Interpretation VIII-1-01-61

[Jano6924]

Gentlemen:

Interpretation VIII-1-01-61 reads as follows:

Question: A nozzle is located in a shell made of welded pipe for which the allowable stress listed in Section II, Part D has a factor of 0.85 applied. When determining the minimum nozzle neck thickness in accordance with UG-45(b)(1) of Section VIII, Division 1, may allowable stress for the shell material, as listed in Section II, Part D, be divided by 0.85 in order to determine the shell thickness to be used in this paragraph?
Reply: Yes.

My question is:

When calculating the minimum nozzle neck thickness “ta” for internal pressure per UG-45 ¿is it valid to do same thing for the nozzle neck (divide allowable stress by 0.85) IF nozzle neck is made of welded pipe for which the allowable stress listed in Section II, Part D has also a factor of 0.85 applied?

Your comments will be highly appreciated.

 

[XL83NL]

As per this interpretation, I guess the answer is no since it only talks about shell material. Not sure if other code sections, interpretations or code cases do allow the same practice for the nozzle pipe.

Huub
- You never get what you expect, you only get what you inspect.

 

[TGS4]

Your question is not addressed by the interpretation.

If you asked my personal opinion, the answer to your question is "no".

 

[Jano6924]

XL83NL & TGS4:
Thanks for your comments, I really appreciate that.
Best Regards.

 

[GD2]

Jan06924,
I agree with the interpretation.

Allowable stress S value calculated in Table 1A and 1B for welded pipes and tubes already accounts a 0.85 factor, thus reducing the S value for welded pipes.
If we factor the S value by another 0.85 (E) in the thickness equation, it’s a double dip. SE goes together in thickness equations.

Therefore if one uses Tables 1A and 1B, no further reduction in S value is required. This note is missing in the design thickness equations.

The rule is applicable to only 1A and 1B Tables.

GDD
Canada