G5 Material Allowable Stresses for Flange Hub Design as per UG-27
G5 Material Allowable Stresses for Flange Hub Design as per UG-27
(OP)
As per ASME Sec. VIII Div. 1 - App. 2 -> 2-1,
"The hub thickness of weld neck flanges designed to this Appendix shall also comply with the minimum thickness requirements in Subsection A of this Division", i.e. small hub thickness (g0) shall be checked as per UG-27.
For flange design we consider lower allowable stresses (of non G5 material).
Now I have following two questions:-
1. Can we consider higher allowable stresses (of G5 material) while checking adequacy of small hub thickness (g0) as per UG-27?
I feel that though being part of flange, hub part is not coming under application defined in note G5 "where slight amounts of distortion can cause leakage or malfunction."
2. Is there any ASME Interpretation / Code Case accepting this?
Thanks.
"The hub thickness of weld neck flanges designed to this Appendix shall also comply with the minimum thickness requirements in Subsection A of this Division", i.e. small hub thickness (g0) shall be checked as per UG-27.
For flange design we consider lower allowable stresses (of non G5 material).
Now I have following two questions:-
1. Can we consider higher allowable stresses (of G5 material) while checking adequacy of small hub thickness (g0) as per UG-27?
I feel that though being part of flange, hub part is not coming under application defined in note G5 "where slight amounts of distortion can cause leakage or malfunction."
2. Is there any ASME Interpretation / Code Case accepting this?
Thanks.
Ashay Kadam
Mechanical Engineer
India.





RE: G5 Material Allowable Stresses for Flange Hub Design as per UG-27
I don't know of any Interp / CC to support thiv view however.
Regards,
Mike
RE: G5 Material Allowable Stresses for Flange Hub Design as per UG-27
You can consider a higher allowable stress for hub portion (operating condition only).
You are right, hub portion is not subjected to distortion causing leakage or malfunction