Stainless Steel Selection High Temp Environment
Stainless Steel Selection High Temp Environment
(OP)
I am looking for some assistance deciding the correct filler metal to use to weld non-code attachments in a high temp, high velocity location inside an HRSG. I have experienced weld cracking of 304 to 409 duct liner components and 304 to 304 & 310 to 310 header restraints. Max temp 1200 degrees in the inlet duct and up to 1500 degrees in front of the duct burner. Typicly a 309 filler would be used for the 304 to 409, 308 for 304 to 304 and 310 for the 310 to 310. I have wittnessed several weld failures in these locations with several different fabricators. Most failures are occuring within two years of service. Thinking maybe of going with a 304,310 with an L or H designation might be appropriate. I have read the addition of carbon will assist with temperature resistance to eliminate the cold cracking. Welds breaking off at the toe of the weld on the liner items and welds breaking in the center of the weld on the header restraints. Or maybe an Inconel or 347 filler would be the permanent fix?
Any help would be appreciated
Any help would be appreciated





RE: Stainless Steel Selection High Temp Environment
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RE: Stainless Steel Selection High Temp Environment
For the weld toe cracks in the duct liner, this could be low cycle (thermal) fatigue crack propagation. You might need to add additional bracing to strengthen (reduce flexing)the duct liners.
RE: Stainless Steel Selection High Temp Environment
The header restraints have been redesigned to allow better heat transfer. The higher ups believe they have the fix nailed down (as do I) but I am still concerned this issue and above are somehow related. I also am in favor of using inconel perhaps an erincr3? Would the same inconel filler be acceptable for joining both 304 to 304 (inlet duct restraints) as well as the 310 to 310 upstream of the duct burner? Would you suggest a gtaw or a smaw process?
Sorry for the long post and all the questions. Your thoughts appreciated.
RE: Stainless Steel Selection High Temp Environment
This is a very important observation, and implies that what is being done in the field is not the same approach that is done in the shop. You need to research this item and determine what changes are being done in the field versus the shop.
This is another important observation. If what you are reporting is correct, this could be a dissimilar metal weld failure or poor welding technique. Normally, the dissimilar metal weld failure would occur on a ferritic to austenitic stainless steel joint because of carbon migration (ferritic side). Switch from 309 to Inconel (ERNiCr-3).
Go with the GTAW process. For the 304 to 304, I would consider ER308H and for the 310 to 310, I would use ER310.
RE: Stainless Steel Selection High Temp Environment
The ferrite in stainless weld metals will turn to sigma in over the 1200-1500F temperature range you mentioned. On occasion flux cored wire can have very high ferrite, or at least not be what you think it is. I would suggest making all of these dissimilar metal welds using alloy 82 (ERNiCr-3) wire or 182 (ENiCrFe-3) covered electrodes.
If you wish illustrations of appropriate weld joints, email me jkellymetal@gmail.com
James Kelly
James Kelly
www.rolledalloys.com
RE: Stainless Steel Selection High Temp Environment
Will I see you in Nashville?
Ed B.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm