How to repair a sulfur trioxide pipeline leak?
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One of the pipes we produced through the conversion process had weld leaks; after welding it using A302 and 507 electrodes, pinhole-like leakage points appeared in multiple places, and the more welds were applied to fix these issues, the more cracks formed. I would like to ask how to deal with leakage points, and what type of welding should be used for repairs?
We usually polish it, clean it with alkali, and weld it using 507
It is difficult to weld firmly at high temperatures. It is best to do the cleaning and grinding (creating bevels) at low temperatures, then choose the appropriate welding rod (507, 506, stainless steel); the welder also plays a crucial role in this process. . I’ve learned this many times: with the same materials, different people yield different results. . .
Reply to 2# hotmsn: I didn’t stop working; I was repairing the smoke pipes that had been produced, and the temperature there was very high. I used 507 welding rod as well, but cracks appeared in the welds
Reply to 3# lbylc: What if it doesn’t stop and repair is needed with the material still in place?
Reply to 5# QiuSuo790207: It’s very difficult to perform welding without stopping the machine, and it requires high technical skills. We tried it – setting the air flow to the lowest level is essentially the same as shutting down the machine.
Thank you all. We have fixed it; we need a better welder to finally weld the pipe and install a blind flange.
It’s basically a matter of the welder’s skill; we have no precedent of stopping the machine to weld the flues – we always carry out welding repairs while the machine is running. Pressure welding repairs are a technical task; first of all, the welding rod must be chosen properly – regardless of the material, E309 can be used. Secondly, the key to welding under pressure is the anchor worker’s technique, as it must be welded in a leak-proof manner. Specifically as follows: 1. First, weld reinforcing ribs around the leaking area to secure the flue in that region, preventing further cracking of the flue due to thermal effects. 2. Perform surfacing welding along the edge of the leak; once the edge of the molten pool turns dark red, push it into the area where there is a leak. This way, it won’t be blown away by the smoke. Do this bit by bit until the work is completed. The same method should be used if any sand holes appear. 3. Finally, weld the weld seam and the base metal on the edges together once more. 4. If the leakage area is large and anchoring is not feasible, weld a pipe and install a flanged blind plate.
Reply to 10# szczl123456: The explanation is very detailed, thank you!