The quality control of steel structure processing mainly lies in the whole process tracking inspection control in the manufacturing process, mainly including the following points:

 1、 Steel structure drawing deepening:

 To deepen the design drawings, the structure of steel structure and joint structure should be improved according to the design drawings.This paper analyzes the welding deformation and the mechanical deformation of the structure, and puts forward the treatment measures for the pre deformation of the structure.

 The number, positioning ruler, weight, material and other information of the components shall be noted in detail.To reflect the overall three-dimensional relationship of the project, the main control coordinates and other macro information, so as to facilitate the measurement and control during installation.

 According to the lifting requirements on site, and fully consider the installation deviation, weld shrinkage deformation and other factors, the welding site needs to be welded in the processing plant as far as possible, such as curtain wall embedded parts, operation platform.

 2、 Raw material control of steel structure:

 　　1.Steel: the quality certificate or inspection report issued by the steel plant shall be inspected in detail. The chemical composition, mechanical properties and other quality requirements must meet the provisions of the current national standards.

 According to the steel quality certificate and dimension specification table, check and check the surface quality, thickness and local flatness of the steel. There should be no delamination, slag inclusion and other defects at the steel end or fracture. 

Six key points for quality control of steel structure processing

　　2.Welding materials: the welding materials used must be matched with the steel used in the project. Due to the differences in quality of different production batch numbers, spot check should be carried out in batches according to the requirements.

 The welding rod and flux shall be kept properly and shall not be affected by damp, otherwise, it will not only affect the process performance of the operation, but also adversely affect the physical and chemical properties of the joint.The welding test shall be conducted again after the welding materials are placed for a long time or are affected by damp.

 3、 Steel structure blanking and hole making control:

 Before cutting, the cleanliness and flatness of steel surface, cutting dimension, roughness, perpendicularity, notch depth and groove angle of steel surface shall meet the requirements; the surface of assembly and welding shall be treated.

 Lofting: the assembly of various components and parts, and the assembly of pre assembled components require professional lofting workers to carry out accurate lofting on the machining surface and assembly large template.After setting out, it must be inspected by the inspector to ensure that the geometric dimension and angle of component processing are accurate.

 The drilling template, the connecting plate and the node plate after drilling shall be corresponding to the datum line on the body; the eccentricity of the hole, the offset of the hole distance, the hole distance, the roundness and perpendicularity, the surface quality of the hole wall and the hole edge shall be strictly controlled.In order to ensure the accuracy and quality of drilling, lofting workers must set out and mark out the datum axis and hole center when using die drilling.

 4、 Steel structure assembly control:

 The strength, rigidity and levelness of the working platform and the jig frame as well as the relevant tooling fixture; the dimensions of the detail drawing and special mould; the material, number, size, processing precision, quantity, connection and surface treatment of welding position of parts; datum plane, datum line, cross center line, assembly position line of parts; assembly position, direction, angle, concentricity of parts and components，Perpendicularity, camber, angle of groove, blunt edge and gap, close fitting of backing plate and dislocation of joint; assembly sequence and method, welding shrinkage and machining allowance; size, length, spacing, position and surface quality of positioning welding.

 Component assembly: component assembly refers to spot welding positioning and fixation before submerged arc welding. Before assembly, small materials shall be corrected. Center line and positioning line shall be drawn by lofting personnel. Spot welding and fixation shall be allowed only after passing the inspection, and formal welding shall be allowed after inspection.

 5、 Steel structure rectification:

 Correction: the rectification work runs through the whole process of steel structure fabrication, from pre blanking to blanking, submerged arc welding, assembly manual welding, etc., to ensure that the size, quality and shape of components meet the requirements of the specification, and bending and distortion deformation are strictly controlled. 

Six key points for quality control of steel structure processing

Treatment of friction surface: the end of the connecting friction surface of the component shall be milled with a milling machine, and the friction surface shall be treated by shot blasting machine, and the surface friction degree will produce floating rust under natural conditions.At the same time, the same material and processing method should be used to make the test piece, and the friction coefficient test should be carried out to ensure that the friction coefficient meets the specified requirements.

 Surface treatment of components: the edge processing shall be carried out for the parts, components and components after processing according to the regulations, and the burr, welding slag, welding spatter and dirt shall be removed, and the surface inspection shall be carried out.After the finished products and the surface of the components are cleaned, the surface of the components is derusted by shot blasting machine.

 6、 Finished steel structure inspection

 Drawing number, component number, axis line, zero line, 1m elevation line and other steel seal marks and their direction and position.The total length, section size, curvature, twist, camber, inclination of both ends, diagonal line of plane, groove of site welding, hole spacing and position dimension of installation hole are qualified, appearance quality of component and chamfering of cutting free edge, etc.