How should cracks in pressure vessels be dealt with?
Thread Content
Cracks in pressure vessels: The methods for dealing with cracks in pressure vessels are as follows: Cracks in the base material of the vessel wall (1) Surface and near-surface cracks. Eliminate it using an arc-transition grinding method, and then conduct magnetic particle inspection and re-inspection. (2) Internal cracks. First, ultrasonic testing is used to locate the crack, followed by radiographic testing to determine the exact shape of the crack. Then, the crack is repaired using either a truncation method or a patching method. Treat using truncation. Applicable to single linear cracks. The processing procedure is as follows: the cracked area is cleaned and polished on the surface until the crack is exposed. Then, magnetic particle testing, coloring inspection, radiographic testing, or a magnifying glass are used to determine the direction of the crack, and the two ends of the crack are identified. At a distance of approximately 40–50 mm along the crack from each end, a \"stop hole\" is drilled. When the wall thickness of the component is ≤16 mm, the diameter of the hole is 6–8 mm; when the wall thickness is >16 mm, a hole with a diameter of 6–8 mm is drilled first, after which it is enlarged and repaired by welding. Treat with patching method. It is commonly used for treating star-shaped cracks and branched cracks. The processing procedure is as follows: first, locate the area where the crack is located, then use gas cutting to remove the crack; the area cut out should be 40–50 mm larger on each side than the original crack area. After that, a new plate is installed, or the plate with the crack is replaced entirely. Cracks in the heat-affected zone are generally removed by grinding, and magnetic particle or dye penetrant testing is used to confirm that no cracks remain. For cracks in the weld area, radiographic or ultrasonic testing is used to locate the tips of the cracks; thereafter, stop holes are drilled at both ends of the cracks using the stop method, with the depth of these holes being slightly greater than that of the cracks. The entire crack is then removed, and a suitable bevel is created. After confirming through radiographic testing that the crack has been completely removed, welding is performed to repair the area.
In summary, for dealing with cracks in pressure vessels, it is necessary to first determine the type and location of the cracks, and then select an appropriate treatment method, including grinding, flaw detection, cutting off, or patching. During the processing, it is necessary to ensure that the cracks have been completely eliminated, so as not to affect the safety of the container any longer. .
The author’s article provides a comprehensive overview; in practice, it is necessary to develop a complete and reliable repair procedure based on the specific conditions on site before proceeding with the work.
Equipment worth tens of thousands of yuan can be replaced outright; for particularly expensive equipment, major repairs can be considered. Of course, surface pseudo-cracks can be removed by grinding.
I’ve learned it, and I’ve dealt with a few similar cases as well.