Issues regarding the welding procedure qualification for tube and sheet joints
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Based on the discussions by those who are more experienced in this field, I realize that my understanding of the standards is once again incorrect. Looking at the scope in Appendix D of NBT47014, as per the corrections, it now states: applicable to welds that combine strength welding with expansion welding for the connection between tube sheets and heat exchange tubes. So there are two questions: 1. How to evaluate those that are only welded by strength welding? Refer to Appendix D? 2. Appendix D only specifies the evaluation coverage ranges for pipe diameter and wall thickness. Is there any specification regarding the coverage range for tube sheet thickness? For example, in the case of a tube sheet made of stainless steel composite material (with a stainless steel layer of 2 mm), how should the evaluation coverage range be determined? Or should the evaluation be carried out based on the actual dimensions? 3. How are detailed specifications established for welding a stainless steel layer?
This post was last edited by niat8888 on 2015-7-9 at 12:22. The standards for this thing are written so confusingly that even we find it hard to understand. I’ve never done this before; I only have a basic understanding of it, so I’m not entirely sure if what I’m doing is correct: 1. How should one evaluate welds that are subjected only to strength testing? Based on the main text: 2. Appendix D only specifies the evaluation ranges for pipe diameter and wall thickness; is there any specification regarding the evaluation range for plate thickness? For example, in the case of a stainless steel composite plate with a stainless steel layer of 2 mm, how should the evaluation range be determined? Or should the evaluation be carried out based on the actual dimensions? Refer to Appendix D, D.2; it can be evaluated as a fillet weld. When evaluating fillet welds, the thickness of the tube sheet does not matter. 3. What are the specific requirements regarding the stainless steel overlay layer? Read the chapter on corrosion-resistant surfacing
We don’t quite understand this issue; it needs to be discussed. Our current practice is to use only strength welding for the connection between the tube sheet and the heat exchange tubes, without employing expansion welding; the evaluation criteria for butt welds are applied in this case.