Large-area defects in welds of 1.1MPa steam pipelines
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In our facility’s 1.1MPa steam pipeline, with a DN450 diameter, extensive defects were found at the welds of bends such as expansion bends; the surface showed sand holes and leakage issues. However, after grinding, it was discovered that most of these defects were actually cracks, with 3 longitudinal cracks present, one of which reached the flange. I was wondering if anyone has had similar experiences, and how they analyzed and handled them. I would appreciate any advice you could share.
First of all, what is the material of your flange? Is it carbon steel forgings or stainless steel? If cracks appear in the forgings, it might be a problem with the material of the flange – perhaps the carbon content is too high
There is no issue with the material of the flanged 20# steel
This post was last edited by wanlirn on 2021-11-6 at 08:10. Let’s see which construction team is responsible for this work; whether it involves multiple subcontracts, and whether they chose some cheap local crew just to save money, as well as whether they are deliberately underpaying those workers. Ordinary steam pipelines are no challenge at all
The weld defects should be pores and slag inclusions; there are no sand holes, which constitutes a welding quality issue
Trachoma appears in multiple elbows; the material of the elbows is under consideration
General experience is that horizontal cracks are due to material issues, while vertical cracks are caused by welding problems
Steel elbows, unlike cast parts, rarely suffer from sand hole defects
Since I can’t see the photos, based on past experience, if cracks appear beside the weld, in the heat-affected zone of welding, there is likely to be a significant welding issue.
First, analyze whether there is a problem with the steam quality.