ASME B16.47 flange for high temperature

[JLu]

I’m designing a 36” manway on a SS 304H pressure vessel for 65 PSI/1400 F. When using the P/T ratings acc. ASME B16.47 for group 2.1 materials, I will need a 600# flange (400# would also be sufficient but is not common).
When selecting bolting material acc. Table 1B, it looks there are some discrepancies:

A) The GENERAL NOTE refers to the applicable design code for the max. allowable temperature for bolting. In my case, the code is ASME VIII div.1
B) The only bolting materials listed in table 1B of ASME B16.47 which may be used at 1400 F acc. ASME II are ‘Low strength’ bolts
C) According note 4 below table 1B in ASME B16.47, low strength bolting is not allowed above 300# flanges.

So, it seems there is no way to meet ASME B16.47 bolting requirements for a flange 600# at 1400F. (the same applies for ASME B16.5 flanges, although in my case I can stay with 300#)

Of course I can perform a ASME VIII div.1 appendix 2 calculation to solve this, but I guess it is not the intention of B16.5 / B16.47 to specify requirements which can never be fulfilled.

I’m looking forward to your opinions and/or experience with his.

Kind regards
JLU

 

[MJCronin]

1400F is not a reasonable design temperature for 304SS materials

 

[gr2vessels]

Did you consider using the SA 193 B8, B8C,M,T Cl.2 bolts? They are intermediate strength bolts per B 16.5/B16.47 and listed in Table D up to 1500F.
Cheers,
gr2vessels

 

[JLu]

Thank you guys for your replies.

@MJCronin: we use SS304H, not SS304. It may be used up to 1500F. (we are aware that the allowable stress is low and will result in a heavy, thick wall vessel)

@gr2vessels: You refer to Table D, do you mean ASME II part D?
As per ASME II, Class 1 bolting can be used up to 1500F but is low strength bolting and therefore not allowed for 600#. It seems Class 2 bolting can be used up to 800F or 1000F only.

Regards,
JLu

 

[DLite30]

You don't need high stength bolting for 65 psi(g). You just need bolts strong enough to allow for a tight joint and not exceed 80% tensile stregth.

 

[SnTMan]

JLu, looks to me like you are on your own. I agree with your assessment of B16.47 ( I am referring to an old, old copy).

The only steel bolting I see in Sec D, Part 2, Table 3 good for 1500 F and not classified as "Low Strength" in B16.47 is SA-193-8P.

You would have to justify it yourself as you stated in your OP.

DLiteE30, "You just need bolts strong enough to allow for a tight joint and not exceed 80% tensile stregth."

Agreed. At 1400 deg F. Choices are few.

Regards,

Mike

 

[DLite30]

ah, yes...I didn't read that post well enough.