ASME B31.3 - Aluminium Flanges
ASME B31.3 - Aluminium Flanges
(OP)
Hi all,
Very quick question regarding Appendix L of B31.3. Does anyone know the reason why the pressure-temperature ratings for socket welding flanges are lower than that of welding neck?
I've looked at the EN equivalents for the aluminium flanges and well, EN 1092-4 has only WN (Type 11) / blinds (Type 05) and EN 1759-4 is the same, so that doesn't help...
Very quick question regarding Appendix L of B31.3. Does anyone know the reason why the pressure-temperature ratings for socket welding flanges are lower than that of welding neck?
I've looked at the EN equivalents for the aluminium flanges and well, EN 1092-4 has only WN (Type 11) / blinds (Type 05) and EN 1759-4 is the same, so that doesn't help...





RE: ASME B31.3 - Aluminium Flanges
By yhe way, Ive never seen an application using aluminum flanges under B31.3. What could be it's potential use or application?
RE: ASME B31.3 - Aluminium Flanges
The actual use would be on a pressure vessel nozzle (ASME VIII, Div 1), however the P/t ratings from B16.5 do not exist for 6061 and when using the same dimensions as those from B16.5 for the flanges, say class 300, the ratings are then taken from B31.3 appendix L. Then the issue would be that the ratings from appendix L are a bit more aggressive when comparing to calculated flange ratings using Div 1 or even div 2...
RE: ASME B31.3 - Aluminium Flanges
What would be more in line with VIII-1 Code requirements is to select an aluminum alloy from section II part D, and use that material as a basis for a flange calculation acc. VIII-1 appendix 2.
Why not use 304/304L material for cryo? Isnt that much simpler? Or does aluminum provide an advantage over 304/304L?
RE: ASME B31.3 - Aluminium Flanges
The aluminium flanges are used a lot on the nozzles for heat exchangers. You can go for a lap joint flange with ally stub / 304/L flange, or if we wanted to be fancy, a transition joint for 6061/304. Typically though, it is just a RFWN in aluminium with a stainless mate.
RE: ASME B31.3 - Aluminium Flanges
Why not use aluminum B16.11 lap joint stub ends with B16.5 304 lap joint flanges? Your rating than also isnt limited.
On a side note; you can easily buy Ti flanges (from fraudulent factories), which are sold and marked as 'B16.5' standard. That doesnt mean they meet B16.5 requirements and are listed as such.