Negative thickness deviation of Q235B steel plates
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When the SW6 software package calculates the strength, a negative deviation of 0.3 mm is assumed for the thickness of Q235B material. Is there a new regulation stating that for Q235B steel used in pressure vessels, the negative deviation tolerance for the steel plates should be 0.3?
According to the original standard, 3274 should be greater than 0.3; check if the value in your material sheet is below 0.3
Is there a value for negative thickness deviation on the quality certificate?
According to standards 3274 and 709, a value greater than 8 mm should correspond to 0.8; check whether the actual thickness you measured is less than 0.3
My question is that the default negative thickness deviation for the SW6 software is currently 0.3; I also think that the negative deviation should be more than 0.3
It’s a software error; my Q235B negative deviation is also 0.3. The negative deviation can be set to zero, and then the standard value for negative deviation can be entered, with that value added to the corrosion allowance. I couldn’t find any setting for a negative deviation in the material database, so I’m not sure how to set it. In fact, Q235B steel plates are no longer considered suitable for use in pressure vessels; grades 150 and above have been listed in the appendix, but people still use them anyway.