Cracks and corrosion occurred when the 316L heat exchanger was not put into use
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A 316L heat exchanger has been left in the open air for ten years. I recently planned to use it, but found that there were corrosion pits and cracks on the welds of the tube sheets and tubes, and there was also pitting inside the tubes. What is the reason? Will the tubes crack?
You should worry more about whether the joints between pipes and tubesheets will leak.
It is estimated that there are material and manufacturing issues, as well as whether there are corrosive gases in the storage location.
The graphite heat exchanger has been used continuously for 10 years under the conditions of 31% hydrochloric acid and 130 degrees, and no corrosion has been seen. -
The factory warehouse is close to the seaside, and the pipe connections between the two sections of pipe boxes are not sealed with blind plates.
Oh, it should be because it is near the seaside and there is a salty smell in the air.
Is it caused by welding stress and seaside air? Is there also a problem with the material?
It should be fine when leaving the factory, but it's been ten years and it's hard to trace. I think it's also SCC caused by chloride ions. What I don't understand is why there isn't one on the other tube plate? Or why are there cracks on just these few pipes?
At the seaside, stress corrosion cracking caused by salt spray. It is an improper storage problem: There should be a dedicated storage rack for the storage of stainless steel profiles. The storage rack should be a wooden or painted carbon steel bracket or padded with a rubber pad to isolate it from other metal materials such as carbon steel. When storing, the storage location should be convenient for lifting and transportation, relatively isolated from other material storage areas, and protective measures should be taken to avoid dust, oil, and rust contaminating stainless steel.
It should be caused by salt spray corrosion. Materials like this are usually stored with nitrogen for protection.