Flange rating 1

[PDSVINOD]

I have a class 900# piping spec. The materials engineer specifies up to 2.5" size the rating as 1500#. I know the dimension for 900# & 1500# matches up to 2.5".

But during the dicussion , I was told that the as per code it is wrong to specify flanges below 3" to be 900#.

So I would like to know , is is wrong to specify as per code , the following.

2" CL 900# flanges as per ANSI B 16.5
or whether I should say
2" CL 1500# flanges as per ANSI B 16.5.

Regards

 

[pennpiper]

Call your flange supplier and ask if there is any cost difference or warranty differences.

 

[jte]

Perhaps a visit to the land of Interpretations would be enlightening!

See B16.5 Interpretation 4-9 on page I-4 of the 2003 ed:
Question: In accordance with ASME B16.5-1996 para. 4.14, may flanges NPS ½ through 3½ meeting all of the requirements for Class 600 be marked to show conformance with both Class 400 and Class 600?

Reply: Yes.

Now, I can't quite follow the paragraph reference, but it would appear that, similar to dual stamped materials, dual rated flanges are acceptable. The note to use Cl-1500 dimensions in the Cl-900 dimension table does not state "Use Cl-1500 flanges for these sizes." It states that you should use the CL-1500 dimensions. Thus, a 2" CL-900 flange is a legitimate callout.

Having said that, why not call for Cl-1500 flanges? I don't see that the higher rating class hurts and it may be of some use 20 years from now.

Just remember: I'ts not ANSI B16.5. It's ASME B16.5. Unless you are referring to an earlier edition. 1984 was ANSI, 1988 was ASME/ANSI, 1996 thru now its just ASME. Page vii of the 2003 ed. And they're not 900# flanges. They're Cl-900 flanges. Since the 1970's if I recall correctly.

jt

 

[11echo]

This is one of those "catch 22" things in the piping industry. Basically there are NO piping flanges in the 900# class below 3"! ...AND if you wanted to deal with pipe in those smaller sizes and pressure ranges then you would have to use 1500# class flange ratings. And "if" anybody indicates different, then you know they don't know what they are talking about! ...Good Luck!

 

[JLSeagull]

11echo is correct alghough the tone seems a bit harsh. Line specifications set the flange class based upon the maximum pressure and temperature.

The required flange ratings are also affected where flanges in material groups not specified as the piping material. Sometimes instruments require a different flange material. If the piping system pressure and temperature ratings are toward the top of the carbon steel materials, a higher flange class may be required for the instruments.

The pressure rating for lines smaller than NPS 3 may be Class 900. With Class 900 flanges, for lines smaller than NPS 3, ASME B16.5 refers to use Class 1500 for the dimensions. Notes require Class 1500 for the small pipe sizes Class 900. Use ASME B16.5 Class 1500 flanges in lines below NPS 3 for Class 900 piping systems.

 

[PDSVINOD]

JLSeagull & 11echo,

Thanks for the reply.
ASME B 16.5 says , for dimension of CL900 flanges below 3"
refer to the table for CL1500.

I am looking for a reference in the code , which mentiones that below 3" in CL900 , the call out should be CL1500.
In other words , does the code prohibits the call out " 2" CL900 flange as per ASME B 16.5"?.

Vinod

 

[11echo]

Uh-Ooh ...Did mean to come off "harsh"!!! ...I had an incident recently where an engineer was try to tell me to use 2"-900#RF flanges, and was alittle indignant when I told him there are no such things! However it was “fun” setting him straight.

...PDSVINOD The code prohibits the callout because there is no such thing! When I see this type of thing (that, backward weld symbols, & etc.) It starts hint the engineer/designer(s) really doesn't know what they are doing & I start to question their work!

 

[jte]

The code prohibits the callout because there is no such thing!

11echo- Care to "set me straight" by quoting chapter and verse of B16.5 where it says so?

jt

 

[JLSeagull]

"Notes require Class 1500 for the small pipe sizes Class 900."

Look at table 5 General Note
(f) Use Class 1500 in sizes NPS 1?2 to NPS 21?2 for Class 900.
and F5, General Note "(3) Use Class 1500 in sizes NPS 1?2 to NPS 21?2 for Class 900."
Table 17 in the rows from NPS 1.5 through 2.5
Use Class 1500 dimensions in these sizes.

If you read the comments and reviewed B16.5, by now you are more understanging. Still, if these type notations don't satisfy your ignorant checker or whomever is commenting, just go with the flow and call out Class 900. The BOM will still provide Class 1500 in these sizes because, no Class 900 piping flanges exist below NPS 3.

 

[jte]

JLS-

As you pointed out, General Note (f) in Table 5, Dimensions of Ring Joint Facings does indeed state Use Class 1500 in sizes NPS 1?2 to NPS 21?2 for Class 900. However, Tables 17 (Templates for Drilling Class 900 Flanges) and 18 (Dimensions of Class 900 Flanges) state Use Class 1500 dimensions in these sizes.

Now, I'll ask you to go back to Table 5 and read note (e). Please also take a look at Tables 14 and 15. These deal with the very same issue but for CL-400 and CL-600 flanges. In fact, the arguments would seem to be identical.

So, why would I presume that the Committee would not use the same logic for CL-900 / CL-1500 flanges as they did for CL-400 / CL-600 flanges in Interpretation 4-9? Based on the "small bore CL-900 flanges are prohibited" logic, there would be no CL-400 small bore flanges either.

Am I missing something here?

jt