Shell flange out of roundness 1

[AhmMos]

Dear all,

Shell Body flange. Inner diameter 1232 mm welded to shell side of a reboiler designed as per ASME VIII div 1.
Unfortunately; when we checked the horizontal and the vertical diameters we found that it is 1230 mm and the other 1225 mm respectively, the out of roundness here is 5 mm which is less than 1% as per ASME par UG-80.
Could I assume that this flange is a part of the shell to follow the guidance of UG-80 which mentions tolerance for shell out of roundness.

 

[racookpe1978]

What thickness PV shell, and what pressure is it operating?

Vertical dia = 1225 and horizontal dia = 1230, right? Sag? What does the unit weigh, and how is it supported when measured? (Shell weight, shell thickness, flange weight, thickness and OD = ??)
Are the bolt hole circles able to fit up once lifted into place?

5 mm mis-match is on the ID, which may be only 2.5 mm across the two surfaces. Is this mis-match across a high-flow surface?

 

[r6155]

Out-of-roundess is not the difference between vertical and horizontal diameter; is the difference between the maximum and minimum diameters at any cross section.

Regards
r6155

 

[dhengr]

AhmMos:
As Racookpe1978 suggests, I suspect that a good share of your apparent out-of-roundness has to do with how the tank was/is supported when you took the measurements and the fact that it will naturally deflect under self weight, etc. into something of an elliptical shape, with the longer dimension being the horiz. dia. Rotate the tank 90̊ and 180̊ and see if you get essentially the same dimension differences btwn. horiz. and vert. dia’s. Look in Roark’s book, “Formulas for Stress and Strain,” for starters, there must be some formulas for deflection of a ring or cylinder, standing in a vert. plane. They should give you some feel for what part of the out-of-roundness is due to defection due to self weight. You could also have a bit of out-of-roundness cause by your welding sequencing, but less than 1% wouldn’t seem too bad to me. It should pull-up, fit-up, without much effort when it is finally assembled.