ASME VIII Div1 UG-45(b)(4): Is it a trick to use standard?

[PRTG]

According to the description in UG-45, it seems that there's no possibility of using ANSI/ASME B36-10 lower than schedule Standard (when vessel is under medium pressure, so as that UG-45 (b) (1) to (3) don't apply).

It's no easy to accept it when minium wall thikness by UG-45(a) is very much thinner.

Besides, when using corrosion allowance, no matter how much, UG-45(b)(4) doesn't work even with standard, and we are forced to use ch80 (in small tubes).

I think I'm understanding it well, but it has no sense for me to impose so much material.

Finally, UG-45 is to be used in any case of desinging openings with inserted tubes? Are there any exception because of size of the tube as in UG-36(c3)?


Thanks a lot.

 

[deanc]

See Interpretation VIII-1-83-199

Use with caution.

 

[PRTG]

Thanks deanc but, unfortunately, I haven't at my disposal Interpretations before 07/01 (Vol. 48).

 

[jamesl]

PRTG:
VIII-1-83-199 will not solve your problem. It stated that pipe thickness could be smaller than standard pipe thickness plus corrosion if UG-45 (b) (1) to (3)gave you smaller value.