shell stresses from loads applied to nozzles

[gnow]

In the Pressure Vessel Handbook by Megyesy, there is a method "based in part on WRC 107" outlined to calculate whether given nozzle loadings exceed stress limitations in the shell. The quantity Sa is defined as "stress value of shell material" and is required as input. Does anyone know what this value is or where to get it / how to calculate it. A formula is given for pressure stress (sigma) and then is says that "if sigma is greater than Sa, then use Sa as the stress due to design pressure".
Also, a second question, what is a good source for the yield strength at design temperature - also required in this calc.
Thanks for any help.
Georg.

 

[Tankman650]

The values for allowable stress and yield at any temperature for code material are given in ASME Section II, Part D.

I am familiar with WRC107 and do not recall any reference to Sy. The allowables are given based on stress intensities of ASME Sec VIII, Div 2 for primary and secondary stresses. I recall that allowables from the code are derived from ultimate tensile stress.

I am saying that I am suspect of the method you talk about since the derevation is unknown to me. I did notice several typos in my Megyesy book on this subject (10th edition)

You may have noticed that the material properties are give in the Megyesy book (on page 189) but the Code has revised allowable stresses as of 1999 and your edition of the book may not be current.

HTH

 

[jte]

Georg-

I'm not familiar with Megyesy's method, but you will be able to find Sy at temperature listed in table Y1 (roughly page 470) of Section II.

My experience would be that (for a Div. 1 vessel) the Div. 1 allowable stress Sa would be used with Div. 2 philosophy in evaluating nozzle stress results. The allowable stresses for Div. 1 did change for some materials, but not all. They are governed by either ultimate tensile or yield.

jt

 

[ume153]

Hi

Talking of allowable stress in WRC analysis, could some one clear this, what is the philosophy of allowable stress

is it,
1) 3 times the allowable stress value as per Div 1
or
2) 3 times the stress intensity value as per Div 2

Thanks in advance