UG-20(f)(2) Requirements

[10000psi]

ASME Section VIII Div.1, UG-20(f)(2) states as below,
The completed vessel shall be hydrostatically tested per UG-99(b) or UG-99(c) or 27-4. Alternatively, the completed vessel may be pneumatically tested in accordance
with 35-6.


Per this paragraph, the Code allows 'pneumatic testing' instead of hydrotesting. However the paragraph referred for pneumatic testing, para 35-6, refers to mass produced vessels. Does it mean that to use UG(20)(f), para 35-6 needs to be met for any vessel or only the mass produced vessel?

 

[TomBarsh]

Code Case # 2055-1 permits use of UG-20(f)(2) exemptions from impact testing when the vessel is pneumatically tested given some restrictions on test pressure, MAWP, and joint thickness. No mention is made that it applies only to mass-produced vessels.

The Code Case does seem to contradict the published rules of the Code. But as this is a Code Case, not a Code Interpretation, that should not be an issue.

 

[TGS4]

I'm not understanding your confusion here. Ug-20(f) states that

Impact testing per UG-84 is not mandatory for pressure vessel materials that satisfy all of the following:

and then has 5 criteria (1) through (5) that ALL must be met.

So, you are trying to exempt impact testing for pressure vessel materials. You have met criteria (1), (3), (4), and (5), and now you are asking about (2)? If you are trying to exempt your material from impact testing, you can only do so if you mass-produced vessel is pneumatically tested. If you are designing a single-design vessel, then 35-6 is not available to you. So, to meet UG-22(f)(2), your vessel MUST be hydrostatically tested in accordance with UG-99(b) or UG-99(c).

TomBarsh points to an appropriate Code Case for non-mass-produced vessels.

 

[10000psi]

Thank you Tom and TGS4.

Code Case 2055 makes it Clear.

In my case, using UG-20(f) exemption is not an option.