NB/T47014 Appendix D: Welding procedure qualification for heat exchange tubes and tube sheets – separate qualification or combined qualification
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NB/T 47014 Appendix D: Evaluation methods for the welding process assessment of heat exchange tubes and tube sheets: separate assessment, combined assessment. Evaluation is carried out separately as follows: 1. Evaluation of butt welds ； 2. Fillet weld evaluation (additional evaluation). Combined assessment: On the same test piece, the welding procedure assessment for the heat exchange tubes and the tube sheet is carried out together with the additional welding procedure assessment. There is one thing I don’t understand: what is the difference between the separate evaluation of fillet welds and their combined evaluation here? How do they do it respectively?
Personally, I believe it is not necessary to evaluate the butt welds, as long as welding is carried out in accordance with NB/T47015, following the provisions of Appendix D of NB/T47014. The stress on the pipe sheet and heat exchange tubes resulting from welding is minimal and can be practically ignored; it is sufficient to ensure that the weld thickness meets the required standards. However, inspections for issues such as lack of penetration and incomplete fusion should still be conducted in accordance with the inspection requirements outlined in Appendix D.