Bolt MAWP

[krishsar]

Hi All,

Can anyone please tell me how to find the bolt MAWP. Normally Compress & PV Elite does not calculate it but ASPEN BJac does it.

I whant to know what is formula used to calulate the MAWP of Bolting??

Regards,
KR

 

[XL83NL]

There is no MAWP for a bolt as it does not directly contain pressure. When used in e.g. flanges, it contributes to the pressure envelope, but even then there's no way of providing an MAWP for a bolt. Looking at say a 1 " B7 bolt in a 10" vessel with a (vessel-)MAWP of 100 bar(g), that same bolt may, when used in a 20" vessel, be limited to e.g. 50 bar(G) MAWP.

 

[SnTMan]

krishsar, for an Appendix 2 flange it appears you could solve the expression Ab * Sb = H + Hp for pressure, P, keeping the other quantities constant. Giving the maximum pressure load for the available bolt area, at design bolt stress.

Given the difference between design and service bolt stresses this may not be a particularly useful calculation, but it could be done.

Regards,

Mike

 

[krishsar]

Hi XL83NL,

Please see attached flange cal. & MAWP summary. where you can find the bolting MAWP. The program used in ASPEN B-Jac

If possible please explain how the program calculates it.

Regards,
KR

 

[krishsar]

SnTMan,

Sorry i could understand your reply. Could you please give it as a formula for better understanding. And also refer to my previous reply to XL83NL.

Regards,
KR

 

[TomBarsh]

COMPRESS will indicate in the report if the MAWP of the Appendix 2 flange is limited by (controlled by, governed by) the bolts. I suggest you review the rules of Appendix 2 that relate the bolt stresses and flange analysis.

Tom Barsh - Codeware
speaking for myself only, not an official Codeware opinion

 

[XL83NL]

Again, a flange may have a MAWP. When the program reports a flange's MAWP, it may associate the bolt's MAWP with that flange (in fact I dont know, as I dont know ASPEN BJac, but thats what I think). Have you read the manual, and contacted Aspen on this topic?
A bolt does however have a max allowable stress, and stress may be expressed in the same unit as MAWP (e.g. MPa), even though theyre 2 different things. I suggest you do some reading of ASME VIII-1 app 2 first.

 

[SnTMan]

krishsar, it is all there in your output. Ab * Sb = H + Hp

Regards,

Mike

 

[krishsar]

Thanks SnTMan for your reply. Still i did not arrive the MAWP for Bolt.

Anyway i will read App-2 again as XL83NL & TomBarsh said.

Regards,

Mike

 

[chicopee]

As state above, MAWP does not apply to bolts, the initials MAWP only apply to pressure vessels ( fired or unfired).

 

[prex]

The MAWP calculated by Aspen is obtained from:
23.06(MAWP for bolting)=12.8(DP)*138949(WM2:bolt load determining AM)/83625(WM1:bolt load due to pressure)*8572.9(AB)/7905.3(AM)
This gives the pressure which generates the allowable operating stress in the bolting (consistently with MAWP definition).
Can't imagine a real world situation where this value would be dominant, but in this case the MAWP for the vessel would be determined by bolting.

prex
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[krishsar]

Thanks Prex, Even though it does not exist in real world my client requires it.

Thanks again Prex.

Regards,
KR