Pipe flange check

[SansengMech]

The ASME Sec VIII Division 1 Mandatory Appendix 2 'Rules for bolted flange connections with ring type joints' does not consider additional tension or bending moment but only pressure, internal or external. I observed that people used pressure equivalent method alsong with this to check flanges (thread378-18541

http://www.eng-tips.com/viewthread.cfm?qid=18541).

We have ASME Sec VIII Division 2 Para 4.16 'Design Rules for Flanged joints' and here both the external loading, additional tension as well as bending moment are considered. The question is why then we have to go for Div1 method along with peq instead of Div2 method all the time? Also, for API 6B and 6BX flanges, can we use ASME Div 2 method in addition to API 6AF, 6AF1 and 6AF2 methods?

 

[C2it]

ASME VIII Div 2 is a newer version. The old one was same as Div 1.

Since both are approved Codes, you should be able to use either, thus use Div 2 to consider external loads.

Why would you need to calculate API flanges when allowable loads are all quoted in 6AF2 ? The values in 6AF2 are all results from extensive 3D finite element analyses, which is far superior to Div 1 + Peq and Div 2.

 

[XL83NL]

I dont know all the ins and outs re this subject, however, remember Div 1 is used for design flanges for Div 1 vessels that are non-standard (i.e., other than e.g. B16.5), like body flanges. This document outlines an update to Div 1 towards a more consistent approach inline with Div 2;

https://www.scribd.com/doc/206851934/Eq-Pressure

Internally we use a modified Div 1 method for flange calculations, in which the rules of the document provided in the link have been used.

Apart from the equivalent pressure method, there's an enhanced/updated method to this which has been published by BFJ-gutu Warren Brown;

http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=1815390

 

[SansengMech]

@C2it: I agree that the approach of API 6AF2 is superior but the actual calculation is very difficult to automate as it involves reading off charts. So I was deliberating another method for which I will be able to create a excel based calculator. I created two, one for Div 1 and another for Div2. The next try would be to automate API 6AF, 6AF1 an 6AF2.
By the way, how should I interpret the word "Integral" in the title of API 6AF2 "Technical Report on capabilities of API integral flanges under combination of Loading - Phase II"? IN ASME BPVC Sec VII Div 1 and 2 in comparison to API Spec 6A define the type "integral" differently. Or is it only me?