Small Flanges not OK with EN1591 and R2 V32

EN 1591, ASME Div. I, AD2000, DIN2505, ...
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r2user_0209
Beiträge: 10
Registriert: Di 28. Feb 2012, 15:16

Small Flanges not OK with EN1591 and R2 V32

Beitrag von r2user_0209 » Mi 3. Mai 2017, 14:34

Hi

Some time ago I build a ROHR2 model with all flange-types and sizes of a given pipe class and I performed a flange analysis according to EN1591.

With the new ROHR2 version (32.0) I opened the model and recalculated it. To my supprise the smaller flanges now are overloaded even though at the time the whole pipe class was OK.
What has changed with the new version? Do I have to revise my pipe-class?

Best regards

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rohr2support
Beiträge: 346
Registriert: Mi 14. Sep 2011, 08:23

Re: Small Flanges not OK with EN1591 and R2 V32

Beitrag von rohr2support » Mi 3. Mai 2017, 14:39

Hi

Can you send us the model on "support @ rohr2.de"?

Best regards

Rohr2 Support

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rohr2support
Beiträge: 346
Registriert: Mi 14. Sep 2011, 08:23

Re: Small Flanges not OK with EN1591 and R2 V32

Beitrag von rohr2support » Do 4. Mai 2017, 11:31

Hello

The problem is the version 2014 of EN1591. This version was implemented in ROHR2 Flange in version 32.
The way the creep is taken into account has changed from a force factor PQR to displacement delta_eGc.
The calculation of this displacement is defined in appendix F and unfortunately this calculation is wrong.

The force to correct gasket creep DOES NOT DEPEND ON THE SURFACE OF THE REAL GASKET but on the surface of the test-gasket. For small DN/PN this constant correction force gives a huge change in gasket pressure for the small gasket area. All DN15 Flanges using soft gaskets fail in calculation! On the contrary for big DN/PN the correction force is negligible and does not change the gasket pressure. For big flanges the EN1591 version 2014 CONSIDERS NO CREEP.

Here is a detailed description of the problem and the proposal we have made for resolving this issue:
Annexe_F.pdf
In the meantime I would suggest using the version 2011 of the EN1591, at least for soft gaskets.
You can change that in ROHR2Flange using the Menu "Setting"->Standard
Flange_EN1591_2011.JPG
and then recalculate all flanges.

Best regards

Rohr2 Support
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