Material issues in the welding of heat exchanger tube sheets to the shell
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I have a few questions for everyone: For fixed-tube-sheet heat exchangers, 1. If the tube-sheet material is S30408 and the shell-side cylinder material is Q345R, is welding possible? What problems and defects can occur during the welding process? 2. For the important ring welds in this area of the heat exchanger, is it possible to weld dissimilar steels together? 3. If welding is possible, how should the welding electrode and welding method be selected? How to detect it? Thank you! Please also tell me which standards or specifications provide more detailed explanations for the issues mentioned above! Thank you so much! ! !
Welding these two materials poses no problem; the welding rods used are A302 or A302, and they offer excellent welding properties. As for non-destructive testing, it depends on whether the joint is a butt weld or a fillet weld.
This post was last edited by chunyangju on 2015-11-5 at 13:40. Does this consideration relate to the welding of dissimilar steels between the tube sheet and the heat exchange tubes? If so, is cladding the tube sheet an option? You said it is possible; for the specific welding methods and welding materials, you can simply seek support from process evaluation.
The original design of this equipment used carbon steel throughout; however, due to changes in the client’s requirements later on, the process specifications stipulate that the heat exchanger tube sheets and tubes must be made of stainless steel. All other components should remain unchanged in terms of material. So I just consider the case where nothing changes – is that feasible? Is this also a common situation in manufacturing plants?
Thank you! But it’s still a different type of steel! I’ve also asked my friends, especially some experienced colleagues, and they place great emphasis on the consistency of the welding materials used in the heat exchanger area; to date, no one I’ve talked to has encountered a situation like mine. . . . . Generally, they are unified using the same material.
Refer to: NB/T 47015-2011 \"Welding Code for Pressure Vessels\", 4.1.7 b) When welding austenitic high-alloy steel with carbon steel or low-alloy steel, the welding materials selected must ensure the crack resistance and mechanical properties of the weld metal. When the design temperature does not exceed 370°C, stainless steel welding materials with chromium and nickel contents sufficient to ensure that the weld metal remains austenitic are used ； When the design temperature is above 370°C, nickel-based welding materials should be used.
Thank you! In other words, manufacturing in this area can ensure the quality of the weld, right? In this case, with dissimilar steels, is there no problem with welding and inspection when manufactured in this way?
If only the strength of the welded joint is considered, there are no issues with the welding materials or the welding process. S30408 has a relatively high carbon content, and it is prone to sensitization during heating and cooling processes. If resistance to intergranular corrosion is required, it is best not to perform post-weld heat treatment. Austenitic stainless steel is a coarse-grained material, and ultrasonic testing is the best choice for volumetric inspection. Penetrant testing is used for surface inspection.
Welding rod A302 can be used, with shielded metal arc welding being the method of choice.
I’m not from the manufacturing factory, but the factory can only act according to the owner’s requirements. As for the manufacturing plant, there are corresponding process evaluations; just go ahead with it
Welding S30408 with Q345R is very common, and there is nothing special about it. Welding rod A302 is completely fine according to the welding procedures.