This is how to solve the problems of tube sheet and flange welding

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This post was last edited by huanghong on 2022-4-20 09:37 Tube-sheet and flange welding are steel structures. Welding methods commonly seen in pipeline welding mainly include flat welding, tube-sheet horizontal butt welding, oblique 45° butt welding and overhead welding position welding. Today, the editor will explain to you the main operating methods of horizontal tube sheet and flange welding, as well as frequently encountered problems and solutions. The operation method is suitable for tube-sheet extension flanges and steel structure tube-sheet butt joints. 4.0mm J422 welding rod is used. Before welding, ensure that the post-weld position of the tube-sheet butt is polished cleanly. 1. Start the arc from the 6 o'clock position at the bottom of the pipe, and perform swing welding from 6 o'clock to 8 o'clock using the oblique zigzag strip transport method. ； 2. For vertical welding from 8 o'clock to 10 o'clock, use the zigzag method of welding. ； 3. Climb welding from 10 o'clock to 12 o'clock using the elliptical strip transport method. ； In the above three transport methods, the welding hand should be slightly faster in the middle and stop on both sides to ensure the fusion of both sides and prevent the phenomenon of incomplete fusion. 4. During the welding process, always keep the arc short arc welding (lower the arc length), keep the electrode angle at 45°, and maintain a stable arc height and rod transport speed. 5. For cold bead joints, scratch the arc 3-4mm in front of the joint to the arc ignition point, and move the strip in a circle at the moment when the molten pool merges at the groove. Use an oblique zigzag shape to move the strip, which is consistent with the welding operation on the opposite side. Main problems and solutions Problem 1: Some novice welders often have welding beads that go down during welding. The main reasons are that the angle of the welding rod is wrong and the distance between the welding rod and the upper break is too close. Solution: The angle between the welding rod and the tube sheet should be kept at 45°, and the front and rear tilt should be 80-90°. The welding rod should be 1-2mm away from the lower break at the junction of the tube and plate. If there are special requirements for the size of the welding fillet, the welding fillet of 5mm can be used without swinging, and the welding fillet of 6-8mm can be swung in a zigzag manner. Question 2: Solutions to poor connection of connectors: The main focus of the joint is the molten pool. In order to make the joint smooth, the arc should be started about one third above the center of the molten pool at the end of the previous weld bead. Then, after the molten pool is stabilized, a circle is drawn to fill the weld and move forward. Question three: The welding of small diameter tube plates cannot be completed in one pass. This is a common problem among novice welders, which is caused by the inability to change the technique and angle as they walk. Solution: Needs constant practice * , it will get better after you become proficient.