Is 100% radiography performed on low-temperature heat exchangers?
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Last edited by May Day Labor Day on 2009-9-9 14:50: Clause b) of Article A4.8.1 in Appendix A of GB151: Although the design temperature of the heat exchanger is greater than or equal to -40 degrees, the thickness of the joints is greater than 25 mm. How should the welding joint here be understood? Does it refer to the thickness of the weld area including the excess height, or rather the thickness of the metal plate at the welded area? The shell is currently 24 mm thick (with a margin added after welding, the thickness should exceed 25 mm), and the design temperature is -30 degrees. Is it necessary to conduct 100% radiographic inspection?
Based on the conditions you mentioned, it is in a marginal state. Special attention must be paid to such a marginal state, as there are many factors at play: manufacturing processes and the secondary rounding of the sheets can cause the design to appear to be below the safe threshold; yet due to these secondary rounding processes and manufacturing considerations, it may still meet the required standards. It is recommended to conduct 100% RT testing.
100% RT insurance – safety first.
This post was last edited by Wen Bing on 2009-9-10 08:54. It was a mistake; it should be the thickness of the base material at the weld site.
For this borderline condition, it is recommended to conduct a 100% test, after all, it is a low-temperature device
-30 is very close to 40. General handling for -40 conditions.
In my personal view, a \"welded joint\" should include the weld bead excess height; in the case described by the original poster, this height should be greater than 25 mm. According to clause b) of item A4.8.1 in Appendix A of GB151, heat treatment is required.