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qaqcpipeman
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Join Date: Sep 2006
Location: Western Pennsylvania, USA
Posts: 761
Good Answers: 9

Thickness and Pressure Rating of Blind Flanges

10/30/2008 7:45 PM

Below are 2 threads from another forum I suscribe to.

Can anyone help my associate and cite the Appropriate Standard?

I am in the field sans good access to info just right now.

does anyone have a down and dirty chart for slip blind
thickness for hydros. Need to compare diameters and pressure. any help would be appreciated.

I'm still up in "Middle of nowhere" Wyoming. What i am really
looking for is thicknesses for temporary blanks/blinds for hydro's.
These guys are trying to use 1/8" thick blinds on 14" by 800psi line.
I know its not right, i just cant find the documentation to back it up.
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chama2633
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Location: Muscat, Sultanate of Oman
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#1

Re: Thickness and Pressure Rating of Blind Flanges

10/31/2008 11:15 PM

See MSS SP44 Annex C

This spec states - blind flanges in no case shall be thinner than the corresponding welding neck flange.

What is the fishing like?

Chama
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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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#2

Re: Thickness and Pressure Rating of Blind Flanges

11/01/2008 6:42 AM

A. We have to define the flange rating/class : 150#, 300#, 400#, 600#, 900#, 1500# & 2500# (see ASME B16.5). And to find the rating/class of flange, we have to know: 1. the flange material, 2. design pressure and 3. design temp. regardless of its NPS. For example:

Flange Material : Carbon steel ASTM A105

Design Pressure: 800 psi (differ from operating pressure)

Design Temp.: 100oF (Ambient)

For material ASME SA105 in Table F2-1.1 of ASME B16.5, the flange rating 400# will withstand a design pressure of 985 psi ≥ 800 psi. So the flange rating shall be 400#, regardless of its NPS.

B. From ASME B16.5, Table F14-400#, for flange 14" NPS, the min.thickness of flange tf is 2.38", and this thickness remains the same for all types of flanges of that size and rating (Blind, WN, SO, SW, NPT & Lapped).

Please see ASME B16.5 Flanges to calculate the max. design pressure of flange, and see the following CR4 Threads: Pound Rating, Pressure Rating, PN numbers vs. valve class in ASME standard.

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flynnstar
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Join Date: Feb 2008
Posts: 77
Good Answers: 5
#3

Re: Thickness and Pressure Rating of Blind Flanges

11/01/2008 10:19 AM

Go to Taylor Forge Web site

www.tfes.com

You will get an "intro" page. Go to RESOURCES, STD. FLANGE & FITTING DIM, INCH.

You will get a free signup page to the site. Fill this out and a new page will appear in which you can click again on Inches. This will give you a complete array of data including blind flange thickness for ANSI pressure class up to 1500.

1/8 inch "is a little light". As I recall, a 14" Class 400 blind flange is something like 2-3/8" thick!
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Anonymous Poster
#4

Re: Thickness and Pressure Rating of Blind Flanges

11/01/2008 1:03 PM

also dont forget to use the proper bolts or studs for the application. I would use b7 studs and gr 2 xh nuts.
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Anonymous Poster
#7
In reply to #4

Re: Thickness and Pressure Rating of Blind Flanges

04/20/2010 4:47 PM

how can i calculat the thikness of blind flanges
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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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Location: Cairo, Egypt
Posts: 1733
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#8
In reply to #7

Re: Thickness and Pressure Rating of Blind Flanges

04/21/2010 11:54 PM

Free download this file: Blind_Flange_Design_Calculation.

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qaqcpipeman
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#5

Re: Thickness and Pressure Rating of Blind Flanges

11/03/2008 7:48 AM

Thanks to everyone for your posts.

I am sure my associate is headed in the right direction now, with the right ammo for the debate with the field crew
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Anonymous Poster
#6

Re: Thickness and Pressure Rating of Blind Flanges

05/15/2009 6:39 PM

Don't the slip and spectical blinds fall under ANSI 31.3 not the pressure vessel code? If the blinds were temporary for hydro at ambinent temperature, and not for isolation under service conditions, the slip blinds could be much thinner, depending on the material. eg hi strength Vs low strength.
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Anonymous Poster
#9

Re: Thickness and Pressure Rating of Blind Flanges

10/25/2010 10:17 AM

It should be at least 1 1/8" that is one inch and an eigth of an inch thick, I just found out on your question I hope is not too late, be safe.
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Abdel Halim Galala (2); Anonymous Poster (4); chama2633 (1); flynnstar (1); qaqcpipeman (1)

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