Jaburantos
Mechanical
- Aug 23, 2021
- 2
Dear all,
I'd like your insight regarding MAWP / wall thickness for pressure vessel and how it should be calculated correctly. Let's say in a hypothetical case, with 0 corrosion allowance, from UG-27, I have calculated required thickness of the shell to be 10 mm. I then ordered plates with nominal thickness of 10 mm. UG-16(c)(2) allows me to use of any plate with actual thickness of 9.7 mm.
For MAWP, knowing that there is a plate with actual thickness of 9.7 mm, do I use 10 mm or 9.7 mm for calculation?
The same question for UG-79(d)(3). Say that for 10 mm required thickness, I ordered plates with nominal thickness of, say, 11 mm. After forming, I found that the thickness is reduced to 10.2 mm near the weld which should still satisfies UG-79(d) point 2 and 3. Which thickness do I use for MAWP, 11 mm or 10.2?
The way I read them, these clauses make it seems like these tolerances are "bonuses", so you can accept / use it and it doesn't have to affect the calculation. I have my doubt because for pipe, UG-16(d) makes it clear that I have to consider mill under tolerance, while for plates, at least for me, not so much.
I'm new to ASME VIII Div.1, so I apologize if the answer is obvious.
Thank you for your help.
I'd like your insight regarding MAWP / wall thickness for pressure vessel and how it should be calculated correctly. Let's say in a hypothetical case, with 0 corrosion allowance, from UG-27, I have calculated required thickness of the shell to be 10 mm. I then ordered plates with nominal thickness of 10 mm. UG-16(c)(2) allows me to use of any plate with actual thickness of 9.7 mm.
For MAWP, knowing that there is a plate with actual thickness of 9.7 mm, do I use 10 mm or 9.7 mm for calculation?
The same question for UG-79(d)(3). Say that for 10 mm required thickness, I ordered plates with nominal thickness of, say, 11 mm. After forming, I found that the thickness is reduced to 10.2 mm near the weld which should still satisfies UG-79(d) point 2 and 3. Which thickness do I use for MAWP, 11 mm or 10.2?
The way I read them, these clauses make it seems like these tolerances are "bonuses", so you can accept / use it and it doesn't have to affect the calculation. I have my doubt because for pipe, UG-16(d) makes it clear that I have to consider mill under tolerance, while for plates, at least for me, not so much.
I'm new to ASME VIII Div.1, so I apologize if the answer is obvious.
Thank you for your help.
