Number of heat treatment cycles for hydrogenation reactor nozzle welding
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Dear friends, there is a hydrogenation reactor made of 2.25Cr-1Mo material. Due to operational issues during the welding of the connections, it had to be revised three times, which means it underwent three heat treatments. The specifications allow for a maximum of three heat treatments; one more heat treatment is still required. I would appreciate it if experienced colleagues could advise me on whether a fourth heat treatment is possible, and whether the mechanical properties of the material will change as a result of such treatment Is the change an increase or a decrease in intensity? Does it affect quality?
There are two points that are not clear; please explain, OP: 1. Generally, heat treatment is carried out only after non-destructive testing shows satisfactory results. Why is heat treatment still applied during each revision even when the test results are unsatisfactory? 2. Which specification states that only three heat treatments are allowed?
If the heat treatment process is done properly, there should be no problem. I’m not sure which standard states that heat treatment cannot be carried out more than 3 times It has been repaired 3 times; according to the quality standards, your welding procedures seem to be rather poor
Multiple heat treatments can lead to a decrease in strength
To friends on the 2nd and 3rd floors: Since it is Cr-Mo steel, heat treatment must be carried out immediately after welding. After heat treatment, radiographic inspection is conducted; if the results are unsatisfactory, the defective part is cut off and welded again, followed by further heat treatment and inspection. This process is repeated 3 times. Resulting in more heat treatment cycles than required
You can check the simulated post-weld heat treatment time specified in the purchasing specifications for the 2.25Cr-1Mo material you purchase; if this heat treatment time is not exceeded, then the mechanical properties of the material will not be reduced.
This just indicates that three heat treatments were carried out. I would like to ask the original poster: does that standard specify that the maximum number of heat treatments is three?
Return to floor 7; it is required by technical specifications, and the API also has similar requirements for Cr-Mo steel.
Could an experienced friend help explain why it cannot exceed 3 times, and what are the hazards of exceeding that limit?
Which standard specifies that Cr-Mo steel requires heat treatment immediately after welding? I think the original poster must be mistaken; for Cr-Mo steel, hydrogen elimination heat treatment is carried out immediately after welding. Its temperature is not high; it is a different concept from stress-relief heat treatment. It will have no effect on the material. The stress-relief heat treatment, which is specified in the technical specifications as not to be performed more than three times, is restricted due to its impact on the material; therefore, multiple applications of stress-relief heat treatment are not allowed. Please, the original poster, take another look to see if what I said is correct.
Some design firms require such heat treatment, but for important equipment like hydrogenation reactors, it is crucial to manage the \"three types of heating\" during manufacturing (preheating, post-heating, and heat treatment); however, no specific requirement is set for three separate heat treatment steps. Excessive heat treatment can have an adverse effect on the metal, and poor control over heat treatment can even have the opposite effect.