Temperature changes in pressure vessels cause weld cracks
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It is a pressure vessel made of Q345R material, with welding rods of type 507. When the vessel was shut down, the temperature dropped from 230 to 150 degrees within one hour, resulting in cracks in the head welds that were 4 mm deep and 2 meters long. The manufacturer attributed this to too rapid a rate of temperature drop. The operating pressure was 1.3 MPa, and the operating temperature was 235°C. Experts, could it really be the rapid temperature drop that caused this issue?
That reason seems a bit far-fetched. Our company has previously designed heat exchangers with an operating temperature of 350°C, and during the commissioning phase they also stopped and started frequently, but nothing went wrong at all
What’s the thickness? This insufficient temperature drop causes weld cracks. External crack or internal crack? What medium?
Send a photo of the full view of the crack (indicate whether it is on the inner or outer surface), as well as the container’s diameter, wall thickness, the medium used, and whether it operates continuously or cyclically.
It is necessary to first understand the technical specifications of the equipment as well as the operational characteristics during use; it’s not sufficient to just state things verbally – it’s important to determine whether the equipment is being used beyond its limits
This reason is a bit far-fetched; it’s just a reason after all. . The key is to ask everyone to work together to analyze the reasons, in order to prevent further complications. .
For a material like Q345, when used within such operating temperature and pressure ranges, the wall thickness is likely to be fairly thin; therefore, cracks are not expected to be caused by shutdowns.
Agreed; if a photo could be attached, we can all analyze it together to see where the problem lies
;P I mean, they should sit down with the manufacturer and discuss things calmly. . . . Instead, I’m asking you – it’s just nitpicking. . If you answer me, it’s just avoidance
I have worked on several projects, and whenever problems arose, the responses from various parties were always driven by their own company’s interests. Even when the reasons given were unfounded, they would not communicate openly for the sake of honesty, out of concern for their own companies’ interests. On the other hand, in forums where there are no such interest conflicts, the analyses tend to be more objective
Temperature changes need to occur over multiple cycles before cracks appear; a single start-stop cycle will not cause cracks – it’s likely a manufacturing issue