Calculation of the wall thickness for a vertical HDPE pipe immersed in water 1

[Yahyaoui Amin]

hi !

how can i calculate the wall thickness for a vertical HDPE pipe immersed in water subjected to internal pressure ( Gaz pressure) and external pressure (water pressure)

is there any standard or code for it ??

thank you in advance

 

[KevinNZ]

Yes there are codes for PE pipe. What you can use depends on the country and industry you are in.
Calculation of wall thickness when the internal pressure is higher than the external is easy.

Have a look at your code or

http://www.vinidex.com.au/technical/pe-pressure-pipe/external-pressure-resistance/

for external pressure.

 

[Yahyaoui Amin]

thanks a lot for your help

 

[LittleInch]

PE pipe tends not to be calculated, but already comes ready made in terms of pressure rating depending on grade of PE.

If the internal pressure is constant then you can normally subtract the external pressure.

The problem comes either during installation when it's empty or later on if it becomes de-pressurized.

PE really doesn't like external pressure and depending on the size, PE grade, SDR and time spent in this condition , this can be as little as 1 day at 15m Water depth.

The longer the PE is subject to external pressure, the lower the allowable external pressure.

This table is one I use supplied by a pipe vendor for PE 100. Numbers are pressures in bar.
I've also seen one which looked at different % out of roundness versus pressure and it wasn't pretty - basically a few % (3-5) and the resistance to external pressure becomes non existant

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