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Manpreet Singh
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Join Date: Aug 2010
Posts: 33

32", 2500#Class Blind Flange Resulting Higher Hub Thickness

06/24/2011 10:03 PM

Dear All,

Please help me out with below query:-

Blind Flange of 32" and 2500# is not listed in ASME B16.5,

Design code AS2885 which has no flange calculation formula so Blind thickess calculation was done as per UW-34 (ASME Sec viii div 1) which came approx 48mm whereas adjacent fitting to be welded is of 26.4mm thk (fitting thk as per AS2885).

Since all variables(pressure, temperature) are same for both fitting and flange then could somebody please provide some code referece which says that Flange can be of same thickness as of fitting i.e. 26.4mm

also when calculated flange hub thickness as per AS2885, it came same as of fitting 26.4mm, Please give your inputs as this question has kept us on hold for a long time..

Regards

Manpreet Singh
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Tornado
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#1

Re: 32", 2500#Class Blind Flange resulting higher hub thickness

06/24/2011 11:50 PM

No, the flange thickness cannot be the same as the lesser thickness of the pipe, fitting, or hub. This is partly because the flange is flat rather than curved, and partly because of bending moments from bolt/gasket forces.

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Manpreet Singh
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Posts: 33
#2
In reply to #1

Re: 32", 2500#Class Blind Flange resulting higher hub thickness

06/25/2011 4:28 AM

Hi Tornado,

Thanks for your kind reply, i understood there is some reason that we can't have same thickness of flange as of fitting (26.4mm) but we need to taper flange thickness to 39.6mm (1.5 of fitting thk, max. allowed by code) would that be permissible?

Also as per your experience having all variables same (design perssure, temp...) thickness difference of this much (48-16.4 = 27.6) has been seen before?

Please guide me...

Regards

Manpreet Singh
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pritam
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#7
In reply to #2

Re: 32", 2500#Class Blind Flange resulting higher hub thickness

06/26/2011 1:52 AM

Which fitting exactly you are talking about? Is it a bend or equal Tee or unequal Tee and whether its same size? How and why you will connect it with blind flange? A sketch would have helped. In any case it is not advisable to reduce the thickness of the blind flange.
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Anonymous Poster #1
#3

Re: 32", 2500#Class Blind Flange resulting higher hub thickness

06/25/2011 10:03 AM

kneedeep...

You are asking very good questions, but you must understand that you are in an engineering realm that separates the men from the boys.

What are your maximum operating pressures and temperatures ? By what process does this sytstem become Class 2500 ?

What specificly is you code of design ?

If indeed this is a system to be based on the US developed ASME B31.3 standards, have you ever heard rumors of ASME B16.47 ?

Best regards

- The Irish Phantom
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Tornado
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#4

Re: 32", 2500#Class Blind Flange resulting higher hub thickness

06/25/2011 10:43 AM

A picture would help. A blind flange is just a disk, with bolt holes and possibly a raised gasket face, but where is the hub?

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Mukesh0861
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#5

Re: 32", 2500#Class Blind Flange Resulting Higher Hub Thickness

06/25/2011 2:01 PM

For 32" X 2500# system as per ASME B16.5, thickness of 26mm or so is not possible. Please check your specification or the system requirements. If it is really 32" X 2500#, system, even alloy steel,hub thickness will not be less then 54mm.
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MJCronin
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#8
In reply to #5

Re: 32", 2500#Class Blind Flange Resulting Higher Hub Thickness

06/26/2011 10:08 AM

Mukesh..

Where do you find 32 inch flanges in ASME B16.5 ?

The ASME dimensional code B16.5 runs to 24 inch, ASME B16.47 has two series of sizes (A and B sizes) above 24 inch.

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Abdel Halim Galala
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#6

Re: 32", 2500#Class Blind Flange Resulting Higher Hub Thickness

06/26/2011 12:08 AM

May be there is a misunderstand and certain confusion between thickness of the neck of a flange and thickness of flange itself.

The thickness of the neck of a welded neck flange must come with the same thickness of the fitting or pipe which will be connected by butt welding. And may be the thickness of blind flange (min. thickness of the circular plate) shall come with the same thickness of that welded neck flange (flange itself not its neck).

Welded Neck Flange (go = neck thickness & t = Flange Thickness)

Blind Flange (T = Thickness of Flange, without neck flange)

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Abdel Halim Galala
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#9
In reply to #6

Re: 32", 2500#Class Blind Flange Resulting Higher Hub Thickness

06/26/2011 11:50 PM

For more details on blind flange thickness calculation, see CR4 Thread: Calculation-of-blind-flange-thickness, and free download this PDF file: Blind_Flange_Design_Calculation.

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pritam
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#10
In reply to #6

Re: 32", 2500#Class Blind Flange Resulting Higher Hub Thickness

06/27/2011 3:20 AM

GA.
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skofitting
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#11
In reply to #6

Re: 32", 2500#Class Blind Flange Resulting Higher Hub Thickness

12/23/2011 1:59 AM

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Abdel Halim Galala (2); Anonymous Poster (1); Manpreet Singh (1); MJCronin (1); Mukesh0861 (1); pritam (2); skofitting (1); Tornado (2)

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