ElCidCampeador
Mechanical
- May 14, 2015
- 274
Hi,
a friend of mine, who works in a workshop, is asking me if he can do something for this issue.
He is building a pressure vessel acc.to EN 13445, Gr.1.2 (c.steel).
This vessel has a shell with a nozzle bended from plate; this nozzle is welded to the vessel with a set-in weld and has a reinforced pad. At the end of the nozzle it is welded a WN flange with butt weld.
My friend told me that he forgot to PFHT the nozzle (since nozzle is cold formed by bending and F>5%), but now all welds has been done and the nozzle is already welded to shell and to welding neck flange.
He suggests, in order to "save" the situation, to PFHT locally "only" the nozzle (not pad or WN flange, just the rolled part), taking care to stay at an appropriate distance from welds in order to not create thermal stress.
I told him that the correct procedure would be cutting all welds and PFHT the nozzle separately (with test coupon) and then re-weld.
I don't know what he will do, but if the final purpose is to "save" material in the best way as possible (without cutting anything), do you really think that it's better PFHT the portion of nozzle bended (without welds) than leaving the nozzle as welded now (so with deformation due to bending)? My fear is that new local heat treatment would add more stress, expecially close to welds, instead of "reset" material behaviour...what do you think is the least worst solution?
Thanks
a friend of mine, who works in a workshop, is asking me if he can do something for this issue.
He is building a pressure vessel acc.to EN 13445, Gr.1.2 (c.steel).
This vessel has a shell with a nozzle bended from plate; this nozzle is welded to the vessel with a set-in weld and has a reinforced pad. At the end of the nozzle it is welded a WN flange with butt weld.
My friend told me that he forgot to PFHT the nozzle (since nozzle is cold formed by bending and F>5%), but now all welds has been done and the nozzle is already welded to shell and to welding neck flange.
He suggests, in order to "save" the situation, to PFHT locally "only" the nozzle (not pad or WN flange, just the rolled part), taking care to stay at an appropriate distance from welds in order to not create thermal stress.
I told him that the correct procedure would be cutting all welds and PFHT the nozzle separately (with test coupon) and then re-weld.
I don't know what he will do, but if the final purpose is to "save" material in the best way as possible (without cutting anything), do you really think that it's better PFHT the portion of nozzle bended (without welds) than leaving the nozzle as welded now (so with deformation due to bending)? My fear is that new local heat treatment would add more stress, expecially close to welds, instead of "reset" material behaviour...what do you think is the least worst solution?
Thanks