Kellogg Pressure equivalent Pe vs Pr
Kellogg Pressure equivalent Pe vs Pr
(OP)
Following the Kellogg Pressure Equivalent Method, a Pe is determined, added to the max operating pressure for P and then compared to the flange rated pressure at the max operating temperature. This produces a simple, but conservative, result that will probably disprove a majority of flange connections (Peng).
I am reviewing a piping spec where the company compares the total (Pe + P) to 1.5*Pr (rated pressure).
My question is: "Does increasing the rated pressure by a factor of 1.5 represent a more "realistic" comparison or an approach that results in an under-designed piping system?".
I am reviewing a piping spec where the company compares the total (Pe + P) to 1.5*Pr (rated pressure).
My question is: "Does increasing the rated pressure by a factor of 1.5 represent a more "realistic" comparison or an approach that results in an under-designed piping system?".





RE: Kellogg Pressure equivalent Pe vs Pr
RE: Kellogg Pressure equivalent Pe vs Pr
RE: Kellogg Pressure equivalent Pe vs Pr
from this thread here,
http://www.eng-tips.com/viewthread.cfm?qid=18541
RE: Kellogg Pressure equivalent Pe vs Pr
From personal experience, a majority of flanges that come in with a (Pe+P)/Pr <= 1.5 will pass a Section VIII Div 1 Appendix 2 analysis.
It is possible that the engineer has looked at what could reasonably occur in the applications this spec is intended for and is okay with the 50% extra margin.
If I were in your shoes I'd like to know the reasoning, but the owner has final say.
FWIW, some process engineers love to set line conditions to the flange limits. (No matter the open ended drain line can't reach 285psig or that the water won't be water anymore when you go to 800°F and 80psig.) With ANY external loads on the flange, it would "fail" the Kellogg method without a multiplier on Pr. The spec engineer may be trying to avoid wasting your time and his $$$ qualifying flanges on such lines.
- Steve Perry
http://www.linkedin.com/in/stevenhperry
This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.