Welding issues
Thread Content
Currently, a hot air heat exchanger is being manufactured, with the upper and lower tube sheets having different thicknesses: 20 mm for the upper tube sheet and 30 mm for the lower one. The nominal diameter is 1500 mm, and the heat exchange tubes are of 38X3 specification. There is disagreement regarding the welding method for these tubes. One view is that the same welding method should be used for both the upper and lower tube sheets, namely TIG welding. Another view suggests using TIG welding for the upper tube sheet, while for the lower tube sheet, TIG welding should be used as a base layer followed by manual welding for the final coating. Please discuss which view is correct and why Thank you all!
The upper tube sheet is welded using TIG welding, while the lower tube sheet is first welded with TIG welding as a base layer and then finished with manual welding; this approach seems correct! It’s more reasonable from a welding process perspective!
Could a friend explain in more detail? Can TIG welding be used for both the upper and lower tube sheets? TIG welding corresponds to a full penetration method with a single-sided groove and double-sided formation; is non-destructive testing still required? Thank you all for the discussion! !
If the height requirement for the weld is not high, TIG welding can be used entirely. If the height is greater than 3 mm, it is recommended to use TIG welding for the root pass; manual welding for the cover pass can ensure welding quality while also reducing costs. As for testing, it has nothing to do with the welding method.
Thank you once again for your discussions. We have decided to use TIG welding for the upper tube sheet, TIG welding as a base layer followed by manual welding for the finish layer, and to conduct PT testing!