Method for reworking surface defect on back surface of weld joint of small container

Abstract

The invention relates to the field of welding, aims to solve the problems of high workload, long reworking time consumption and great secondary reworking risks during the reworking of a surface defect on the back surface of a weld joint of a small container, and discloses a method for reworking the surface defect on the back surface of the weld joint of the small container. The method comprises the following steps of determining an observation hole and a welding hole, and finding the surface defect on the back surface of the weld joint; filling protective gas into the small container, and discharging air; bending a tungsten electrode for reworking, performing wire addition-free welding on the surface defect on the back surface of the weld joint by using the tungsten electrode, and observing the welding progress through black glass until the surface defect observed through the observation hole is completely removed; performing appearance inspection again, and finishing the reworking when the surface defect on the back surface of the weld joint is completely removed; when the surface defect on the back surface of the weld joint is not completely removed, refilling the protective gas, and repeating the operation to weld the remaining surface defect on the back surface of the weld joint until the surface defect is reworked. The reworking method is low in workload and secondary reworking risks, short in time consumption, simple and easy to operate.

Description

technical field [0001] The invention relates to the field of welding, in particular to a method for repairing the surface defect on the back of the weld seam on the inner wall of a small container. Background technique [0002] Such as figure 1 The small container shown is a common stainless steel container formed by welding a cylinder 1 and two heads 2 . The outer diameter of the cylinder 1 is 114.3 mm (millimeters), and the wall thickness is 8.56 mm, and the cylinder 1 is provided with three through holes with a diameter of 17.3 mm, wherein the two through holes located on the upper part of the cylinder 1 are respectively 11a and 11b, the through hole located at the lower part of the cylinder 1 is 12 . The sealing head 2 is a hemispherical shell, and the top of the sealing head 2 is provided with a through hole 21 with a diameter of 17.3 mm. The ports at both ends of the cylinder 1 are respectively butted with the circular ports of the two heads 2, and welded together b...

AI Technical Summary

Problems solved by technology

[0005] When repairing, it is necessary to wear through the weld seam at the position where the surface defect is located on the back of the weld seam before performing repair welding. The workload is heavy and the repair time is long

[0006] The corresponding position of the surface defect on the surface of the weld is estimated by visual inspection, which can easily lead to inaccurate grinding positions, which in turn leads to a much larger area of ​​the weld that is ground off than the actual area of ​​the weld with surface defects, thereby increasing the The workload of rework, and the welding length also increases correspondingly during repair welding, which eventually leads to an increase in the risk of secondary repair

When the number of rework increases, that is, the number of welding increases, it will bring the following problems: First, the number of welding increases, and the amount of hydrogen dissolved in the weld metal due to pyrolysis during the welding process increases, which will inevitably lead to The amount of hydrogen diffused to the overheated zone in the welding heat-affected zone also increases, thus burying hidden dangers for the generation of extended cracks (such as cold cracks) in the welding heat-affected zone; secondly, repeated welding can easily lead to The grains in the overheating zone grow larger due to repeated overheating, which leads to uneven microstructure of the weld and a decrease in mechanical properties

It can be seen that after the weld has been repaired many times, even if the VT and RT (Radiographic testing) that is, the appearance inspection and the radiographic inspection are all qualified, and the mechanical test and the metallographic test have no abnormalities, the repeated repair will still affect the weld. The quality is adversely affected, resulting in the service performance and safety performance of the small containers being repaired are not enough to meet the requirements

[0007] To sum up, it can be seen that when using the existing repair method to repair the surface defects on the back of the weld seam of a small container, the workload is heavy, the repair time is long, and the service performance and safety performance of the container are easily affected by multiple repairs

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