reinforcement of openings 2

[chicopee]

Other that the methods outlined on the fired and unfired pressure vessel codes, is there another method to calculate the amount of metal for reinforcement in the shell opening and in the nozzle.

 

[vesselfab]

yes

but not if you want to apply a code stamp

 

[chicopee]

OK, so what is it or what are they?

 

[JoeTank]

The area replacement method is the only one I see in the pressure vessel and tank codes. While the limits of reinforcement rules may vary somewhat, they are based on same principle. The only alternate nmethod I have seen is a finite element analysis, but that is not given as an alternate in any codes. It's sometimes used to evaluate an existing nozzle that is not reinforced per the code.

Joe Tank

 

[JStephen]

Seems like there is an ASME code case that allows less reinforcing to be used, but I haven't dealt with or even seen it.

The API-650 and AWWA D100 tank codes include reinforcing provisions that are generally more liberal (and simpler) than ASME. They're still based on area-replacement, but allow more of the neck to be included, for example.

The codes and standards vary as to the size a nozzle must be before it is reinforced.

 

[nickelkid]

FEA made easy:

http://paulin.com/NozzlePRO.aspx

 

[chicopee]

As one alternative method that I overheard correctly or incorrectly dealt with moment of inertia replacement instead of area replacement. Has anybody heard anything about that?

 

[TGS4]

There's a new method - based on some work that Les Bildy performed. It's contained in the 2007+ Edition of Division 2. It was based on many many FEAs that Mr. Bildy performed. I think that all of his work was published in a WRC Bulletin (or at least is planned to be published as a WRC Bulletin)...

 

[SnTMan]

chicopee, Appendix 1-10 (Sec VIII, Div 1) seems to provide a stress-based method, I am not familiar with it. It is an alternate means intended for "large" nozzles, but maybe it could be used under U-2(g) for other sizes?

Regards,

Mike

 

[vesselguy]

RCHandy,
If he is doing a Div 1 vessel, FEA is not going to help him. He still have to meet the Code calculated value per uG-37 no matter what.

TGS4,
As I recall, the new alternate method you mentioned in the new Div. 2 is only for self-reinforced nozzles. You can't apply that to a nozzle that uses a repad. I think some jurisdictions are still evaluating whether to allow it or not as the method will yeild a much thinner nozzle wall than traditional way. I haven't had a chance to use it yet and this is what I hear from our boilers branch meeting. Others please provide insight if you got some to share on this method.

 

[chicopee]

I made a copy of Les Bildy's article. Only 10 pages of .pdf reading, not bad for bed time reading.
Thanks to all responders

 

[TGS4]

vesselguy - I agree with your assessment of RCHandy's advice.

You are also correct about the method not being useful/useable for repad reinforcement. There is a movement afoot to bring this new method as an alternative/non-mandatory appendix into Div 1.

 

[hcjulien]

Go see the new paragraph 1-9 in the new ASME Section VIII div. 1 edition 2007 addenda 2008