According to NEN 3651:2012 paragraph 8.5.2.1 there are two different formulas for the calculation of the hoop stress.

There is a different between a thin-walled and thick-walled pipe.

Formula hoop stress for a thin-walled pipe [

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Formula hoop stress for a thick-walled pipe [

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Ple4Win (v4.2.2 build 12112) uses always the thin-walled pipe formula. There should be a difference between a thin-walled and thick-walled pipe in the calculation of the hoop stress.

It should be noticed that the formulae for the hoop stress are given for the so-called 'simplified' strength calculation. In general NEN 3651:2012 paragraph 8.3.1 refers to NEN 3650 parts 1 to 5 for the (hoop) stress calculation, where only the formula for the thin-walled pipe is given.

The formula for the thick-walled pipe changes to the formula for the thin-walled pipe if D/d approaches infinity.

Originally PLE has been developed for the strength and stability calculation of 'thin-walled' pipelines.

The hoop stress calculation in the NEN 3650 module is based on NEN 3650-2:2012. Nevertheless it is always good to apply a more accurate formula.

Thank you for your remark.

No problem Rien.

When you will apply this formulae in Ple4Win the ratio D/T column from the PIPEDIM output table should be changed. D shouldn't be the external diameter but the average diameter and T should be T-MIN. So the ratio should be Dg/T-MIN.

The wanings should be also updated when changed.

This part of the helpfile should also be updated: Ref: Tables Reference > Output Tables > Pipe dimension data [PIPEDIM] > Table error description / ID: H310523

Hi Shaswin,

This is to inform you that we are investigating the possibilities to incorporate the behaviour of a thick-walled pipe in PLE. These pipes may occur especially in offshore environments with high internal pressure.

It is not only a matter of a different hoop stress, but it has an effect on internal forces and upheaval buckling risks as well. Of importance is the DNV code DNV-OS-F101 for submarine pipeline systems.

This issue has also been assigned to ticket no J-1885, see

this topic for more about thick-walled pipelines