Pipe class corresponding to PN ratings 2

[Jerrypotter]

Hi folks,

Several handbook corelate pipe class rating based on ASME B 16.5 with corresponding PN numbers as below:

Class 150 300 400 600 900 1500 2500
PN 20 50 68 110 150 260 420

Is there any code/standard specifying it? Can we take as basis for class vs pressure design consideration?

Because PN values (in bar) are closely matching with values given in ASME B 16.5, Table 2-1.1 for group 1.1 materials only. (for −29 to 38 deg C.)

Thanking in anticipation.

 

[XL83NL]

Perhaps in EN 1759-1 (or ISO 7005)?

Huub
- You never get what you expect, you only get what you inspect.

 

[LittleInch]

Short answer is no. IMHO

The P-T ratings from ASME B16.5 are one set of ratings, the PN ratings a different set.

The PN pressure temperature ratings are defined in EN 1092 as for a RT of -10 to 50C These are 6,10,16,25,40,63 and 100 bar
The ASME B 16.5 ratings for group 1.1. materials at 38C are nominally 19.1,51.1,102.1, 153, 255

Rather confusingly there is also an EN 14870 which is more attuned to pipelines and pieline strength materials which in table 2 has a set of common ratings

So PN 20,50,100,150,250 and 420 aliging directly with ASME class 150, 300, 600, 900 and 1500

Piping and equipment including valves I believe use the EN 1092 designations.

So pick your design code carefully.

It's far from uncommon to find class 150 level piping limited to a 16 bar design pressure due to some component being supplied with PN 16 flanges or only rated to that pressure within a valve or piece of equipment.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[shvet]

para. 7.2 EN 13942:2009

 

[LittleInch]

shvet,

Like this?
7.2 Pressure and temperature rating
The nominal pressure (PN) class or the ASME rating class shall be used for the specification of the required
pressure class.
Valves covered by this International Standard shall be furnished in one of the following classes:
1) PN 20 (class 150);
2) PN 50 (class 300);
3) PN 64 (class 400);
4) PN 100 (class 600);
5) PN 150 (class 900);
6) PN 250 (class 1500);
7) PN 420 (class 2500).
Pressure-temperature ratings for class-rated valves shall be in accordance with the applicable rating table for
the appropriate material group in ASME B16.34.
Pressure-temperature ratings for PN-rated valves shall be in accordance with the applicable rating table for
the appropriate material group in EN 1092-1.

And that looks like a valve specification?

It seems to say it's still subject to each codes P-T and material rating table

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

So I think whilst there is general consensus that some of the PN ratings are broadly the same as the ASME B 16.5 ratings, it all comes down to the specifics of material and temperature ratings of the particular flanges and their different standards.

Do have a specific issue or is this a general query?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[shvet]

@LittleInch
Topicstarter asked "handbook corelate pipe class ... as bellow Class ... PN ... Is there any code/standard specifying it?" and made it with some mistakes (see #300 and #400). As I understood question concerns ASMEvsPN only, not valve specifying. So I provided a link to para. where ASMEvsPN is specified.

 

[Jerrypotter]

@XL83NL
Yes,values(Class Rated)given in Table 2-1.1(ASME B16.5)is matching with values(PN Rated) given in Table E.5(ISO 7005-1:1992).
Hence, we can corelate this Class-PN relation for flanges.
Also same values are also matching with values(Class Rated) given in Table 2-1.1 (ASME B16.34).
So, we can again corelate this class-PN relation for valves also.

@LittleInch
I agree that values defined in Table-G(EN 1092) are different even after interpolating values in PN.
I don't see any relevant values EN 14870.
This is my general query,but I think handbook authors have come up with this summary considering ASME-ISO standard similarity.
Still I believe to go ahead with your point." it all comes down to the specifics of material and temperature ratings of the particular flanges and their different standards."

@shvet
As per EN 13942, I see PN values are slightly differing in PN.(Like for 400#,PN 64 instead of PN 68 and so for 600#,1500#). I have attached reference from valve handbook also. Values of PN are also different against pressure class.

Conclusion:
We need to refer code/standard every time to design according to project requirements. Class-PN relation seems true based on above comparison of ASME B16.5, ASME B16.34,ISO 7005-1 but we can't generalize it.