Raw material defects
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The current situation is as follows: the nominal thickness of the steel plate is 12 mm. During the annual inspection, an ultrasonic thickness gauge was used to measure this section, and the thickness in most areas was found to be between 11.6 and 11.7 mm. However, near the longitudinal seam at a distance of 10 mm, there were some areas where the thickness was 7.2 or 8.2 mm. No pits were observed on either the inner or outer surfaces. The ultrasonic detection frequency varies, but by a very small amount. According to the standards, this does not constitute a defect that exceeds the allowable limits; however, measurements taken with a thickness gauge show that the thickness is indeed insufficient. Has anyone in the group encountered this situation? Are there any people from steel plate manufacturing factories who can provide an answer? What kind of defect could it be?
It is likely not a problem with the steel plate itself; rather, it is caused by excessive grinding of the weld edges during the manufacturing process.
If it is used in a corrosive medium, caution is needed, as this is precisely the area affected by the heat from welding, where corrosion occurs very easily. The solution treatment of stainless steel welds is intended to prevent such situations from happening
Both UT.RT tests were conducted, and the levels were within the acceptable range.
There are inherent deviations in steel rolling, usually negative deviations