ASME Section VIII - Thick Cylinder
ASME Section VIII - Thick Cylinder
(OP)
Good morning, all. I am designing a pressure vessel per ASME VIII Div. 1 and have come to a snag. Page 19 UG-27(c)(1) states that when the thickness does not exceed one-half the inside radius, or P does not exceed 0.385SE use this formula.
My shell will be seamless in nature. The pressure will be 10,000 psi using a 20,000 max. stress material.
ID = 16 so R =8
t=(10,000*8)/(20,000*1-0.6*10,000) -> t = 5.71429 minimum wall thickness. This exceeds one half the inside radius, (8/2 = 4) and also exceeds 0.385*20,000SE.
UG-27(c)(2) is for the longitudinal stresses which has an endnote (20) "20 These formulas will govern only when the circumferential joint efficiency is less than one‐half the longitudinal joint
efficiency, or when the effect of supplementary loadings (UG-22) causing longitudinal bending or tension in conjunction
with internal pressure is being investigated." (Correct me if I am wrong, but without the endnote in play, my welds would be considered circumferential joints and have to use this formula.)
So because UG-27(c)(1) does not apply to my case (wall thickness of 5.71429 > 0.5*inside radius), I then go to Mandatory Appendix 1(1-2)
This is the part that gets me. The welds I have to make would be girth welds being that the material is seamless to attach the end caps. Would these fall under Appendix 1 1-2(a)(2) because of the lack of the endnote? It makes sense to me that these welds are circumferential joints to attach the caps. It confuses me because in UG-27(c)(1) you would think to use the circumferential joints (longitudinal stress) but you don't because of that end note (20).
I do see that Appendix 1 1-2(a)(2) has the extra part of "or when P exceeds 1.25SE". It does not (10000<1.25*20,000*1). It looks like I could technically use either. Am I missing something here?
My shell will be seamless in nature. The pressure will be 10,000 psi using a 20,000 max. stress material.
ID = 16 so R =8
t=(10,000*8)/(20,000*1-0.6*10,000) -> t = 5.71429 minimum wall thickness. This exceeds one half the inside radius, (8/2 = 4) and also exceeds 0.385*20,000SE.
UG-27(c)(2) is for the longitudinal stresses which has an endnote (20) "20 These formulas will govern only when the circumferential joint efficiency is less than one‐half the longitudinal joint
efficiency, or when the effect of supplementary loadings (UG-22) causing longitudinal bending or tension in conjunction
with internal pressure is being investigated." (Correct me if I am wrong, but without the endnote in play, my welds would be considered circumferential joints and have to use this formula.)
So because UG-27(c)(1) does not apply to my case (wall thickness of 5.71429 > 0.5*inside radius), I then go to Mandatory Appendix 1(1-2)
This is the part that gets me. The welds I have to make would be girth welds being that the material is seamless to attach the end caps. Would these fall under Appendix 1 1-2(a)(2) because of the lack of the endnote? It makes sense to me that these welds are circumferential joints to attach the caps. It confuses me because in UG-27(c)(1) you would think to use the circumferential joints (longitudinal stress) but you don't because of that end note (20).
I do see that Appendix 1 1-2(a)(2) has the extra part of "or when P exceeds 1.25SE". It does not (10000<1.25*20,000*1). It looks like I could technically use either. Am I missing something here?





RE: ASME Section VIII - Thick Cylinder
If someone suggests ASME Section VIII, Division 2, I would remind them of 1.2.2.2
May I recommend ASME Section VIII, Division 3.
RE: ASME Section VIII - Thick Cylinder
Our customer has already rejected the idea of going another route such as API, but assuming the AI does reject our 15k psi vessel proposal, I don't guess we could design it per Div. 3 and build it without the U3 license?
See attachment for code case.
RE: ASME Section VIII - Thick Cylinder
Yup, building to VIII-3 without a U3 stamp is problematic
RE: ASME Section VIII - Thick Cylinder
RE: ASME Section VIII - Thick Cylinder
RE: ASME Section VIII - Thick Cylinder
RE: ASME Section VIII - Thick Cylinder