Semi-circular pipe equipment cylinder deformation problem
Thread Content
I encountered a difficult problem recently: A stirring kettle, the outer semicircular tube is heated with 160-degree oil, and the pressure is 0.4MPa ； The inner cylinder is evacuated, and the temperature inside the kettle is around 100 degrees. Both cavities are made of S30408 material, of which the semicircular tube is 57 * 3mm, barrel diameter is 1100 * 6mm。 After only a few months of use, all the places covered by the semi-circular pipe (cylinder body, head) have become deformed and concave. According to the strength calculation, the pressure of the semicircular pipe must be nearly 4.0MPa to cause this phenomenon. However, in actual operation, this phenomenon does not seem to occur. Are there any other reasons or factors that may cause this situation? Explain: The semi-circular pipe and cylinder are welded using CO2 protection. It is as follows: https://bbs.hcbbs.com/forum.php?mod=image&aid=2159633&size=300x300&key=02af9d9b330c60e9&nocache=yes&type=fixnonehttps://bbs.hcbbs.com/forum.php?mod=image&aid=2159634&size=300x300&key=9b3ef95ff7ca1b68&nocache=yes&type=fixnone
It is caused by welding stress. Unless the stress is eliminated as a whole, there is nothing we can do.
The same welding method does not occur when the medium in the half pipe is steam. The cauldron is 2300, the wall thickness is 10mm, and the high-temperature heat transfer oil does not have this phenomenon, so it is very strange. . . . . . .
It's just that the inner tube is too thin. As for your calculation, it's haha.
I agree with the 4th floor, it should be caused by welding deformation due to the thin inner cylinder. φ57 * The half pipes of 3 should be relatively dense when arranged, and then deformed greatly when welded. And what I'm curious about is how you agreed to welding with gas shielded welding. All of our units are argon welded, including base and cover. The penetration depth of gas shielded welding seems to be deeper. In addition, the barrel is relatively thin. The layout is dense. . .
The welding stress of stainless steel itself is large. After the half-pipe is welded, the external stress on the middle part of the half-pipe is large. This is not considered in the strength calculation. During use, the stress is superimposed and exceeds the limit, causing deformation.
This material will not deform under this pressure, temperature and thickness. I probably didn't pay attention to it. It appeared when welding the outer coil and it was like this when it was not running.
It's good when it's not used, we noticed
Did you forcefully assemble it when assembling it? Is it deformed due to the stress slowly being released during use?
It is caused by the axial force of the cylinder and the bending stress caused by the internal pressure of the half pipe. It must not be calculated correctly. The thickness of the cylinder wall is small.