Pressure rating for ANSI flanges and Pipe 1

[rebel]

I am trying to establish some guidelines to hydrostatic test pipe spools. Does anyone know where I can locate the design or working pressures for Pipe and Flanges?

Thanks,

 

[TBP]

I have to say this - please don't be offended, because I know you've come here for help. In addition to this question, you've got another posted asking what the difference between "PSIA" and "PSIG" is. You haven't got the fundamental building blocks of information to proceed with trying to establish guidelines for the hydrostatic testing of pipe spools. Please don't start or carry on with this project alone. Find someone with a background in pressure piping and ASME codes to help you. This is not an area you'll be able to effectively deal with by reading a few postings on a a bulletin board, or thumbing through a textbook. Really.

 

[rebel]

Thanks and I understand what your saying but I have already calculated the allowable working pressures for pipe sizes 1” through 8”, schedule 10, 20, 40, and 80. My equation looks like this:

P = S (D^2 - d^2) / (D^2 + d^2) for D/t < 10 & P = 2 S t / D for D/t > 10

Where P is my pressure, S = allowable stress value for a particular material of pipe, and
D = Outside Diameter.

Thanks for your concern.

 

[tr6]

Allowable pressure ratings are determined by the formula given in ANSI B31.1 & B31.3 as follows:

P= 2*S*T/D

Where:
T = design thickness of the pipe (12-1/2% less than the nominal wall thickness of any given pipe size to account for manufacturing tolerances)- inches
P = Internal design pressure. PSIG
D = Outside pipe diameter of the pipe - inches
S = Allowable stress for the materials at service temperature
E = Joint Efficiency of the pipe:
1.0 for seamless pipe
0.85 for welded pipe

Actually, a lot of pipe manufacturers have already done what you are doing and have included it in their product catalogs. I have an old catalog, because I'm old, from FLOWLINE, which covers the stainless alloys -304, 316, A 400, A200, and aluminum for all sizes 1/2&quot; - 24&quot; and temperatures -425F to 1500F. I checked out their website but all they show is product information.

Hope this helps

 

[rebel]

Thank you very much &quot;tr6&quot; for your useful thread. I think I have it figured out.

Thanks again,

Reb

 

[mgp]

Someone must have DESIGNED this spool (i.e apart from geometry, finding out thickness of pipe, rating of flange etc) before it can be fabricated and tested.

In order to design a spool someone has to know the design pressure and which design code to use for the design.

Once you know these you normally also get to know the test pressure.

You should really ask those who did the design.

regards
Mogens

 

[DSB123]

tr6,
Please note that the Codes you refer to are ASME B31.3 and ASME B31.1 These are the latest Codes and are now ASME and not ANSI standards. Also if we are talking about Flange ratings then the Standard is also ASME B16.5 not ANSI.

 

[kklinger]

There is information about ANSI flanges including pressure ratings at

http://www.thermometricscorp.com.

The pressure rating of these flanges is depedent on the material type and temperature. Hope this helps you.

Best Regards,

Kirk

 

[mtk220]

Rebel,
TBP, the first to answer, gave you the best advice. People are throwing formulas at you that are not based on reality. You should use the formula in ASME B31.1 for Power Piping and/or B31.3 for Chemical Plant and Refinery Piping. Each describes the hydrotest requirements as well. BUT, there are other factors that add in. For example, no one even mentioned that you have to consider the manufacturer's allowance on pipe thickness which is 12-1/2%. Then as mentioned it is required to consider joint factors for welded pipe as well.
ASME B16.5 will give you current pressure ratings for each class of flange for each material group up to 24&quot; NPS. Larger than 24&quot; use ASME B16.47.
If you don't have these publications find someone who does and someone who knows how to apply them.
Best of luck.

 

[DavidCR]

The flanges code ASME B31.5 indicates the ratings but also includes information on what hidrostatic test pressures can be used (parr.2.5). So you have to see on the design code (B31.1 or B31.3 for example), the accesory code (B31.5) or other code that may apply to the system.

 

[facilityengr]

DavidCR is correct on this matter.
Further to mtk220's note concerning B31.3 factors, remember that the &quot;minus&quot; manf. mill tolerance changes to either 8 or 10 percent for 20&quot; and greater. Please also remember the weld joint quality factor, E, is not simply 0.85 for welded pipe and 1.0 for seamless, it depends on the type of weld. SAW API 5L is 0.95 for example (Table 302.3.4).