Welding and bending 321 stainless steel 1

[don867]

I need to make a 8" diameter coil out of .20 wall 1/2" diameter 321 tubing .Could you tell me what size and kind of rods to weld with ?I was planing to stuff the tubing with sand,then rape it around a mandrall wile applying heat to it. how do you think it will work?

 

[metengr]

The tube butt welding can be done using the GTAW process with ER347 filler metal. What is the service application of this coil? I would not hot bend because it can effect the performance of the 321 in service. This tube can be cold bent using the proper dies.

 

[Goahead]

metengr

Do you mean that you would not "heat"?

http://www.welding-advisers.com/

 

[metengr]

Goahead;
Correct. This material has sufficient ductility for cold bending. The question is what the intended service of the coil.

 

[don867]

The coil is in a gluhareff 130r pressure jet engine.There are two coils in the burn chamber.liquid butane runs through the coils and is heated then run back out of the chamber and is injected in to a intake manifold where it is mixed with air ,then the mixture is roughted in to the burn chamber were it burns.the temper is about 3000 fahrenheit in the burn chanber.The liquid butane is at about 140psi.when it goes in the coils

I was told by mr. Gluhareff(he pasted way in 1994) a long time ago to make the coil you had to aneal the tubbing ,fill it with sand an then rape it around a mandrall.

The engine was built in 1988 and has lasted a long time.
the coils have cracks .I have the 321ss tubing to make two new one ,any advice would be a big help.

 

[metengr]

don867;
Yes, the tubing is cold bent with sand to avoid crimping. The annealing is done beforehand to assure that the material is at its lowest strength for forming.

My recommendation is to have the coil re-annealed after cold bending to assure maximum corrosion resistance and elevated temperature properties.

 

[EdStainless]

My guess is that with the service temp involved re-annealing is not needed. I would only change my stand if you will be welding on the coil (and the welds will be in the hot section), then I might suggest post-fabrication annealing.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[metengr]

Sorry Ed, but I have to disagree. In working with 321 ss, cold working this material will reduce elevated temperature mechanical properties. This is part of the reason why we established formability limits in ASME Section I, PG-19.

If you cold work in excess of 15% strain AND have exposure to service temperatures between 1000-1250 deg F, or exposure to service temperatures above 1250 deg F AND 10% strain we had instituted requirements for a post fabrication anneal. I would follow these requirements if the coil is eposed to service temperatures above 1000 deg F.