First, the project or the use of more representative forms of welding joint test, to determine the best methods of operation and Welding Electrode Materials, welding procedure test solely responsible for the welding laboratory.
Second, the structural assembly of tacking
1, positioning the assembly before welding, welding groove and the inside and outside the range of 20mm on each side of the oil must be solvent wiping clean, and polished with a hand grinder to remove rust, oxide and other impurities, the exposed surface of base metal welded pieces of metal gloss.
2, positioning welding welding work as welder must hold certification in welding.
3, the assembly quality and meet the technical requirements before drawing positioning welding (such as the need for warm-up before welding the weld, it must be preheated to a temperature required to locate only after welding.), Positioning welding electrodes used (subject to drying dry treatment), the wire must be used when welding seam welding consumables formally consistent positioning of the weld should be filled crater.
4, positioning the weld length is generally 20-50mm, pitch length of 400-600mm, fillet weld leg size no larger than half the size of the design, and should not be greater than 8mm, should be positioned away from the weld seam end 30mm above the design . (Except in exceptional circumstances)
5, the positioning of the weld shall not have cracks, without excessive slag, porosity and other defects, such as welding defects are found, must be thoroughly cleaned, re-tacking.
6, the weld seam intersections and sharp changes in direction at the weld may not have positioning, positioning the weld should be left there for more than 50mm.
Third, the general provisions of welding
1, as this project must be certified welding welder welders and passing the examination should be specially trained (training assessment for this project).
2, as a welder welding should be familiar with the project technical documentation and construction process requirements, and must be strictly in accordance with welding procedure specifications required by the welding parameters, welding sequence, the direction of welding welding.
3, in order to prevent the components in the welding process produced a large amount of deformation, welding pieces must be placed flat, does not allow casual place for welding, and should be strictly in accordance with the provisions of the welding sequence, the direction of welding welding.
4, should be carefully checked before welding welding groove meets the requirements, and should pay the welding groove and near water, oil, rust, oxide and other impurities thoroughly cleaned before welding.
5, preheat and post weld heat requirements, in strict accordance with the provisions of welding preheat temperature, preheat range, after the heat temperature and time to do warm-up before welding, thermal relaxation after cold working. Welding preheat requirements, the lowest level (Road) preheat temperature between a temperature not less than the channel, the highest level of all welds (Road) between the temperature should be ≤ 250 ℃.
6, before welding on scrap board tested by an official before allowing welding current in welding products.
7, the welding power supply ground wire should be fastened with the base metal weldments, to ensure good contact.
8, the arc should be in the arc welding groove boards, or within, does not allow any damage to the workpiece surface, the base metal arc.
9, welding should pay attention to the starting spot weld, solder and weld the end of the joints does not produce welding defects, welding multi-channel multi-layer, each layer (channel) for welding at the joints should be staggered, each After a welded seam, must be slag, spatter and other impurities, clean, and carefully check the weld quality, confirmed that no defects, then under a welding seam. (If it is found defective weld before said, it must be thoroughly cleaned before welding defects allowed to continue welding.)
10, the plate fillet weld, the weld around the ends must be welded corners.
11, the welding "submerged arc welding" is, in principle, allow the cut in the arc welding process. If for some reason in the welding process occurred off the arc, the weld should be 50mm above the plane to end, and where the use of hand-held grinding machine grinding into a gentle slope like to be allowed to continue Welding Electrodes .
12, the welding "arc welding", the required gas flow should be good to debug, and aspirated about half a minute, put a clean air emissions within the pipeline, before allowing welding on weldment.
13, the "arc gouging" clean weld root, the gouging tool to focus on wind, air pressure should ensure that there are 0.39-0.6MPa, and based on carbon rod diameter, thickness tested by weldment current gouging, gouging process should avoid "carbon folder" and "James Jardine" phenomenon. After clean-gouging, shavings must be removed and hand-held grinding machine to gouge exposed metallic luster after polishing to allow welding.
14, the welding is completed, the surface of the slag should weld spatter and other impurities, clean up, carefully check the quality of the weld appearance, and marked at the required mark welders, and turn order tests (including full-time appearance and internal quality check).
15, welded joints when welding defects occur, are not allowed to handle, should be timely analysis to identify the reasons, according to the rework process and the technical staff in the field under the guidance of welding defects before processing.
16, the workpiece on the board and leads arc flame cutting board to remove the application, is strictly prohibited hammer down.