I have this job in my in hand project. I know your problem exactly:1- if you don't increase the overlay thickness you will not find the chemical composition in PMI test because you need minimum 6mm thickness for get the composition (3mm overlay with 309 and 3mm overlay with 316 filler) 2- if you...
we are using the filler EH12K for this type of welding.(thichness 25~60mm with PWHT). you can find our WPS and welding process specification in attached.
i hope this document can help you. http://files.engineering.com/getfile.aspx?folder=7e85925c-4ad7-49b1-8821-016ff7145a57&file=WPS.pdf