The background to the VIII-1 rules is documented in Annex A of WRC Bulletin 528. They were originally developed by Corten using a fracture mechanics basis.
On your question, toughness is not actually a material property as it can vary based on thickness. Thick components tend to have higher...
Often manufacturer's will stamp vessels for the highest calculated MAWP, not the design pressure. What is the relief device set pressure on the vessel? If it is at the design pressure, it may be acceptable to use that to calculate tmin, else the MAWP should be used. If you do base it off the...
As the Code applies to a wide range of vessels with unlimited loading scenarios, the Code does not define Fs and Ms. The designer is expected to use engineering principles to determine the unit forces f1 and f2. The author of the document arbitrarily used Fs and Ms to designate axial force and...
This is simply a strength of materials calculation. As noted in the Code f2 is the axial load per unit width of circumference. The axial load is a combination of the axial force and the bending moment. The first half of the equation is converting the force into force per unit width by...
MrPDes - The shell will have a slightly different thickness for Div. 1 or Div. 2 as the Div. 2 equation is a limit state equation based on maximum shear stress theory. This equation explicitly considers radial stress, whereas the Div. 1 equation is simply hoop stress equation with a lame...
Paragraph (f) of the Code case prohibits the use of Part 5, so you are out of luck on using FEA on the nozzle with a ratio over 1.5.
You probably will not get a lot of benefit using CC2286 it on the shell. You'll get the most benefits on formed heads, cone to cylinder junctions, and nozzles...
TGS4 - The way the Code case is written is that if you design the shell using the Part 4 rules, then you have to design the nozzles in accordance with Part 4, but not the other way around. Take a look at paragraph (d)(1) of the Code case. The Code case doesn't appear to restrict you from using...
It is understood that Div. 1 does not have this limitation, but the Div. 2 rules are different from the Div. 1 rules and therefore have different limitations. This ratio limit of 1.5 is intended to ensure that the rules in 4.5 are accurate/appropriate. Since Div. 1 uses different rules, this...
You need to comply with all the rules of 4.5 if invoking CC2695. This includes the rules of 4.5.2.1. You will need to use the UG-37 area replacement rules for nozzles with a ratio of greater than 1.5.
It does appear you are out of luck.
Perhaps I did not get across my last point well. It was aimed at the actual failure mode rather than the Code rules. The impact test rules are there to ensure that a brittle fracture does not occur. To have a brittle fracture, you need cold enough...
Division 2 does not consider the PWHT to enhance the toughness, but rather to decrease the driving force to cause a fracture (weld residual stress).
I completely agree with your second statement that the shell/welds cannot tell if they are PWHT or not. We have actually used similar wording in...
Division 2 has separate curves for PWHT and non-PWHT. See Figures 3.7 and 3.8 of VIII-2. It has nothing to do with if PWHT is required or not. If your vessel is PWHT, then you use the PWHT curves. If it is not, then use the non-PWHT curves.
The intention of these curves were to explicitly...
Either a stress reduction was used as permitted by UCS-66 or it could have been done wrong. Alternatively, if it was fabricated prior to the introduction of low temperature requirements (1987 Edition of the Code) carbon steels could go down to as low as -20°F prior to requiring impact testing...
