Pipeline Welding Technology and Process
The welding technology and process of the pipe welding machine are as follows:
1. Before welding, the steel number of the welding material must be identified, so as to correctly select the corresponding welding material and determine the appropriate welding process and heat treatment process.
2. Steel, welding rod, welding wire, etc. should have the quality certificate of the manufacturer. Where there is no quality certificate or if there is doubt about its quality, it should be checked and tested according to the batch number. It can be used only after being qualified.
3. The position of the welding joint should avoid the stress concentration area and facilitate welding and heat treatment. Generally, the joint of the pipe welding machine and the socket of the instrument should not be set in the welding seam or the heat-affected zone. The starting point of the head bending is not less than the wall thickness + 15mm, and not less than 25mm and not more than 50mm; the pipe hole of the welded pipe should be avoided as much as possible on the weld, and the pipe hole weld and the heat affected zone of the adjacent weld should be avoided.
4. The groove forms of pipes, pipes, pressure vessels and steel structures should be processed according to the design drawings. If there are no provisions, the groove type and size should be able to ensure welding quality, less filler metal, improve working conditions and easy to operate, reduce welding stress and deformation, and adapt to the principles of flaw detection.
5. The construction process of the pipe welding machine includes four important processes: counterpart assembly, welding, heat treatment and inspection. After this process meets the requirements, the next process is allowed to proceed, otherwise the next process is prohibited from construction.
6. The minimum allowable ambient temperature for pipe welding machine welding is as follows: Carbon steel: -20℃. Low alloy steel, ordinary low alloy steel: -10℃.
7. During the welding process, the interlayer temperature should not be lower than the lower limit of the specified preheating temperature, and not higher than 400℃.
8. It is strictly forbidden to ignite the arc, test current or arbitrarily weld temporary supports on the surface of the workpiece to be welded.
9. The welding process should be completed continuously except for the staged welding required by the process and inspection. If it is forced to be interrupted, measures to prevent cracks (such as post-cooling, slow cooling, heat preservation, etc.) should be taken. When re-welding, it should be carefully checked and confirmed that there are no cracks before continuing welding according to the process requirements.
10. For concealed welds that need to be inspected, other processes can only be carried out after passing the inspection.
11. After welding, the weld should be cleaned up. After passing the self-inspection, the welder's own code stamp or permanent mark should be stamped near the weld.
12. For steels that are prone to delayed cracks, heat treatment should be carried out immediately after welding, otherwise, post-heat treatment should be carried out. The heating range of the post-heat treatment is the same as that of the heat treatment.
