened twice, and the quality of initial and final tightening must be in accordance with the construction specification and the special provisions of high-strength bolts for steel structure.
(4) Appearance requirements of high-strength bolt joints: the direction of bolt penetration is the same on the front side, and the exposed length is not less than 2 buckles.
4.Quality control during steel structure installation mainly includes.
(1)The members must meet the design requirements and construction specification, and the deformation of the members caused by transportation, stacking and lifting must be corrected.
(2) The contact between pad iron and column base and foundation is tight and smooth, and the spot welding is solid. Mortar strength must comply with the provisions.
(3) The center of the member, elevation reference point must comply with the provisions.
(4) The structure appearance surface is clean, no welding scars, oil and mud sand on the large surface of the structure.
(5) Grinding the top of the fastening of the members of the installation surface requirements of the top of the tight surface of not less than 70%, the edge of the maximum gap of not more than 0.8mm.
(6) The promised deviation and checking method of installation shall be executed according to the relevant national norms.
5.Quality control of steel structure anticorrosion treatment should be done.
(1) The type and quality of paint, thinner and hardener must meet the design requirements.
(2) The surface of steel at the base of paint is strictly prohibited to have rust skin, and no welding slag, welding scar, dust, oil and water and other impurities. Check with a spatula by pickling and shot blasting (sand) process of steel surface must reveal the metal color.
(3) Observe and check for misapplication, omission, peeling and reverse rust.
(4) Paint evenly, consistent color, no wrinkles and runoff, clear and neat color separation line
