Corrosion problem of heat exchange tubes
Thread Content
We manufactured two tanks with oil-heating coils for a client; both the tank bodies and the tubes were made of S30408 material. One tank was in use for just over 2 months, while the other was used for over 4 months. Cracks and leaks appeared in the welds of the coils as well as in the welds where the tubes were connected to the tank bodies. The composition of the material stored in the tanks was unknown to us, and we believe that chloride ions present in the material, combined with the high temperature of the hot oil, were the cause of the problems. I’m not sure how to explain this to the customer; I’ve turned to experts for advice.
Ask the customer for the material composition; otherwise, how can we analyze it?
Material issue； Weld seam treatment issues ； Stress problems – any of them are possible
One must understand the material composition before being able to analyze it
It could also be caused by a difference between the welding material and the base material. If it is caused by chloride ions combined with high temperatures from hot oil, it will not appear only in the weld area.
It is necessary to understand the composition of the materials in the tube side and shell side, as well as parameters such as temperature and pressure, in order to know. Cracks of this kind, which are merely cracked, are generally due to chloride stress corrosion cracking; they could also be caused by polybisulfate stress corrosion cracking. The wrong material was used.
The inability to provide detailed material compositions is not the responsibility of the design and manufacturing team.
Problems with the weld may be caused by using the wrong welding material or issues with the welding process.
Based on this simple description, it’s quite likely that there is an issue with the welding material; I agree with what was said above.
Poster: Was the welding rod used incorrectly? Or is the welding process incorrect? You mean only the welds of the heat exchange tubes are leaking, right?
Thank you all! Our company specializes in the production of various types of reaction vessels, and other users have had no problems using them. Therefore, we believe that there is no issue with the wrong type of welding rod or improper welding techniques; instead, it seems that the material S30408 was used incorrectly, and corrosion caused this problem (the temperature of the hot oil is over 200 degrees). At first, we asked the user about the composition of the material and what kind of material was being used, and they said that S30408 would be sufficient. I don’t know how to convince users now