Dear All,
I'm performing the flange verification by pressure equivalent method but I have some problem specially with 2inch-3-inch flange diameters; The verification usually fails;

The verify is Ok if PeqRegarding DP, Is it necessary to use design pressure or operating pressure is also correct?
How can I resolve my problem without change my flange rating?
Thank you to all..

You probably need to do a more accurate analysis. Consider ASME VIII Div 2.

Thank you for you reply; Yes, I will do flange verification by ASME VIII because pressure equivalent method is too conservative, but I don't understand how Caesar perform flange leakage verification:

LEAKAGE SAFETY FACTOR: (If less than one then joint
leakage is predicted.) (Allowed/Actual)

Pressure Only (Ci-Creq)/Cp ............. 6.53
Force Only (Ci-Creq)/Cf ................ 1861.67
Moment Only (Ci-Creq)/Cm ............... 114.38

Pressure+Force+Moment (Ci-Creq)/CL ..... 6.16


What are Ci, Creq,CL... etc and In which section of ASME code can I find these formulas?

The flange leakage analysis (and the definition of those terms) can be found in the CAESAR II documentation. These are not ASME terms.

I have Caesar manual but I don't find those parameters and relative formulas. If is possible, Can you attach the Caesar section where I can see those parameters?

Thank you..

The discussion of Flange Evaluation can be found in the "Equipment Component and Compliance" chapter of the User's Guide.

The definition of those terms is listed just above the output you sited, in the output report. You can find additional discussion on this topic in the "October 1991" Newsletter, available on this website.

Dear Richard,
Ok it is clear, but I have the last two doubts regarding flange leakage verification:
1)Flange leakage analysis by ASME VIII, Div.I, Appendix 2 is valid both raised and Ring Joint Flange?
2) I have ASTM A-694 Gr. F65 flanges (6-inch, 8-inch,10-inch are flange diameters); Caesar database does not own this material, then I have to put allowable flange stresses by hand; Can I refer to MSS SP-44 Code?, where the following allowable stresses are listed:

Longitudinat Hub stress 205 Mpa
Radial flange stress 140 Mpa
Tangential flange stress 140 MPa
Average stress 140 Mpa

Otherwise, Which allowable flange stresses Can I consider for this material?


Thank you very much

ASME VIII Div 1 Appendix 2 doesn't really address leakage. This appendix is for the evaluation of flange stresses.

Yes you can define your own allowable data.

Yes, sorry... ASME Is for flange stresses, but the calculation is valid both raised and ring joint type flange??

If you read that newsletter article from 1991 you will find the complete discussion on the leakage method employed. This method takes a slice through the flange and treats it like a cantilever. The type of flange just changes the geometric properties of the cantilever.

This is a leakage approximation at best, but there is nothing better.

Hello

I'm not sure if this is the forum for this sort of question but it seemed relevant to my issue when losely associated with the term 'failure' and flange checks.

I have found that when changing pressure ratings from 900# to 600# piping with associated flange checks, somehow the 600# pressure rating persists! In other words when I continue the model and wish to revert to the 900# rating for further flange checks, the 600# gasket details keep returning! In the same way in which parameters such as pipe size, temperature, pressure etc., carry over unless the user changes one of these, there appears to be no way to force the program to reset the flange rating.
Can you help?
Best regards
Alex

Richard

I found that when I maually change the Gasket Diameter, G, in the auxiliary data screen then the correct dimension persists, i.e. follows to the next data point unless modified.

OK, so issue resolved!

Best regards

Yes that is correct. We designed the interface to "carry the flange data" forward, assuming that in most instances the pressure rating wouldn't change all that frequently in the model.