Simple Vessel Opening Question 3

[Derek57]

Hello,

What does ASME consider a large opening in a pressure vessel? I have a copy of ASME Section VIII Div. 1, and I have read UG-36 and UG-37; does a large opening require reinforcement and a small opening does not (therefore small openings are based upon vessel shell/head thickness)?

If someone could offer an explanation or point me to the correct section of the Code where this is defined I would appreciate it

Thank you for your time.

 

[SnTMan]

Derek57. Code does not generally define an opening as "large" or otherwise. UG-36(b) sets requirements for size of openings.

UG-36(c)(3) permits certain openings to be exempted from reinforcement calculations. Generally, all other openings will need reinforcement calculations performed per UG-37, Appendix 1-7, Appenidx 1-10, etc.

Regards,

Mike

 

[Derek57]

Thanks Mike,

My confusion initially came from Appendix 1-10 which referenced large openings in cylindrical vessels.

I appreciate your help on this matter.

 

[jamesl]

I disagree with SnTman on this one. Although code does not explictly define large opening, it is implied in the code that opening exceeds the limit in UG-36(b)(1) (see below) is a large opening that needs to satisfy Appendix 1-7 which is titled "large opening in cyclinrical and conical shells"

The rules in UG-36 through UG-43 apply to openings not exceeding the following: for vessels 60 in. (1 500 mm) inside diameter and
less, one-half the vessel diameter, but not to exceed 20
in. (500 mm); for vessels over 60 in. (1 500 mm) inside
diameter, one-third the vessel diameter, but not to exceed
40 in. (1 000 mm). For openings exceeding these limits, supplemental rules of 1-7 shall be satisfied in addition to the
rules of this paragraph