Are there two formulas for calculating the nominal wall thickness of pipes?
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The specification gave me T=t+C1+C2+C3+C4, but the calculation formula my boss gave me was T=(t+C2+C3+C4)/(1-C1). The wall thickness calculated using this formula is about 0.2mm higher than the specification. May I ask where this formula comes from and does it comply with the specification? Attached are some examples of wall thicknesses he calculated.
You didn't notice: C1 in the specification is the absolute thickness, but what your leader gave in the table is that C1 is the negative deviation percentage, 0.125=12.5%. The two C1s are not the same concept.
It’s not an absolute thickness, sir. I checked SH/T 3059-2012. The C1 mentioned above refers to the negative deviation of material thickness. Did I understand it wrong?
Does anyone know the nominal wall thickness?
The C1 given by your leader is the negative deviation rate, and your C1 is the negative deviation size. This should not be a fixed value. The negative deviation of each specification should be different. I personally think it is reasonable to use the negative deviation rate.
Thank you, boss. It seems there is a lot of profound knowledge here. I need to study it carefully.
The principles of the formulas in various specifications are the same, but the forms are different. Depending on your data, the pressure and temperature will not be too high. The formulas in the table are reasonable but do not comply with the specifications. In addition, how do you specify the corrosion allowance for carbon steel pipelines?