Steel Structure Project Construction Plan (4)

(VII) Welding method and welding material requirements

If necessary, the site will set up temporary wind and rain shelters to improve the impact caused by wind, rain and other natural environments.

Select the appropriate welding machine, carbon arc gas planer, voltage regulator and welding auxiliary devices such as drying box, insulation cylinder, etc., to ensure that the equipment required for welding is complete and can meet the needs of quality assurance, welding rod must be dried and processed before welding.

Provide qualified welders and flaw detection engineers, all welders must be licensed to work, all butt welds must be flaw detected, the welding grade should meet the design requirements.

1. Welding method and welding material selection.

According to the location of the project structure welding joints, on-site welding construction using a combination of manual welding method, welding materials according to the material of the structural steel, on-site welding using manual arc welding, welding materials: E4303 or E506 welding electrode, positioning welding with manual arc welding. Priming welding with a diameter of 3.2 welding rod, filler and cover welding with a diameter of 4.0 welding rod. (Such as wet weather, the need for electrode baking) according to the table selection.

2. Structure welding construction sequence.

Welding construction sequence has a great impact on the welding deformation and residual stress after welding, in order to minimize the deformation of the structure after welding and residual stress after welding, structural welding should be implemented as far as possible with symmetrical welding, so that the structure subject to hot spots in the entire plane symmetrical, uniform distribution, to avoid distortion of the structure due to uneven heating and larger residual stress after welding.

3. Welding sequence requirements.

① general principle: any member welding as far as possible to arrange a double number of welders for symmetrical welding, in order to maximize the avoidance of welding stress caused by the deformation of the member, should be applied first to weld the entire structure node priming welding, then welding the entire structure node filler welding, and finally apply the node cover welding, so that the layers of stress have a free release process.

② Before welding, welders are required to check whether the tooling tire frame is effectively positioned on the structural members, whether there are conformal devices at both ends of the structure, and do a good job of wind, rain, insulation and other preparatory work before welding, in the welding process as far as possible using a welding method for welding, in order to reduce the additional welding stress caused by different welding energy.

4. Weld quality inspection requirements.

The project 2 layer beam-column, beam butt weld between the weld for the second level, weld welding 24 hours after the 20% ultrasonic nondestructive flaw detection, the assessment level Ⅲ. Other parts of the weld for the corner weld, three-stage weld, no flaw detection test.

5. Welding process assessment requirements.

① welding process assessment according to the "Code of Construction Quality Acceptance of Steel Construction", according to the "Construction Steel Welding Regulations", technical requirements of the construction drawings.

② welding process assessment before, according to the steel structure project node form of the corresponding welding process assessment guide, used to guide the welding process assessment test (welding process assessment test has been done, the engineering supervisor to confirm the exemption or alternative). After the welding process assessment test is passed by multiple tests or test evaluations, the company's testing center will issue a welding process assessment report based on the test results.

③Before the welding process evaluation, the competent welding engineer shall prepare the welding process evaluation test program according to the content in the "Welding Regulations for Building Steel Structures" and combined with the structural characteristics and node forms of the products.

④Welding process evaluation test program proposed by the competent welding engineer, the owner or the supervisor countersigned the implementation.

⑤ Construction units according to the welding process evaluation report, the preparation of welding process guidance for guiding the welding of products