Reasons for damage to the U-tube of steam heaters and troubleshooting methods
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I’ve encountered several projects in which the straight sections of the steam heater’s U-tubes (made of austenitic stainless steel, including grades 304, 308, and 321) have suffered damage near the U-bend. I’m seeking expert analysis to determine the causes of this damage as well as any preventive measures that can be taken.
Damage to the straight sections near the elbow area is usually caused by damage incurred during manufacturing, as well as inadequate solution treatment. The preventive measure is to have the factory control manufacturing quality
Another situation is vibration caused by rough processing and manufacturing at the ends.
Thank you for the advice. I still have a question: do you mean that the bent pipe needs to undergo solution treatment after being bent? Was the solid solution treatment of the raw materials not carried out properly?
Yes, when the pipe is bent, changes in the radius of curvature cause the material lattice on the pipe’s surface to become distorted, leading to lattice defects. Some grains are stretched or broken, which results in the precipitation of carbides, a decrease in corrosion resistance, and a reduction in the tensile strength of the steel pipe. Recrystallization can repair defects after solution treatment.