The issue of repairing dented containers
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A custom tank that is 3 meters tall, 2 meters in diameter, and has a wall thickness of 3 millimeters was evacuated, resulting in a depression of more than 1 square meter in the center with a depth of 0.4 meters. Some say it’s sufficient to go straight into the tank and flatten it, while others suggest using 1 kilogram of compressed air to blow it back into shape. I’m not sure which method is better? Experts who work with equipment, please give me some advice!
I think using water pressure is better; first fill the tank with water, then apply pressure with a manual pressure testing pump, which allows for effective control of the pressure applied. The thing to note is: when filling the tank, it should be completely filled, and all air must be removed. This post was last edited by Z1X2H3 on 2009-4-16 13:44.]
LZ didn’t clarify the shape of the upper cover and the lower base; moreover, where exactly is the so-called “middle”? Is it the “middle” of the cylinder or the “middle” of the upper cover? If both the upper cover and the lower base are flat plates, the inflation and flushing methods should be used with caution. Manual mechanical repair is the best option.
Based on experience, the head of a vacuum tank should be an elliptical head; if it is a flat head, its thickness should be **greater than that of the cylinder wall, so the possibility of the head collapsing is very low. The collapse of the cylinder should be of a typical multi-lobed shape, which is mainly due to insufficient design stiffness. After repair, angle steel or channel steel should be used to add a hoop around the cylinder in order to increase its stiffness and prevent the collapse issue from occurring again.
A few years ago we encountered the same problem; we used mechanical repair methods, but they didn’t work. What was mentioned on the second floor hasn’t been tried yet, so it’s not clear whether it will work or not. I hope some expert can come up with a good solution.
Agree with the 3rd floor. It is not possible to apply pressure directly using air pressure or water pressure, as that would cause excessive stress on other parts; plastic deformation might occur, and in that case the entire tank would be ruined. It must be corrected using manual mechanical methods. With a diameter of 2 meters and a wall thickness of only 3 mm, it is clear that stiffness was not taken into account during the design. In addition to adding braces outside as mentioned on the 4th floor, I think it is necessary to add supports inside the tank. Adding a hoop outside is not recommended. I’ve encountered tanks with a diameter of 15 meters before; the water pressure there is very high, and adding supports inside to hold it in place proved to be very effective.
The method mentioned on the 2nd floor works; when filling with water to apply pressure, it is necessary to do so slowly.
Personally, I agree with mechanical repair, along with local heat treatment. The outside of the equipment can be reinforced with angle steel rings to prevent it from collapsing again
Our factory manufactures pressure vessels, and small dents appear on the caps. The designed thickness of these caps is 18 mm; the thickness of the caps after pressing is 19.3–20 mm in our case. The supervisor refuses to allow us to carry out repair welding or MT testing, but the effective thickness of the caps is at least 19.3 mm, so there should be no problem.
The wall thickness is 3 millimeters; there are many simple ways to address this issue. I’m not sure what the design pressure is What are the requirements?
With an inner diameter of 2m and a wall thickness of only 3mm, the pressure that can be applied is very low; it is not recommended to use internal pressure methods for rounding. Personally, I suggest performing manual rounding and then adding reinforcing rings to the outer surface.