How to weld 304 heat exchange tubes and carbon steel sheet plates at a gauge pressure of 22.5 Mpa to ensure no leaks?
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The tube side pressure is 22.5 Mpa, while the shell side pressure is 1.4 Mpa. Moreover, the heat exchange tubes are 304 heat exchange tubes in accordance with GB13296. The tube sheet is carbon steel. The hole spacing is only 5 MM, so the holes are quite dense. May I ask, when welding heat exchange tubes and tube sheets using TIG welding, how many passes are required, and how should it be done (a diagram would be ideal) to ensure no leaks? I beg earnestly
To avoid welding of dissimilar steels and heat treatment, the owner can weld stainless steel on the tube sheet, about 6 mm thick. Strength welding + expansion fitting can be used, or strength welding + slotted expansion fitting (with expansion tests required to determine the expansion amount); however, it is essential to ensure that the calculations are satisfactory and that the welding height meets the requirements specified for strength.
I agree with the approach of strength welding followed by expansion bonding mentioned above. In our factory, we used to follow this procedure: first perform strength welding, with the first pass being a self-fusing weld and the second pass being a weld with added filler material to ensure strength; afterwards, expansion bonding was used to prevent vibrations during operation
Thanks for the reply, buddy. I would like to ask: for the first self-fluxing welding method, is no welding wire added? There are also those with 2 weld passes like this. Since the hole spacing is not large, they are basically stacked in two layers, one on top of the other. Is this acceptable?
Thanks for the reply, buddy. I would like to ask: for the first self-fluxing welding method, is no welding wire added? There are also those with 2 weld passes like this. Since the hole spacing is not large, they are basically stacked in two layers, one on top of the other. Is this acceptable?
There are standard requirements for the layout of the holes in heat exchange tubes. Who designed the heat exchanger at your company? Too small by 5MM? ? ? ?
With a spacing of 5 mm, if it is constructed according to the 151 standard, pipes with a diameter of 14 should be used; the center distance should be set at 19 units. It is basically built in accordance with the 151 standards, so the welding spacing is definitely sufficient. Self-fusion welding essentially involves melting the heat exchange tube so that its metal collapses and fills the fillet weld; thereafter, additional welding wire is applied to the surface to achieve the weld height specified in the drawings.