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Hi,
A simple answer is ask your welding engineer (this is basic welding knowledge). The code is silence about your question. You know the forewords of ASME VIII/1 and ASME IX? In both sections you will find the following sentence:
“ …..The Code is not a handbook and cannot replace education, experience, and the use of engineering judgment. …”.
Therefore, believe me, a vessel manufactured only acc. to ASME BPVC will be a vessel with poor quality.
However, here is the answer.
You question is not precise enough. You have unfortunately not mentioned:
-the process(es)
-the thickness of the joint
-is PWHT performed
-the operation temperature.
In any case, the use of overalloyed filler metal for joint of dissimilar base metals is essential.
But there are to possibilities:
1) no PWHT is performed and the service temperature is max. 300 °C
2) PWHT is performed or the service temperature is > 300 °C
For the first bullet point the use of overalloyed austenitic filler metal, e.g. E307-15 is ok. But if the joint is thicker the groove face of the carbon steel have to be buttered with this electrode and for the joint of the buttered groove face to the austenitic steel use the electrode for the austenite.
For the second bullet point the use of Ni-base filler metal, e.g. ENiCrFe-3 is necessary. In addition, if PWHT is performed the resistance to intercrystalline corrosion of the austenitic base metal has to be considered. That means the following manufacturing sequence must perform:
-buttering of groove face of the carbon steel with Ni-base alloy electrode above
-Local PWHT of the buttered groove face as required for SA-516 Gr. 70
-welding of SA 312 TP 304L to the buttered groove face of the carbon steel with the Ni-base alloy electrode above.
Hope that helps
_________________
Kind regards,
Juergen Fleischfresser
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