Welding problems of P11 and TP347H dissimilar steels
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Recently, we encountered a problem: the reaction heating furnace in a newly built high-pressure hydrogenation unit uses TP347H furnace tubes, while the pipeline from the outlet of the heating furnace to the reactor is made of P11. There are several welding processes available for welding austenitic stainless steels and pearlitic stainless steels. We recommend using a transition layer for surfacing on P11, followed by heat treatment; after the groove is mechanically processed and found to be satisfactory, it can then be welded to TP347H ； Some suggest using nickel-based electrodes for direct welding. Given that the system pressure is 19 MPa, the temperature is around 400 degrees, and the medium inside is hydrogen, the operating conditions are quite harsh. Using flange connections is also very dangerous. I would appreciate any suggestions you might have; thank you!
One more thing: the key to this issue is whether everyone has practical experience to draw on in their work
In ethylene plants, there are often examples of welding stainless steel pipes of types P11 and 304H, using ERNiCrMo-3/ENiCrMo-3 nickel-based welding materials, without the need for heat treatment. For welding between P11 and 347H stainless steels, it is considered feasible to use the same welding process, which can be certified through process qualification.