Composite Material for Vessels

[PEHasan]

Can we build a pressure vessel from SA240 TP 316L material with Duplex SS (UNS S31803) nozzles? If yes, what important things do we have to take into consideration while carrying out the design calculations? Also what electrode we can use for the welding of this composite vessel. Is there anything important that we have to consider for the fabrication of this vessel?

Regards,

PEHasan

 

[gr2vessels]

PEHasan,

Yes, you can design the austenitic vessel fitted with Duplex nozzle, as the welding is not a difficult operation (assuming a proper welding procedure). The nozzle reinforcement calculations however, cannot take in account the higher allowable design stresses for the Duplex material.
The low heat input during welding is critical ( less than 1 J/mm) for hardness control and carbide precipitation control, since the PWHT is not recommended.

gr2vessel

 

[SnTMan]

I would add that your duplex will probably need to be impact tested, perhaps the weld as well.

Regards,

Mike

 

[EdStainless]

I would impact test the welds since they will be somewhat duplex in structure.
As for filler, what does the mill making the duplex recommend? You could go either way, austenitic or duplex filler.

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[gr2vessels]

SnTMan and EdStainless

Please include in your advice to PEHasan, any reference which recommends impact test on the Duplex stainless steel material or its welding / HAZ.

Cheers,

gr2vessel

 

[SnTMan]

PEHasan, gr2vessels, my assumption is that this is a Sec VIII, Div 1 application. If so, requirements that duplex steels be impact tested is found in UHA-51, 1st paragraph. Basis for exemption is found in UHA-51(d)(3)(a).

Requirements for impact testing weld and HAZ are fairly involved and depend on the filler metal used, but are found in UHA-51 (b). Requirements for production testing are found in UHA-51 (f).

Hope this is useful,

Mike

 

[MJCronin]

hasan....

I am curious....

Is this a new vessel ? If so, why do you want just the nozzles to be constructed from a duplex material ?

I cannot imagine a process chemical service that would require this unique configuration...

-MJC