Sand holes found in stainless steel
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A 304 stainless steel pipe that had been in use for about 10 years was found to have sand holes; the leakage point was located about 5 millimeters above the weld. The medium flowing through the pipeline is propylene at 10°C and 4.0 MPa, with insulation in place. Could anyone tell me what causes sand holes in this situation? Thank you all.
Thank you for your reply, but this location is about 5-6 mm away from the weld joint. Will welding affect this area?
It’s a problem with the base material, right? I’ve encountered this before: new pipes with a hole in them that leak air.
Thank you; we also think the base material is the issue, but it’s a bit strange that problems only arise after about ten years of operation.
It must have existed all along but wasn’t noticed, right? P
Regarding base material issues, for industrial pipes: 1. They are basically all drawn (seamless pipes); 2. there are also non-standard types that are rolled from stainless steel sheets. If it is the latter type (stainless steel sheets that are rolled into tubes and then welded), then if there are defects such as sand holes in the quality of the stainless steel sheets originally, these defects will become more apparent after the tubes are formed and further processed (such as polished). However, it is not possible to let customers see such defective products at the time of delivery; they are usually polished to a high degree. :)
Is it the same for the position of the solder joint that connects to ground?
Haha, that’s possible too. But in the past, even if there were leaks, they were minimal, as there was a gas detector nearby.
Thank you. This is a 316 seamless tube that is integrated with the valve; it seems likely that it is the base material after all.