MAWP CACULATION FOR TOP FLAT HEAD 16"+ x 600# BLIND FLANGE

[hplogger]

Can anybody provide me the MAWP formula/calculation of a top flat head (blind flange material, 16"Ø x 600#). Please help! Moreover, please provide me as well the material density of SA 105N material. Thank you in advance!

 

[Shmulik]

You are holding a Standard Flange, thus, you should have the MAWP from ASME B16.5 Tab. 2-1.1 acc. to the max. design temp.
You may calculate your flange acc. to VIII-1 App. 2, But results are not always comply with B16.5 Pressure-Temperature Ratings.

 

[hplogger]

Thank you, Sir. However, i wanted to determine the MAWP with the following conditions:
a.) Hot & Corroded (at the top of completed vessel in its operating position)
b.)Cold & New (at the top of completed vessel in its operating position)
c.)Cold & Corroded (at the top of the completed vessel in its operating position)

Please help! Thank you in advance.

 

[Shmulik]

hplogger,

1. Code permits using of standard flanges acc. to press.-temp. ratings specified in the appropriate standard: UG-11(a)(2) + UG-44.
2. Be aware of MDMT requirements for selecting flange material.
3. Pressure to be considered for your flange is design press. / MAWP at top of the vessel + static head over flange location. Be aware of the possibility that operating media density is lower than testing media. If so, you should consider testing media static head.
4. Dimensions of flange (your flange is ASME B16.5 Tab. 18) are not applicable to corroded conditions (Interpretation 2-27 to ASME B16.5 1996: "The applicability of press.-temp. ratings for material that is corroded or otherwise deteriorated is the responsibility of the user").
5. For corroded conditions you may rerate your flange acc. to the rules of app. 2 for the ring flange + UG-34 (sketch j or k) for the blind. Please note that the blind flange does not stay alone, as you should consider gasket material, contact facing and bolting.

I suggest you look at former discussion on this topic: thread292-179367

 

[doct9960]

hplogger,

Are you trying to determine the MAWP/MAP of the vessel (including blind) or just the blind flange?

Are there nozzles on the blind flange?

 

[hplogger]

Dear doct9960,

Just the MAWP of the blind flange considering the conditions above. The blind flange is attached to a weld neck flange, 16"Ø x 600#, RF which is welded to shell(pipe 16"Ø, Sch. 80).

 

[doct9960]

hplogger,

If your blind flange is a standard B16.5 blind, your MAWP/MAP should be derived from Table 2-1.1 (or Table F2-1.1) of ASME B16.5.

MAWP (hot & corroded) = MAWP @ design temperature
MAP (new & cold) = MAP @ test water temperature
MAP (new & corroded) = MAP (new & cold)

Note that the pressure-temperature ratings in B16.5 does not include corrosion allowance.

What are the design pressure, design temperature, and hydrotest water temperature of your vessel? I could probably tell you the MAWP/MAP of your blind. (if it's a standard B16.5 blind)

 

[hplogger]

doct9960,

design pressure = 700.11 psi
design temperature = 599 deg. F
hydrotest min. temperature = 52 deg. Celsius

 

[doct9960]

hplogger,

Your hydrotest water temperature seems too hot. I will assume 52 deg Fahrenheit. So the following are the MAWP/MAP of your blind...

MAWP (hot & corroded) = 1135.7 psi
MAP (cold & new) = 1480 psi
MAP (cold & corroded) = 1480 psi

 

[hplogger]

Absolutely, Sir. Thank you for the help.