Delayed cracks occurred during the crack repair process of the adsorption tower
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Temperature swing adsorption tower, tower body material Q345R, wall thickness 20mm. The inside of the tower is activated carbon adsorption, the medium is silane-containing hydrogen recovery, half of the tower body is filled with high-temperature water, and the temperature changes from normal temperature to 180°C. Inside-out cracks were found in the tower body. During the repair process, cracks did not appear immediately after welding. Delayed cracks were found in the middle of the weld a few hours later. Please help me analyze the reasons! How to formulate treatment measures?
The half-pipe jacket has a large local stress. I don’t know if there was post-weld heat treatment during the equipment manufacturing. If there is hydrogen sulfide stress corrosion cracking, replace the barrel section.
Temperature difference stress plus hydrogen. I wonder if the stress has been relieved after welding. The design and manufacturing need to be checked.
Are cracks from the inside out penetrating? It feels like "hydrogen embrittlement." You can add a base material and heat-affected zone hardness test in other non-cracked areas to prove it. If the hardness is high, hydrogen embrittlement is very likely.