HOW TO DETERMINE WALL THICKNESS FOR FULLY RADIOGRAPHY AND SPOT RADIOGRAPHY ???

EXAMPLE:-
Design Data
Outside Diameter of Vessel - 24 in
Internal Pressure - 400 psi @ 650 F
Shell: SA-53B Material, seamless pipe S =15000 psi
Head: SA-515 60 Material, seamless 2:1 ellipsidal, S = 15000 psi
No corrosion allowance

I need to determine the required degree of radiographic examination

Required Wall Thickness for SHELL (ASME CODE)

with E= 1 ; t = 0.317 inch (SHELL) E = JOINT EFFICIENCY
with E= 0.85 ; t = 0.372 inch (SHELL)


Required Wall Thickness for HEAD (ASME CODE)

with E= 1 ; t = 0.313 inch (HEAD) E = JOINT EFFICIENCY
with E= 0.85 ; t = 0. 367 inch (HEAD)


Determine the required degree of radiographic examination,
- USING 0.375 inch nominal thicknes pipe (0.328 inch min thickness) and
0.313 min wall head, the head to shell joint is to be FULLY
RADIOGRAPHED according to Code UW-12 (B) ???

Q -When the shell thickness calulated for E=1 is 0.317, how did he get
0.375 inch thickness

- USING 0.500 inch nominal wall thicknes pipe (0.438 inch min thickness)
and 0.375 min wall head, the head to shell joint is to be SPOT
RADIOGRAPHED according to Code UW-12 (B) ???

Q -When the shell thickness calulated for E=0.85 is 0.372, how did he
get 0.500 inch thickness


ref - PV HANDBOOK - MEGYESY

I am not sure what your question is, but let me know if you are familiar with the following code paragraphs......

You have to apply 12.5% pipe mill undertolerance in accordance with UG-16(d) for design calculations. That is why .375" nominal wall effectively becomes .328" and .500" nominal wall effectively becomes .438" Material selection is key, you can custom order material to a minimum thickness but will discover it is sometimes less expensive to go with a more readily available standard nominal wall thickness material and apply the mill undertolerance.

Also, your reference to UW-12(b) is incorrect and should be UW-12(d) which discusses the requirements of UW-11(a)(5)(b) perhaps this is a misprint on somebody's part?

UW-12(d) and UW-11(a)(5)(b) discuss the basis for claiming 100% joint efficiency for calculations involving circumfirential stress by requiring a "quality" shot on the intersecting seam. If no "quality" shot, then 85% efficiency is to be applied for the circumfirential stress calculation.

_________________
A question properly stated is a question half solved.

I have worked on follow PD5500 codes, Hence I am not familiar with ASME codes and the closest I got hands on PV handbook, from where I started learning on ASME codes.

Thanks again- I have understood the decrease in the thickness