Bare Solid vs. Metal Cored 316L Filler for GTAW Welding 2

[beh188]

Is the use of metal cored filler permitted for pressure vessel construction? What does a metal cored filler get you as an advantage over a solid filler?

What exactly does flux do the welding process. Does it contaminate the weld and make it weaker?

 

[metengr]

You want bare solid wire for GTAW welding because shielding is provided by gas, not flux. Flux does two things - it protects the molten weld during deposition from harmful atmospheric gases and it can add necessary elements to the weld for chemical composition.

For flux core arc welding (FCAW) you have options using a metal core wire with flux. Gas shielding can be provided as a supplement. There is plenty of information on the internet regarding GTAW, FCAW, wires and flux.

 

[stanweld]

Metal cored wires for GTAW welding offer a greater ability to tailor weld metal chemistry at a lower cost and offer a slightly greater deposition rate. Additional welder training is recommended.

 

[muld0020]

You can use Flux Cored welding rod for GTAW per Section IX and used on Section VIII pressure vessels. It is an essetial variable when you do your WPS/PQR. We decided a few years ago to go this route for open root butt welds to eliminate the need for backing on the stainless welds. These consumables are not very readily available, but we had good success with it. The back side of the weld was as clean as it would be with a ceramic or Argon back purge. We don't always use it, since it has limitations.

One thing to note is that it practically only works for a single pass, then your subsequent passes should be with normal process (ie GTAW w/ solid or GMAW, SAW, FCAW). It also only works well for open root welds that have proper fit-up. I don't think it ties in well when you have backing. Also, clean up between passes , if I remember, may be less than perfect.