Master the most important knowledge of steel structure welding

1. The matching of welding materials such as welding rods, welding wires, fluxes, electroslag welding nozzles and base materials should meet the design requirements and the requirements of the current national industry standard "Technical Specification for Welding of Building Steel Structures" JGJ81. Before use, welding rods, fluxes, flux-cored welding wires, welding tips, etc. should be baked and stored in accordance with their product manuals and welding process documents.

Note: Welding materials have a significant impact on the quality of steel structure welding projects. Its selection must meet the requirements of design documents and current national standards. For the welding materials that have been accepted and accepted when entering the site, the production date, storage state, and baking of the product also directly affect the welding quality. This article stipulates the requirements for the selection and use of welding rods, and especially emphasizes the baking state, which is a necessary means to ensure the quality of welding.

2. Welders must pass the examination and obtain a certificate. Licensed welders must perform welding within their qualified items in the examination and within the scope of their approval.

Note: In the construction and welding of steel structures, welders are a special type of work. The welder's operating skills and qualifications play a role in ensuring the quality of the project, and we must pay full attention to it. The welders referred to in this article include manual welders and mechanical welders. Welders who are engaged in welding construction of steel structures shall, according to the specific types of steel structure welding projects they are engaged in, test the welders and obtain corresponding certificates in accordance with the current national industry standard "Technical Specification for Welding of Building Steel Structures" JGJ81 and other technical regulations. .

3. The construction unit shall perform welding procedure qualification for the steel, welding materials, welding method, post-weld heat treatment, etc. it uses for the first time, and shall determine the welding procedure according to the qualification report.

Note: It is impossible for the welded joints and welded joints in steel structure engineering to conduct on-site physical sampling inspection, and flaw detection can only determine the geometric defects of the welds, and cannot determine the physical and chemical properties of the joints. In order to ensure the welding quality of the project, the welding process specification must be carried out in the construction of component production and structural installation. This article stipulates the conditions for the construction enterprise to perform process evaluation. The construction unit shall perform the corresponding process evaluation according to the type of steel structure undertaken and the specific provisions in the current national industry standard "Technical Specification for Welding of Building Steel Structures" JGJ81 and other technical regulations.

4. The first and second level welds that require full penetration in the design shall be inspected for internal defects by ultrasonic flaw detection. When ultrasonic flaw detection cannot judge the flaws, radiographic flaw detection shall be used. The internal flaw classification and flaw detection methods shall comply with the current national standards. Provisions.

Note: The specification requires 100% inspection of the first-level welds with full penetration, and the partial inspection of the second-level welds is determined as sampling inspection. Steel structure production is generally long, and each weld is inspected according to the specified percentage, and the requirement that each place is not less than 200mm is beneficial to ensuring the quality of each weld. However, steel structure installation welds are generally not long. Most of the welds are beam-column connection welds. The length of each weld is mostly between 250-300mm. It is feasible to use the number of welds to count and sample.