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E610/7 occurs in a calculation
02-05-2016, 04:29 PM, (This post was last modified: 13-05-2016, 01:16 PM by shaswin.)
#1
E610/7 occurs in a calculation
I have a pipeline with local a diameter of 2463 mm and a wallthickness of 531.5 mm (local stiffened rings to influence positive ovalisation in the pipe at the miter bends). The diameter/wallthickness ratio is 2463/531.5 = 4.634
This is lower then 5, so no calculation is done for DF 6.1. According to the changelogs this error check is new in v4.4.0.

Better is to do also 3D stress calculation for thick-walled pipes (Dgem / d < 20, see article 8.5.2.1 NEN 3651:2012) given by this formulae:
   
(Source: D.3.1.1 NEN 3650-2:2012)

Ple4Win does only a 2D stress calculation with this formulae, which is normal for thin-walled pipes (Dgem /d ≥ 20, see article 8.5.2.1 NEN 3651:2012):
   
(Source: D.3.1.1 NEN 3650-2:2012)

A wish is to give a warning instead of an error for the hardcoded limit Diam/wallth < 5 for a 2D stress calculation, because in the previous version v4.3.1 this was allowed or allow a 3D stress calculation given by the first formulae above. As a workaround I have to calculate this project with Ple4Win v4.3.1.

I have addded the project file for this case.


Attached Files
.zip   BC4.zip (Size: 1.23 MB / Downloads: 1)
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20-05-2016, 11:06 AM,
#2
RE: E610/7 occurs in a calculation
Thanks for your background information, we are already looking into the modeling of thick-walled pipelines. We are also looking for ways to (correctly) taking stiffening rings into account. Ticket no. J-1885 has been assigned to this issue.

For now, we will keep the hard limit of D/t < 5 (in design function 6), as we feel that the calculated results with a lower D/t do not match reality at all. So we want to stay on the safe side of things.

So for stiffening rings you have to obey the limit for now. If you feel your rings aren't stiff enough with that ratio, try modeling these a bit different by either using wider rings or by locally changing the material parameters to a stiffer material.
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09-08-2016, 10:51 AM, (This post was last modified: 09-08-2016, 11:03 AM by shaswin.)
#3
RE: E610/7 occurs in a calculation
(20-05-2016, 11:06 AM)Dr. J Foerster Wrote: Thanks for your background information, we are already looking into the modeling of thick-walled pipelines. We are also looking for ways to (correctly) taking stiffening rings into account. Ticket no. J-1885 has been assigned to this issue.

For now, we will keep the hard limit of D/t < 5 (in design function 6), as we feel that the calculated results with a lower D/t do not match reality at all. So we want to stay on the safe side of things.

So for stiffening rings you have to obey the limit for now. If you feel your rings aren't stiff enough with that ratio, try modeling these a bit different by either using wider rings or by locally changing the material parameters to a stiffer material.

Jens,

Most of the standard ASTM pipes lower then DN50 can't be calculated with Ple4Win due to error E610-7, see screenshot below marked with a yellow background colour. I have also attacheded the calculation in an Excel file.

   

Modeling the smaller ASTM pipes above ground for the stability/displacements calculations is currently not possible in Ple4Win v4.4.0.


Attached Files
.xlsx   Error 610-7.xlsx (Size: 20.86 KB / Downloads: 1)
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26-08-2016, 10:26 AM,
#4
RE: E610/7 occurs in a calculation
We are aware about this limitation, but still feel not comfortable to replace the error with a warning without changing the calculation method.
We are discussing intermediate steps, and I also increased the urgency of the thick-walled pipe calculations change request.
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26-08-2016, 08:14 PM, (This post was last modified: 26-08-2016, 08:14 PM by shaswin.)
#5
RE: E610/7 occurs in a calculation
Thanks for increasing the priority.
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18-10-2017, 12:03 PM,
#6
RE: E610/7 occurs in a calculation
One may also want to simulate a thickwalled ring with external forces without soil to check internal stresses in the ring.
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24-10-2017, 11:35 AM,
#7
RE: E610/7 occurs in a calculation
Defining external forces working on the outside of a pipeline as an additional load is also an option for future developments.
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06-11-2017, 12:15 AM,
#8
RE: E610/7 occurs in a calculation
It would be nice indeed.
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