CJP Weld with Backing Bar

[LSPSCAT]

I have a fabrication that requires CJP welds for moment connections in a grillage type frame. (Basically welding two wide flange shapes perpendicular to each other.) The intended use of the fabrication is underwater and we typically call to seal weld all joints to minimize corrosion. The CJP weld on the top flange is designed as a single bevel with backing bar. Can we fillet weld the backing bar in place to minimize corrosion or is this going to place a stress concentration at the backing bar? My other option is to remove the backing bar which will add considerable work to the job. Final option is to qualify welders with ceramic backing bar

 

[DVWE]

Can you change your joint design? I would consider changing the single bevel to a double bevel welded from both sides, if possible, and completely eliminate the backing bar.

 

[LSPSCAT]

Tight work conditions make weld access difficult, I think I have everyone on board with ceramic backing bar. Hopefully problem is solved. Thanks for your post.

 

[DVWE]

Ceramic backing bar is a viable option in your case.

Depending on the code of construction, seal welding a backing bar for corrosion resistance typically isn't restricted either.

 

[gtaw]

Only steel backing is considered to be prequalified. You will have to qualify the welding procedure with the ceramic backing if you elect to go that route.

Best regards - Al

 

[unclesyd]

Ceramic backing is used extensively in marine
constructions including vessels. I would check to see if
you need a specific procedure as the ceramic backing is not
part of the weld metal like a metal ring.
Also I think ABS has a pre qualification for welding with ceramic backing rings. Don't know if this is only for specific shapes.

I think someone like Cerbaco or Gullco would have this
information.

http://www.cerbaco.com/index.html

http://catalog.gullco.com/viewitems/ceramic-weld-backing/katbak-ceramic-weld-backing?&forward=1#