Local stress check for Nozzle on Blind Flange

[koplan]

So often, The nozzle located on blind flange need to be analysed the local ctress per WRC.
Have any method to do this...?
Thanks a lot.

 

[TomBarsh]

WRC-107 does not apply to attachments to flat plates (eg: bolted covers, etc). The bulletin provides method of analysis only for attachments to cylindrical and spherical shells.

For analysis of attachments to a flat plate you can perform analysis by hand using principles from theory of elasticity, etc (see "Theory of Plates and Shells" by Timoshenko).

You can also use the FEA-Nozzles feature in COMPRESS to analyze nozzles on bolted covers. This feature was formerly available only at additional cost. It is now part of the basic COMPRESS license.


"Although this forum is monitored by Codeware it is not intended as a venue for technical support and should not be used as the primary means of technical support."

Tom Barsh
Codeware Technical Support

 

[jte]

Of course, this presumes that the bolted cover has been designed, and is not a B16.5 blind flange. If it is, the limits of unreinforced hole size must be adhered to, as well as the opening being dead-center on the blind. If the opening is reinforced, it must be as called for in B16.5. If one chooses not to do so, then the entire blind becomes a designed component, not a standard one, and there's a good chance that it will not be thick enough.

jt

 

[TomBarsh]

Good points. This issue (nozzle in standard blind flange) was discussed earlier in this forum in thread thread1259-161656.

Hartford inspection had an article in the June, 1999 issue of their Pressure Points describing this situation. See

http://www.hsbct.com/uploadedFiles/CTWeb/AllImages/PP-1999-06.pdf.

I just noticed a related Pressure Points article indicating that bolted covers with nozzles must fall under the Section VIII Code boundary. For an interesting discussion, see

http://www.hsbct.com/uploadedFiles/CTWeb/AllImages/PP-2001-11.pdf.

The June, 1999 article leaves one wondering about the case where Table 7 (now Table 6) in ASME B16.5 permits an opening that is larger than the largest openings exempt from reinforcing requirements by UG-36(c)(3)(a). My opinion is that because the blind flange is a standard pressure part accepted by UG-44 then such an opening is acceptable without further investigation for UG-37 since the opening is permitted by B16.5.



"Although this forum is monitored by Codeware it is not intended as a venue for technical support and should not be used as the primary means of technical support."

Tom Barsh
Codeware Technical Support

 

[jte]

Tom-

Good links, thanks! I agree with your view about the blind remaining a standard pressure component as long as the B16.5 limits are met. Thus, Section VIII-1 work is not necessary for this situation. Really, this is no different than if I use a piping tee as a part of my vessel. If I use a 12"x12"x6" B16.9 tee, the 6" branch opening is not subject to UG-37. Similarly, If I use a 16"x10" B16.9 reducer, I would not run VIII-1 conical transition calc's.

jt