What are the causes of cracking in the fillet welds between the tube sheet and the shell?
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It started leaking after being used for a little over two months; I’m still trying to figure out why. I suspect there is a problem with the material of the tube sheet; I wonder if any colleagues who have encountered the same issue can help analyze it. Technical exchange on pressure vessels
The main reason is that during welding, the current was too high, the tube sheet was too thick, and the stress between the cylinder and the tube sheet was high; as a result, this seam cracked when we applied pressure. Later, by using multi-pass welding with a low current, no problems occurred. Especially when the tube sheet is thick and the cylinder is thick as well.
Upon inspection, the material was found to be incorrect; it was designed to be made of 304 austenitic stainless steel, but the flange tested as being 201.
Try performing a post-welding solution treatment
Is the weldability of material 201 good, or are there issues with the welding process parameters?
Stainless steel structural components are difficult to dissolve
We found that there are also issues with the operating conditions – it starts and stops intermittently, and the stress caused by temperature differences is significant; therefore, we have decided to build another unit equipped with an expansion joint.
If the materials don’t match and the welding electrodes aren’t used correctly, there will definitely be problems with the weld
Thermal stress should be the main issue; those who talk about welding problems are basically amateurs