Detailed fabricating information for C-22 alloy is available in the booklet, Fabrication of HASTELLOY® Corrosion-Resistant Alloys (H-2010) and C-22® Alloy Welding Information (H-2066). http://www.haynesintl.com/pdf/h2010.pdf
The ERNiCrMo-10, which is the matching filler for C22 to C22, can also be used to weld C22 to 316L. There are other nickel alloy filler that would be alternates, such as ERNiCrMo-4. The 300 series stainless fillers would not be recommended.