Pressure rating for ANSI flanges and Pipe
Pressure rating for ANSI flanges and Pipe
(OP)
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,
Thanks,





RE: Pressure rating for ANSI flanges and Pipe
RE: Pressure rating for ANSI flanges and Pipe
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.
RE: Pressure rating for ANSI flanges and Pipe
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" - 24" and temperatures -425F to 1500F. I checked out their website but all they show is product information.
Hope this helps
RE: Pressure rating for ANSI flanges and Pipe
Thanks again,
Reb
RE: Pressure rating for ANSI flanges and Pipe
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
RE: Pressure rating for ANSI flanges and Pipe
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.
RE: Pressure rating for ANSI flanges and Pipe
Best Regards,
Kirk
RE: Pressure rating for ANSI flanges and Pipe
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" NPS. Larger than 24" 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.
RE: Pressure rating for ANSI flanges and Pipe
RE: Pressure rating for ANSI flanges and Pipe
Further to mtk220's note concerning B31.3 factors, remember that the "minus" manf. mill tolerance changes to either 8 or 10 percent for 20" 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).