DN notion for PED 97/23/EC categorization

[EGVCCA]

Hello everybody,

I want to calculate the PED category for a pipeline whose dimensions are 84x2x6000 according to EN 10217-7. Which is its DN?

PED guideline 2/2 throws some light on this issue but, how to know whether the notion DN exists in a specific standard (for instance, EN 10217-7)? In the case of the beginning, do I have to categorize with DN=84 or with DN=80?

I have found in ASME specifications a table with equivalences (for example NPS1 = DN25, NPS1 1/4= DN32...) but what if this equivalence does not exist as in the former standard EN 10217-7?

Thanks in advance!

 

[XL83NL]

Assuming 84x2x6000 is OD times wall thickness times length, then as I see it this would be a DN80 (84 - 2x2 = 80) acc. guideline 2/2. Dont see any reason to do it else, Id go for that

 

[EGVCCA]

Thank you very much for your quick response!

But I would like to know your opinion about one question: if instead of an European standard (as EN 10217-7 is) my pipeline is to be manufactured with, for instance, 2" SchSTD A 106 GrB (OD60,3 mm - SCH 3,91mm) (American standard), what DN should I have to choose for PED categorization? DN50 or ID 52,48mm?

I´m a bit confused with the following Guideline 2/2 sentence: "in the absence of DN in the standards...". How to know whether the notion DN exists in a specific standard?

Thanks in advance!

 

[XL83NL]

I see where youre getting at. 2" is actually a listed DN size, its 'in the standards..', so just stay with that.
I think the DN system roughly equals the OD minus twice the wall thickness of a 40/STD pipe. and then rounds off.
if u need to know which DN sizes exist, just google and youll find all of them (here's an example)

 

[EGVCCA]

Thank you very much, I´ll do that then!

The reason why I´ve been thinking this matter over is because I find quite disproportionate that for the categorization of a pipiline that has DN notion its Schedule is not taken into account. For example, for 1" Sch5D (internal diameter 30,1 mm) and 1" XXS (internal diameter 15,22 mm (almost the half!))the DN will be the same for both (DN25.

Best regards.

 

[XL83NL]

Yep, some things have been always that way and no one ever questions them again, even though they might not make sense.

PS: pipelines are not covered by the PED. I assume youre talking piping.

 

[EGVCCA]

Yes, for sure! I´m talking about piping, not pipilines, sorry for my translation!
Thank you so much,
Elisa