Take a look at the quality control system in Xinjiang steel structure projects

The quality control system in Xinjiang steel structure engineering is the core guarantee to ensure the safety and stability of the building structure and meet the design requirements. It runs through the entire life cycle of project planning, material procurement, processing and manufacturing, on-site installation to completion acceptance. This system is based on current specifications and standards and combined with the actual characteristics of the project to build a multi-level, full-process management and control mechanism. Through the organic combination of technical standards, management processes and responsibility systems, it achieves refined management of steel structure project quality.

1. Quality pre-control in the design stage

The design link is the source of quality control, and it is necessary to focus on the balance between safety and economy of the structural plan. The editor of Urumqi Steel Structure Manufacturer said that the design unit should carry out structural calculations in accordance with the "Steel Structure Design Standard" (GB 50017) and use finite element analysis software to simulate the stress of key nodes to ensure clear load transfer paths and reasonable node structures. For large-span, ultra-high, and heavy-duty steel structure projects, experts need to be organized to conduct special demonstrations, focusing on reviewing the wind vibration resistance, buckling resistance, and seismic performance design. At the same time, the design document should clarify material performance indicators (such as yield strength and elongation requirements of Q355B steel), welding quality level (first-level welds require non-destructive testing) and coating system (matching scheme of primer, intermediate paint and topcoat) to provide a clear technical basis for subsequent construction. When submitting the design, it is necessary to explain the technical difficulties of key processes in detail to the construction unit and supervision unit, such as box column welding deformation control, cast steel node processing accuracy requirements, etc., to avoid quality hazards caused by deviations in communication of design intentions.

2. Quality control of materials entering the site

The quality of raw materials directly determines the safety of steel structure projects in Xinjiang, and a three-level control mechanism of "source control - on-site inspection - sampling inspection" needs to be established. The editor of Urumqi Steel Structure said that when steel enters the site, it must check the factory certificate and material certificate, and take samples according to the furnace batch number. The inspection items include mechanical properties (yield strength, tensile strength, impact toughness) and chemical composition analysis. It is strictly prohibited to use steel with unqualified mechanical properties or defects such as interlayers and cracks. The connection materials (high-strength bolts, welding rods, and welding wires) need to match the properties of the main steel. For example, E50 series welding rods should be used for Q355 steel welding, and the high-strength bolt connection pair should be retested for torque coefficient or pre-tension force. For functional materials such as fire retardant coatings and anti-corrosion coatings, their bonding strength, weather resistance and coating thickness need to be tested to ensure that they meet the design service life requirements.The editor of Urumqi steel structure manufacturer saidMaterials must be stacked and labeled according to classification, and steel should be elevated to prevent moisture and rust to prevent corrosion; welding rods must be dried in accordance with regulations, and unused welding rods must not be re-dried more than twice to prevent improper material management from affecting construction quality.

3. Process control of component processing

The processing of steel structure components in Xinjiang is a key link in quality control, and standardized management needs to be implemented from cutting, welding, assembly, painting and other processes. Material pretreatment should be carried out before unloading, and rust removal by shot blasting should reach Sa2.5 level standard to ensure coating adhesion. When CNC cutting and blanking, it is necessary to control the cutting accuracy (±1mm). CNC cutting and blanking is used for key components such as H-shaped steel flange plates and webs to reduce manual cutting errors. The welding process needs to implement the "Welding Process Assessment - Certification - Process Inspection" system, select the appropriate welding method (such as submerged arc welding, gas shielded welding) according to the steel grade and plate thickness, and prepare a welding process guide (WPS) to clarify the welding current, voltage, welding speed and other parameters. For parts such as T-shaped joints and cross joints that are prone to stress concentration, double-sided groove welding should be used, and post-welding heat and hydrogen elimination treatment should be performed for 24 hours to prevent delayed cracks.The editor of Urumqi steel structure manufacturer saidWhen assembling components, tooling fixtures need to be used for positioning, assembly deviations should be controlled (such as column verticality ≤H/1000 and ≤15mm), and a total station should be used for three-dimensional coordinate detection. Before coating construction, the surface oil stains and floating rust need to be cleaned again. High-pressure airless spraying process is used to ensure that the coating is uniform. The dry film thickness deviation is controlled within the range of -10% to +20% of the design value. The thickness of each coating must be tested after construction. Only after passing the coating can the next process be carried out.

4. Precision control of on-site installation

The installation quality of the steel structure directly affects the overall stability of the structure, and dynamic management needs to be implemented in conjunction with the hoisting plan, measurement control, connection construction and other links. Before installation, a special construction plan should be prepared to clarify the selection of hoisting machinery (such as the lifting performance of crawler cranes and truck cranes), the setting of lifting points and the lifting sequence, and the hoisting stability of large components (such as steel roof trusses and steel columns) should be checked. Measurement control adopts the principle of "overall control, zoned measurement", establishes a high-precision measurement control network, and uses total stations and levels to monitor axis, elevation, and verticality. The verticality deviation of steel column installation must be controlled at H/1000 and ≤10mm, and the cumulative deviation is ≤30mm. When constructing high-strength bolt connections, the sequence of "initial tightening - re-tightening - final tightening" should be followed. The final tightening torque value needs to be calculated and determined based on the design pretension force and bolt specifications. After the final tightening, a mark should be made on the tail of the bolt, and a spot check of the torque should be carried out (spot check ratio is 10%). The installation of roof and wall purlins needs to control the spacing deviation (±5mm) and elevation deviation (±10mm) to ensure the installation accuracy of the enclosure system. For large-span steel structures, it is necessary to conduct simulation analysis of the construction process, monitor structural deformation, and set up temporary supports when necessary to prevent instability during the construction phase.

5. Inspection, acceptance and quality traceability

The acceptance of steel structure projects in Xinjiang implements a three-level system of "item acceptance - branch acceptance - completion acceptance". Each process must be accepted by the supervision unit before entering the next process. The key points for acceptance of sub-projects include: non-destructive testing of welded joints (UT testing for first-level welds, UT testing for second-level welds: 20%), torque testing of high-strength bolt connections, component size deviations (such as column length deviation ±3mm), coating thickness testing, etc. The acceptance of sub-projects requires verification of sub-project acceptance records, concealed project acceptance records and functional test reports (such as anti-slip coefficient test, fire-retardant coating fire resistance limit test). During completion acceptance, complete quality control information must be submitted, including material certificates, inspection reports, construction records, weld inspection reports, etc., and structural safety assessment must be conducted to ensure compliance with the requirements of the "Steel Structure Engineering Construction Quality Acceptance Standard" (GB 50205). At the same time, a quality traceability system was established, using BIM technology to digitally manage the entire process of component processing and installation, recording the material information, processing personnel, inspection records and other data of each component to achieve traceability of quality issues.

6. Prevention and correction of quality problems

For common quality problems in steel structure projects (such as welding deformation, bolt connection failure, coating peeling, etc.), prevention mechanisms and emergency response plans need to be established. Anti-deformation method and rigid fixation method can be used to prevent welding deformation. After welding, aging treatment or mechanical correction can be performed. The corrected steel surface should not have obvious dents or damage. Bolt connection failure is often caused by improper torque control or incomplete contact surface treatment. Torque wrench calibration needs to be strengthened during construction (calibration is done every six months), and the contact surface needs to be sandblasted to achieve the anti-slip coefficient required by the design.The editor of Urumqi steel structure manufacturer saidThe problem of coating peeling requires strict control of surface treatment quality and coating environment (temperature 5~38°C, relative humidity ≤85%), and coating defects must be repaired in a timely manner. For existing quality problems, technical personnel should be organized to analyze the causes and formulate rectification plans. For example, internal defects in the welds need to be removed by carbon arc gouging and then re-welded. Only after passing the inspection can they be accepted to ensure closed-loop processing of quality problems.

The effective operation of Xinjiang's steel structure engineering quality control system requires a sound management system, advanced technical means and strict responsibility implementation. Through full-process quality control, it can not only ensure the safety of the project structure, but also improve the durability and economy of steel structure buildings, providing solid support for the high-quality development of construction projects. In practical applications, quality control measures need to be continuously optimized based on the characteristics of the project to promote the continuous improvement of the quality level of steel structure projects.