max bolt load values on EN 1092-1 flanges

[swiss037]

Question for people who work with EN and/or DIN norms about flanges:

Which norm (and where in it) gives you the
"Maximum bold load on flange" / "Maximale Schraubenkraft auf den Flansch" / "Charge maximale de la boulonnerie sur la bride"
... which is defined by the flange alone (before any consideration of bolts and gasket)?

-----------example-----------
For a steel flange PN 63, DN 100 (according to EN 1092-1, 8 x M24 bolts), one source* suggests me a max bolt load on flange of 278 [kN].
This source claims this value comes from EN 1092, but I really can't find it in EN 1092. Do you know where it might comes from?
Let me just add, although maybe I shouldn't, that I have vaguely heard of these 278 [kN] resulting of some conservative value of stress of 30 [N/mm²] -somewhere in the flange around those bolts-.

*: this source is the online tool KemProof and trying different flanges (EN 1092-1) gave me the following values:
[pre]
[ul]
[li]PN 63, DN 100 (8 x M24 bolts): 278 [kN] (same value for PN 100: 8 x M27 bolts)[/li]
[li]PN 40, DN 100 (8 x M20 bolts): 256 [kN] (PN 16 has less, PN 6 even less (clear trend) but PN 10 (8 x M16 bolts) has a surprising 409 [kN])[/li]
[li]PN 63, DN 50 (4 x M20 bolts): 136 [kN] (same value for PN 100: 4 x M24 bolts)[/li]
[li]PN 63, DN 150 (8 x M30 bolts): 411 [kN] (same value for PN 100: 12 x M30 bolts)[/li]
[/ul]
[/pre]
----------------------

My personnal guess for the max bolt load on flange would have been to follow EN 1591-1 §6.4.
I'm about to do it but it looks complicated and I'm not even sure it will give me what I need.
What do you think about that? Any other suggestion?
Does anyone know a source for max bolt load values on EN 1092-1 flanges?

By the way, max bolt load should depend on the material's properties at the given temperature and other parameters, which EN 1591-1 seems to take into account, whereas Kemproof doesn't, or simply assumes the worst case (which is defined I'm not sure exactly where...).

Thanks for reading!

 

[denlow60]

you mean something like this

 

[swiss037]

thank you denlow60, but all I see in the document you provided (excerpt from EN 1092-1) are PN 63 flanges dimensions, in [mm].
so in a way, it is indeed what I mean as context, yes.
however, my questions remain to be answered.
have a good weekend!

 

[XL83NL]

So what you want to knoq, is which force is required to break the flange? You should consider that bolt load will almost never be governed by the flange material. The gasket or the bolt's tensile stresses will come first, except maybe for custom designed flanges (which is not your case). Second, such calcs may be so complex you require a FEM approach.
Furthermore, flange calcualtions have been a topic of a lot of discission and research, both on this board, but also in a lot of papers (a good place to start is e.g. the ASME digital paper collection).

Having said that, Ill elaborate a bit more, as from (my little) experience I know the hassle that comes with all these fairly new EN-standards and their current shortcomings and bugs.

What you could do, which is similar to ASME's apporach, is to do an ASME VIII div 1 appendix 2 calc.
Hwoever, since youre using EN flanges (and I know from experience the hassle with all these new EN-standards), you require to do the calcs acc EN 1591-1.
Now, calcs according this standard are quite tricky. You can easily make an VIII-1 app. 2 calc in Excel. For EN 1591-1, well, Ive never heard anyone being able to do this.

There are some (commercial) alternatives, e.g. TEMES fl.cal. This is a piece of software developed by the same guys who are involved in the working groups that also publish the EN 1591-series and (I believe) EN 1092-series. You might contact amtec, the manufacturer, and see if they can inform you if their software can do the calcs you require.

Googling on EN 1591-1 will also give you a lot of useful results to start with!

Good luck and let me know if youve been able to come up with something.

 

[swiss037]

thanks again, XL83NL!

let's take some of your points, one by one:

1. The gasket or the bolt's tensile stresses will come first, except maybe for custom designed flanges (which is not your case)
that's what I would have thought, but remember my example with Kemproof? for 45 bar of internal pressure at 250°C, with 3 graphite gasket variations*, and 1.4913** bolts, each time resulted in a 1238 kN bolt load requirement, far exceeding the suggested 278 kN max bolt load...
*:
[ol 1]
[li]Flat A1 Rivatherm-Super "grabble reinforcement" 2K110[/li]
[li]Flat A1 graphite-"tanged reinforcement"[/li]
[li]"TFG9A" "Top Flat Gasket" SS-graphite[/li]
[/ol]
**: I picked this material almost randomly: X 19CrMoNb V N 11-1 with Rp0.2 = 750 [N/mm²] at 20°C and Rp0.2 = 627 [N/mm²] at 250°C

2. ASME digital paper collection
looks nice, especially those 3:
[ul]
[li]Brown and Reeves, Considerations for Selecting the Optimum Bolt Assembly Stresses for Piping Flanges, 2006, Paper No. PVP2006-ICPVT-11-93094, pp. 137-143; 7 pages[/li]
[li]Brown and Reeves, An Update on Selecting the Optimum Bolt Assembly Stress for Piping Flanges, 2007, Paper No. PVP2007-26649, pp. 51-57; 7 pages[/li]
[li]Brown, Selecting the Optimum Bolt Assembly Stress: Influence of Flange Material on Flange Load Limit, 2008, Paper No. PVP2008-61709, pp. 785-791; 7 pages[/li]
[/ul]
I will try and see if I can find those at libraries around me...

3. ASME VIII div 1 appendix 2 calc
yes, looks fine, actually for any flange: EN, ASME, ... I'm keeping that in mind.

4. "EN 1591-1"; "TEMES fl.cal"
EN 1591-1 §6.4 is looking more and more worth a try to me. I might see what can be done w/ or w/o spreadsheets and (if I do or rather when, could be a long time) will get back to you.
TEMES fl.cal looks legit, there's a free online version but I'm doing something wrong and it can't generate a result, nor do I know what I did wrong. I guess buying the software (>3000 EUR) could be a good move, but...
...context as to why I'm not pushing too far: this work is for my studies (almost no supervision), but the client and his needs are real. as a result:
[ul]
[li]I have to refrain from going too far (buying software, spending too much time unefficiently, ...)[/li]
[li]I'm motivated and I wouldn't be surprised if the work suddenly became a true contract[/li]
[/ul]
... actually I've already exchanged emails with AMTEC (Manfred Schaaf and Co!), so I could very well ask them what I did wrong.