Cylinder defect welding repair method

Abstract

The invention discloses a barrel defect welding repair method which can improve the success rate of one-time repair welding and aims at avoiding inner wall repair welding. When repair welding is performed, the repair welding area of a barrel is regulated to the position of ten o'clock to eleven o'clock or the position of one o'clock to two o'clock, and then welding starts to be performed along the weld root near the inner side of the barrel to enable the projection area of the non-repair-welding-area on the barrel cross section to be roughly in the shape of a U; the U-shaped section is remained, and repair welding is completed layer by layer from inside to outside. When every a U-shaped section layer is welded, the welding bead must be overlapped from the thicker wall position to the center in the circumferential direction of the barrel in a symmetrical and circumferential mode, and each circumferential circle of the welding bead is divided into two half circles to complete welding in a climbing mode in the circumferential direction of the barrel. The stress concentration factors of the weld toe can be effectively reduced, welding shrinkage stress is reduced, the stress direction of the weld toe is changed, and therefore repeated cracking in the repair process and repair welding work after removing backing plates can be effectively avoided. The method is particularly suitable for defect repair of the barrel with the wall thickness more than 70 mm.

Description

technical field [0001] The invention relates to the field of welding repair, in particular to a method for repairing defects of a cylindrical body with relatively large wall thickness after manual or automatic welding. Background technique [0002] At present, the header is one of the important parts of the power plant boiler, and generally consists of a cylinder, an end cover, a transition pipe, a pipe seat, and an ear plate. The header cylinder is generally made of large-diameter seamless steel pipes. Due to the long header cylinder, it is inevitable to splice the length of the cylinder in actual production, and welding of the spliced ​​welds is also necessary. In order to ensure the welding quality and improve the welding efficiency, the high-quality and efficient welding method of "submerged arc welding" is mainly used when selecting the welding method of the header cylinder. However, some welding defects will inevitably occur in actual production. Restoration is requir...

AI Technical Summary

Problems solved by technology

Since the defect has a certain length and width, and the depth is different, to completely remove the defect, the thickness direction may be dug through, forming a narrow and long pin-shaped hole, and single-side welding cannot ensure the welding quality of the back side. However, such a header The inner diameter of the component is small, and the preheating temperature before welding is generally above 200°C, the inner wall cannot be welded, so it is very difficult to repair

However, in the actual repair welding process, it was found that the welding toe of the groove surface on one side of the repair welding area in the length direction, that is, the joint between the backing plate and the cylinder, is prone to cracks. After grinding to eliminate the cracks and welding again, cracks are still found

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