Will welding on an in-service pipeline burn through it?
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It’s a DN250 pipeline that is still in use; the wall thickness is likely between 5 and 6, with a minimum of 4 – I can’t remember exactly. Due to corrosion and erosion, a leakage occurred at a location where it wasn’t possible to make repairs. The leak was quite severe. Initially, the leakage was brought under control by using pressure-based sealing methods, but since the location of the defect was problematic, these pressure-based solutions weren’t very reliable. I now want to add a sleeve at the leak location and weld it in, but there is still fluid flowing inside the pipe, with a pressure of around 4 kilograms. Could welding in this condition cause the pipe to be burned through, leading to an even larger leak?
Plugging leaks under pressure and box wrapping (welding) are key strengths of our factory; the key factor here is the experience and skill of the welders. But this also depends on what kind of pipeline it is; pipelines for gasoline and substances with lower boiling points than gasoline generally cannot be welded.
It seems better to replace it; is the medium flammable and explosive?
Technical measures are necessary, and the experience and skill level of the welder are very important.
The medium is actually circulating water, which is still in the main pipe; if the leak is severe, it cannot be sealed off.
1. Circulating water may also contain combustible gases that leak into the heat exchanger, which can lead to an explosion when in contact with an open flame. Our factory ran into this problem several years ago; hydrogen got mixed in. 2. If it’s okay to carry out welding work, first break a wooden peg to block the leak, and then wrap it with a box (by welding).
It’s the circulating water coming out of the heat exchanger. The medium used for heat exchange isn’t a problem at all – it’s non-flammable, non-combustible, and doesn’t explode, so there’s no need to worry about that. The leaks have been mostly sealed up now, so it shouldn’t affect welding. The only concern is that during the welding of the casing, the pipes might get punctured. Although it’s just water, significant leaks can still cause problems. I originally didn’t intend to take that risk, but my superiors insisted on doing it this way. Well, I guess I have no choice but to wait a few days and see what happens. I hope the welder has excellent skills and can handle this task properly
Even if the fluid medium meets the conditions for open-flame welding, it still depends on the welder’s experience and skills. Safety first! ! !
It’s no big deal. Professional welders: Prepare plans and implement supervision measures
It’s not a big problem; it can be welded, making sure that the fluid inside the pipe continues to flow during the welding process.