EN 13480 - Straight Pipe Thk Calculation

[DN800]

Dear all,
this is my first thread and I hope I've found a good source of info. I'm a mechanical piping engineer and at the moment I'm converting DIN pipes to EN ones and checking if what offered by suppliers is acceptable for my design conditions. I've done an excel file and trying to amtomatize the matter. But I've got some doubts because, compared to ASME code, the EN one makes a lot of references to other std. and with only one Norm it's not possible to calculate anything.

Ok here the questions. For expert designers probably some could sound stupid questions, but I think it's better to be sure.

1. With reference to fig. 4.3-1 della EN13480-3, which is the correct thickness tolerance (c1) to be used for a pipe supplied according EN10216-2? At par. 8.7.4 of this Norm there are four different tables, n.7, 8, 9, 10 (Tolerances on outside diameter and wall thickness; Tolerances on inside diameter and wall thickness; Tolerances on outside diameter and minimum wall thickness; Tolerances on inside diameter and minimum wall thickness). Do I have to evaluate the tolerance in each table and consider the biggest? Or is it possible to consider e.g. only tolerance at. tab.7?

2."A" - Elongation at rupture, to be used for straight pipe thickness calculation. Normally longitudinal and transversal min. elongations are indicated in the Norms (e.g. EN10217-7 tab.6 pg. 18) regarding technical conditions of supply for steels. Shall the lower (usually transversal) be used to calculate the minimum required thickness to withstand pressure "e"?

3."z" joint coefficient (defin ed at par. 4.5 pg. 18) to be used for straight pipe thickness calculation, is relevant only to pipes requested/supplied welded? This seems confirmed by the note at the same paragraph, that refers to Tab. 8.3-1 of EN13480-5.

4.Design stress "f". For the calculation of min. required wall thickness for straight pipes, par.5.1 specifies that "the lower of time-independent stress value as calculated in 5.2 and the time-dependent stress value as calculated in 5.3 shall be determined for each design and test condition". Where do I find SRTt? For example for a pipe made of 1.4301 and requested as per EN10217-7? Is it sufficient to evaluate f only with 5.2?

THANKS A LOT.
Regards,

DN800

 

[Drexl]

Hi,

This is how I understood it:

1. If you buy a pipe specified by Do x s so you only have to use that to calculate. If you for some reason order using option 11 in EN 10216-2 then you have to calculate by the other parameters.

3. Yes z is only for welded pipes (as opposed to seamless).

4. In the material standard, see Annex A of EN 10216-2 for example. If you don't have high temperatures and therefor know you are not in the creep range you don't have to calculate time-dependent stress.

Drex